Air Timeline

2008-03-18T11:12:00.001-07:00

The Cloudspotter's Guide

2008-03-18T11:06:00.000-07:00

A unique and far-ranging romp through science, history, art, and pop culture -- written for anyone who’s curious about those fluffy, floating, ever-shifting cotton balls in the sky...

Where do clouds come from? Why do they look the way they do? And why have they captured the imagination of timeless artists, romantic poets, and every kid who’s ever held a Crayon? Veteran journalist and lifelong sky-watcher Gavin Pretor-Pinney reveals everything there is to know about clouds, from history and science to art and pop culture. Cumulus, nimbostratus, and the dramatic and surfable Morning Glory cloud are just a few of the varieties explored in this smart, witty, and eclectic tour through the skies.

Generously illustrated with striking photographs and line drawings featuring everything from classical paintings to lava lamps, children’s drawings, and popular advertisements, The Cloudspotter’s Guide will have enthusiasts, poets, weather watchers, and the just plain curious floating on cloud nine. Looking up will never be the same again.

Liquid breathing

2008-03-18T10:54:00.000-07:00

Liquid breathing is a form of respiration in which a normally air-breathing organism breathes an oxygen-rich liquid (usually a perfluorocarbon), rather than breathing air. It is used for medical treatment and could some day find use in deep diving and space travel. Liquid breathing is sometimes called fluid breathing, but this can be confusing because both liquids and gases can be called fluids.

Methods of application

Despite recent advances in liquid ventilation, a standard mode of application of perfluorocarbon (PFC) has not been established yet.

Total liquid ventilation

Although total liquid ventilation (TLV) with completely liquid filled lungs is beneficial, the necessity for the liquid filled tube system that contains pumps and heater and membrane oxygenator to deliver and remove tidal volume aliquots of conditioned perfluorocarbon to the lungs is a disadvantage with regard to gas ventilation. One research group led by Thomas H. Shaffer has maintained that with the use of microprocessors and new technology, it is possible to maintain better control of respiratory variables such as liquid functional residual capacity and tidal volume during TLV, than with gas ventilation. ^[1]^[2]^[3]^[4].

[edit] Partial liquid ventilation

In contrast, partial liquid ventilation (PLV) is a technique in which a PFC is instilled into the lung to a volume approximating functional residual capacity (approximately 40% of TLC (Total Lung Capacity)). Conventional mechanical ventilation delivers tidal volume breaths on top of this. This mode of liquid ventilation is technically more viable than total liquid ventilation as it can utilise technology currently in place in neonatal intensive care units (NICU) worldwide.

The influence of PLV on oxygenation, carbon dioxide removal and lung mechanics has been investigated in several animal studies using different models of lung injury^[5] Clinical applications of PLV have been reported in patients with Acute Respiratory Distress Syndrome (ARDS), meconium aspiration syndrome, congenital diaphragmatic hernia and Respiratory Distress Syndrome (RDS) of neonates. In order to correctly and effectively conduct PLV, it is essential to (1) properly dose a patient to a specific lung volume (10-15 ml/kg)to recruit alveolar volume and (2) redose the lung with PFC liquid (1-2 ml/kg/hr) to oppose PFC evaporation from the lung. If PFC liquid is not maitained in the lung, PLV can not effectively protect the lung from biophysical forces associated with the gas ventilator.

New application modes for PFC have been developed^[6].

[edit] PFC vapor

Vaporization of perfluorohexane with two anesthetic vaporizers calibrated for perfluorohexane has been shown to improve gas exchange in oleic acid induced lung injury in sheep ^[7]. Predominantly PFCs with high vapor pressure are suitable for vaporization.

Aerosol-PFC

With aerosolized perfluorooctane, significant improvement of oxygenation and pulmonary mechanics was shown in adult sheep with oleic acid-induced lung injury. In surfactant-depleted piglets, persistent improvement of gas exchange and lung mechanics was demonstrated with Aerosol-PFC ^[8]. The aerosol device is of decisive importance for the efficacy of PFC aerosolization, as aerosolization of PF5080 (a less purified FC77) has been shown to be ineffective using a different aerosol device in surfactant-depleted rabbits (Kelly). Partial liquid ventilation and Aerosol-PFC reduced pulmonary inflammatory response ^[9].

Summary of clinical uses

At present all modes of liquid ventilation remain experimental. PLV has been used in only a small number of patients worldwide. The technique is currently only employed in specialist centers usually as part of a randomized controlled trial. With the accumulation of evidence supporting the safety and efficacy of liquid ventilation it is probable that it will become an important technology for the future treatment of patients in respiratory distress.

Potential uses

Diving

In diving, the pressure inside the lungs must effectively equal the pressure outside the body, otherwise the lungs collapse. Mathematically speaking, if the diver is f feet (or m meters) deep, and the air pressure at the water surface is p bar (usually p = 1, but less at high-altitude lakes such as Lake Titicaca), he must breathe fluid at a pressure of f/33+p = m/10+p bar.

Since external and internal pressures must be equal, the required gas pressure increases with depth to match the increased external water pressure, rising to around 13 bar at 400 feet (120m), and around 500 bar on the oceans' abyssal plains. These high pressures may have adverse effects on the body, especially when quickly released (as in a too-rapid return to the surface), including air emboli and decompression sickness (colloquially known as "the bends"). (Diving mammals, as well as free-diving humans who dive to great depths on a single breath, have little or no problem with decompression sickness despite their rapid return to the surface, since a single breath of gas does not contain enough total nitrogen to cause tissue bubbles on decompression. In very deep-diving mammals and deep free-diving humans, the lungs almost completely collapse).

One solution is a rigid articulated diving suit, but these are bulky and clumsy. A more moderate option to deal with narcosis is to breathe heliox or trimix, in which some or all of the nitrogen is replaced by helium. However, this option does not deal with the problem of bubbles and decompression sickness, because helium dissolves in tissues and causes bubbles when pressures are released, just like nitrogen does.

Liquid breathing provides a third option. With liquid in the lungs, the pressure within the diver's lungs could accommodate changes in the pressure of the surrounding water without the huge gas partial pressure exposures required when the lungs are filled with gas. Liquid breathing would not result in the saturation of body tissues with high pressure nitrogen or helium that occurs with the use of non-liquids, thus would reduce or remove the need for slow decompression. (This technology was dramatized in James Cameron's 1989 film The Abyss.)

A significant problem, however, arises from the high viscosity of the liquid and the corresponding reduction in its ability to remove CO₂. All uses of liquid breathing for diving must involve total liquid ventilation (see above). Total liquid ventilation, however, has difficulty moving enough liquid to carry away CO₂, because no matter how great the total pressure is, the amount of partial CO₂ gas pressure available to dissolve CO₂ into the breathing liquid can never be much more than the pressure at which CO₂ exists in the blood (about 40 mm of mercury (Torr)).

At these pressures, most fluorocarbon liquids require about 70 mL/kg minute-ventilation volumes of liquid (about 5 L/min for a 70 kg adult) to remove enough CO₂ for normal resting metabolism.^[10] This is a great deal of fluid to move, particularly as liquids are generally more viscous than gases, (for example water is about 56 times the viscosity of air). Any increase in the diver's metabolic activity also increases CO₂ production and the breathing rate, which is already at the limits of realistic flow rates in liquid breathing.^[11]^[12] It seems unlikely that a person would move 10 liters/min of fluorocarbon liquid without assistance from a mechanical ventilator, so "free breathing" may be unlikely.

Medical treatment

The first medical use of liquid breathing was treatment of premature babies and adults with acute respiratory distress syndrome (ARDS) in the 1990s. Liquid breathing was used in clinical trials after the development by Alliance Pharmaceuticals of the fluorochemical perfluorooctyl bromide, or perflubron for short. Useful as an emulsified blood substitute and for liquid ventilation, perflubron (under Alliance Pharmaceutical's brand name LiquiVent) is administered via an endotracheal tube (ETT) directly into the lungs of patients with acute respiratory failure (caused by infection, severe burns, inhalation of toxic substances, and premature birth), whose alveoli have collapsed. Once instilled, perflubron acts in two principal ways to improve gas exchange in the lung. Firstly, the gas-liquid interface present in the ordinary lung is replaced with a liquid-liquid interface allowing for more efficient transfer of Oxygen and Carbon dioxide. Furthermore, a liquid positive end expiratory pressure or "PEEP" is exerted which forces open previously closed regions of the lung creating a more homogenously respiring lung.

In 1996 Mike Darwin and Dr. Steven B. Harris proposed using cold liquid ventilation with perfluorocarbon to quickly lower the body temperature of victims of cardiac arrest and other brain trauma to allow the brain to better recover.^[13] The technology came to be called gas/liquid ventilation (GLV), and was shown able to achieve a cooling rate of 0.5 degrees Celsius per minute in large animals.^[14] It has not yet been tried in humans.

Pediatric medicine

The most promising area for the use of liquid ventilation is in the field of pediatric medicine. Current methods of positive-pressure ventilation can contribute to the development of lung disease in pre-term neonates, leading to diseases such as bronchopulmonary dysplasia. Liquid ventilation removes many of the high pressure gradients responsible for this damage. Furthermore, Perfluorocarbons have been demonstrated to reduce lung inflammation, improve ventilation-perfusion mismatch and to provide a novel route for the pulmonary administration of drugs. Clinical trials with premature infants, children and adults were conducted. Since the safety of the procedure and the effectiveness were apparent from an early stage, the US Food and Drug Administration (FDA) gave the product "fast track" status (meaning an accelerated review of the product, designed to get it to the public as quickly as is safely possible) due to its life-saving potential. Clinical trials showed that using perflubron with ordinary ventilators improved outcomes as much as using high frequency oscillating ventilation (HFOV). But because perflubron was not better than HFOV, the FDA did not approve perflubron, and Alliance is no longer pursuing the partial liquid ventilation application. Whether perflubron would improve outcomes when used with HFOV remains an open question.

Space travel

Liquid immersion provides a way to reduce the physical stress of G forces. Forces applied to fluids are distributed as omnidirectional pressures. Because liquids are (virtually) incompressible, they do not change density under high acceleration such as performed in aerial maneuvers or space travel. A person immersed in liquid of the same density as tissue has acceleration forces distributed around the body, rather than applied at a single point such as a seat or harness straps. This principle is used in a new type of G-suit called the Libelle G-suit, which allows aircraft pilots to remain conscious and functioning at more than 10 G acceleration by surrounding them with water in a rigid suit.

Acceleration protection by liquid immersion is limited by the differential density of body tissues and immersion fluid, limiting the utility of this method to about 15 to 20 G^[15] Extending acceleration protection beyond 20 G requires filling the lungs with fluid of density similar to water. An astronaut totally immersed in liquid, with liquid inside all body cavities, will feel little effect from extreme G forces because the forces on a liquid are distributed equally, and in all directions simultaneously. However effects will be felt because of density differences between different body tissues, so an upper acceleration limit still exists.

Around 1970, liquid breathing found its way into television, in alien spacesuits in the Gerry Anderson UFO series, which enabled a spaceman to withstand extreme acceleration forces.

Author Joe Haldeman, in his science fiction novel The Forever War, describes fluid being introduced into all 7 natural orifices in the human body, and one surgically-added connection, through which the thoracic cavity would be filled and drained. In such a situation, the fluid in the lungs would have to be pumped in and out to provide an inspiration/expiration cycle (total liquid ventilation). Alternatively blood could be oxygenated extracorporeally while lungs remained full of passive fluid, although this is not really liquid breathing.

Liquid breathing for acceleration protection may never be practical because of the difficulty of finding a suitable breathing medium of similar density to water that is compatible with lung tissue. Perfluorocarbon fluids are twice as dense as water, hence unsuitable for this application.

http://en.wikipedia.org/wiki/Liquid_breathing

Earth's atmosphere

2008-03-18T10:46:00.000-07:00

he Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly (by molar content/volume) 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, trace amounts of other gases, and a variable amount (average around 1%) of water vapor. This mixture of gases is commonly known as air. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night.

There is no definite boundary between the atmosphere and outer space. It slowly becomes thinner and fades into space. Three quarters of the atmosphere's mass is within 11 km of the planetary surface. In the United States, people who travel above an altitude of 80.5 km (50 statute miles) are designated astronauts. An altitude of 120 km (~75 miles or 400,000 ft) marks the boundary where atmospheric effects become noticeable during re-entry. The Kármán line, at 100 km (62 miles or 328,000 ft), is also frequently regarded as the boundary between atmosphere and outer space.

Air Conditioning through the ages

2008-03-18T10:42:00.000-07:00

Air conditioning

Origins date back to 2nd Century China and Ancient Romans

The term air conditioning most commonly refers to the cooling and dehumidification of indoor air for thermal comfort. In a broader sense, the term can refer to any form of cooling, heating, ventilation or disinfection that modifies the condition of air.^[1] An air conditioner (AC or A/C in North American English, aircon in British and Australian English) is an appliance, system, or mechanism designed to stabilise the air temperature and humidity within an area (used for cooling as well as heating depending on the air properties at a given time) , typically using a refrigeration cycle but sometimes using evaporation, most commonly for comfort cooling in buildings and transportation vehicles.

The concept of air conditioning is known to have been applied in Ancient Rome, where aqueduct water was circulated through the walls of certain houses to cool them. Similar techniques in medieval Persia involved the use of cisterns and wind towers to cool buildings during the hot season. Modern air conditioning emerged from advances in chemistry during the 19th century, and the first large-scale electrical air conditioning was invented and used in 1902 by Willis Haviland Carrier.

History

While moving heat via machinery to provide air conditioning is a relatively modern invention, the cooling of buildings is not. The ancient Romans were known to circulate aqueduct water through the walls of certain houses to cool them. As this sort of water usage was expensive, generally only the wealthy could afford such a luxury.

The 2nd century Chinese inventor Ding Huan (fl. 180) of the Han Dynasty invented a rotary fan for air conditioning, with seven wheels 3 m (10 ft) in diameter and manually powered.^[2] In 747, Emperor Xuanzong (r. 712–762) of the Tang Dynasty (618–907) had the Cool Hall (Liang Tian) built in the imperial palace, which the Tang Yulin describes as having water-powered fan wheels for air conditioning as well as rising jet streams of water from fountains.^[3] During the subsequent Song Dynasty (960–1279), written sources mentioned the air conditioning rotary fan as even more widely used.^[4]

Medieval Persia had buildings that used cisterns and wind towers to cool buildings during the hot season: cisterns (large open pools in a central courtyards, not underground tanks) collected rain water; wind towers had windows that could catch wind and internal vanes to direct the airflow down into the building, usually over the cistern and out through a downwind cooling tower.^[5] Cistern water evaporated, cooling the air in the building.

Ventilators were invented in medieval Egypt and were widely used in many houses throughout Cairo during the Middle Ages. These ventillators were later described in detail by Abd al-Latif al-Baghdadi in 1200, who reported that almost every house in Cairo has a ventillator, and that they cost anywhere from 1 to 500 dinars depending on their sizes and shapes. Most ventillators in the city were oriented towards the Qibla, as was the city in general.^[6]

In 1820, British scientist and inventor Michael Faraday discovered that compressing and liquefying ammonia could chill air when the liquefied ammonia was allowed to evaporate. In 1842, Florida physician John Gorrie used compressor technology to create ice, which he used to cool air for his patients in his hospital in Apalachicola, Florida.^[7] He hoped eventually to use his ice-making machine to regulate the temperature of buildings. He even envisioned centralized air conditioning that could cool entire cities.^[8] Though his prototype leaked and performed irregularly, Gorrie was granted a patent in 1851 for his ice-making machine. His hopes for its success vanished soon afterwards when his chief financial backer died; Gorrie did not get the money he needed to develop the machine. According to his biographer Vivian M. Sherlock, he blamed the "Ice King," Frederic Tudor, for his failure, suspecting that Tudor had launched a smear campaign against his invention. Dr. Gorrie died impoverished in 1855 and the idea of air conditioning faded away for 50 years.

Early commercial applications of air conditioning were manufactured to cool air for industrial processing rather than personal comfort. In 1902 the first modern electrical air conditioning was invented by Willis Haviland Carrier. Designed to improve manufacturing process control in a printing plant, his invention controlled not only temperature but also humidity. The low heat and humidity were to help maintain consistent paper dimensions and ink alignment. Later Carrier's technology was applied to increase productivity in the workplace, and The Carrier Air Conditioning Company of America was formed to meet rising demand. Over time air conditioning came to be used to improve comfort in homes and automobiles. Residential sales expanded dramatically in the 1950s.

In 1906, Stuart W. Cramer of Charlotte, North Carolina, USA, was exploring ways to add moisture to the air in his textile mill. Cramer coined the term "air conditioning," using it in a patent claim he filed that year as an analogue to "water conditioning", then a well-known process for making textiles easier to process. He combined moisture with ventilation to "condition" and change the air in the factories, controlling the humidity so necessary in textile plants. Willis Carrier adopted the term and incorporated it into the name of his company. This evaporation of water in air, to provide a cooling effect, is now known as evaporative cooling.

The first air conditioners and refrigerators employed toxic or flammable gases like ammonia, methyl chloride, and propane which could result in fatal accidents when they leaked. Thomas Midgley, Jr. created the first chlorofluorocarbon gas, Freon, in 1928. The refrigerant was much safer for humans but was later found to be harmful to the atmosphere's ozone layer. Freon is a trademark name of DuPont for any Chlorofluorocarbon (CFC), Hydrogenated CFC (HCFC), or Hydrofluorocarbon (HFC) refrigerant, the name of each including a number indicating molecular composition (R-11, R-12, R-22, R-134). The blend most used in direct-expansion comfort cooling is an HCFC known as R-22. It is to be phased out for use in new equipment by 2010 and completely discontinued by 2020. R-11 and R-12 are no longer manufactured in the US, the only source for purchase being the cleaned and purified gas recovered from other air conditioner systems. Several non-ozone depleting refrigerants have been developed as alternatives, including R-410A, known by the brand name Puron.

Innovation in air conditioning technologies continue, with much recent emphasis placed on energy efficiency and improving indoor air quality. As an alternative to conventional refrigerants, natural alternatives like CO₂ (R-744) have been proposed.^[9]

Airborne bacteria may play large role in precipitation

2008-03-18T10:38:00.000-07:00

A Montana State University professor and his colleagues have found evidence suggesting that airborne bacteria are globally distributed in the atmosphere and may play a large role in the cycle of precipitation.

The research of David Sands, MSU professor of plant sciences and plant pathology, along with his colleagues Christine Foreman, an MSU professor of land resources and environmental sciences, Brent Christner from Louisiana State University and Cindy Morris, will be published today in the journal "Science."

These research findings could potentially supply knowledge that could help reduce drought from Montana to Africa, Sands said.

Sands, Foreman, Morris, and Christner -- who did post-doctorate work at MSU -- examined precipitation from locations as close as Montana and as far away as Russia to show that the most active ice nuclei are actually biological in origin. Nuclei are the seeds around which ice is formed. Snow and most rain begins with the formation of ice in clouds. Dust and soot can also serve as ice nuclei. But biological ice nuclei are different from dust and soot nuclei because only these biological nuclei can cause freezing at warmer temperatures.

Biological precipitation, or the "bio-precipitation" cycle, as Sands calls it, basically is this: bacteria form little groups on the surface of plants. Wind then sweeps the bacteria into the atmosphere, and ice crystals form around them. Water clumps on to the crystals, making them bigger and bigger. The ice crystals turn into rain and fall to the ground. When precipitation occurs, then, the bacteria have the opportunity to make it back down to the ground. If even one bacterium lands on a plant, it can multiply and form groups, thus causing the cycle to repeat itself.

"We think if (the bacteria) couldn't cause ice to form, they couldn't get back down to the ground," Sands said. "As long as it rains, the bacteria grow."

The team's work is far-reaching. Sands and his colleagues have found the bacteria all over the world, including Montana, California, the eastern U.S., Australia, South Africa, Morocco, France and Russia.

The team's research also shows that most known ice-nucleating bacteria are associated with plants and some are capable of causing disease.

"Bacteria have probably been around for a million years," Sands said. "They live on the surface of plants, and may occasionally cause plant disease. But their role in rain-making may be more important."

Indeed, the implications of a relationship between rain and bacteria could be enormous, though they are yet to be proven, Sands said.

For example, a reduced amount of bacteria on crops could affect the climate. Because of the bio-precipitation cycle, overgrazing in a dry year could actually decrease rainfall, which could then make the next year even dryer.

"Drought could be less of a problem once we understand all of this," Sands said.

Sands, who earned a doctorate in pathology and bacteriology from the University of California-Berkeley, proposed the concept of bio-precipitation approximately 25 years ago, but few people believed him.

Since that time, he said, better tools have changed the research climate, because new DNA technology allows researchers to distinguish the bacteria, and giant computers allow people to do meteorological studies with satellites.

"It's fun to see something come out after 25 years," Sands said, "particularly when we knew back then it was true."

More studies must be done, though, because questions remain. For example, since the bacteria do not grow above 84 degrees, precipitation could be affected if the world's weather creeps up and reaches a cut-off point, Sands said. The researchers are also examining the bacteria to find out if they vary by region.

At any rate, a diverse group of people should be interested in the research, because bio-precipitation could affect many things.

"I want people to be fascinated by the interconnection of things going on in the environment," Sands said. "It's all interconnected."

Twister Power!!!!

2008-03-18T10:35:00.001-07:00

Storm Prediction Center.
Predicting and informing people of incomings storms, and tornados.
http://www.spc.noaa.gov/

The Tornado Timeline covers major moments in the history of Tornadoes in American History.
http://www.tornadoarchive.com/T imeline.aspx/

How A tornado is for.

Video of random tornados.
http://www.youtube.com/watch?v=UVppfnXtPZ4&feature=related/

Tornados of 2007. Just a few videos.(theres more)
http://www.youtube.com/watch?v=b0wQdRcgSoI
http://www.youtube.com/watch?v=DNL7ASvl4k4
http://www.youtube.com/watch?v=kEUXr6FMtWk

and yes even movies of tornado's. and the hight light a flying cow.

Tornado Alley

Tornadoes can occur almost anywhere in the world, but the United States is the country with the highest frequency of tornadoes. Each year there are about 1,200 tornadoes in the United States, causing about 65 fatalities and 1,500 injuries nationwide.

Tornadoes becoming more frequent in Missouri

JOPLIN, MO. (AP) -- Tornadoes in Missouri are on the rise, even if experts can't say for certain why.

National Weather Service records going back to 1956 show an average of 30 tornadoes a year in Missouri.

But the totals have been higher in recent years.

Last year the weather service counted 42 confirmed twisters in Missouri.

There have been 35 logged so far this year.

The state record was 102 tornadoes in 2006.

State climatologist Pat Guinan said it's difficult to say if climate change is linked to increasing tornado numbers since records go back only to the 1950s. The numbers could also be linked to better detection and verification.

Missouri observes Tornado Awareness Week March 10-14.

And to top it of, music from a Japanese band, name tornado.
http://www.youtube.com/watch?v=MDM0jU62EqM

Air Washing

2008-03-18T10:34:00.000-07:00

http://www.interesting.vaty.net/2006/10/air-washing.html

A truly futuristic design, an Airwash washing machine should hopefully be a common fixture in all homes by 2020. Designed by two industrial design students from the National University of Singapore, the Airwash Washing Machine won Electrolux's Design Lab Award.

Inspired by the waterfall, nature's negative ion generator, this washing machine does not use any water or detergent. It utilizes negative ions, compressed air and deodorants to clean clothes. The atmospheric air and negative ions - a natural cleansing agent - fight the dirt and bacteria. The machine can be placed anywhere at home and not necessarily in the laundry area.

Sigh! Do we really have to wait for 14 years to get our hands on this miracle washer?

Airborne bugs make rain and snow

2008-03-18T10:31:00.000-07:00

Biological organisms play a surprisingly large role in how rain and snow forms, a new study shows.

Research, published today in the journal Science, says more of these bacteria and other microorganisms seed ice formation in the atmosphere than anyone realised.

The finding could help researchers improve climate forecasts and better understand the relationship between the biosphere and climate, the authors conclude.

The discovery could also one day be used to bring rain to dry areas, says lead author Brent Christner, an assistant professor from Louisiana State University.

Scientists have long known that the ice crystals in clouds that become rain or snow need to cling to some kind of particle, called ice nucleators, to form in temperatures above minus 40°C.

But they did not realise, until now, that the most active particles involved in this process are biological ones, Christner says.

"Every snow and ice sample we've looked at, we found biological ice nucleators," he says.

"Here's a component that has been completely ignored to date."

Biological nucleators

Biological ice nucleators were discovered about 40 years ago by researchers trying to determine why frost damaged some plants but not others.

They discovered that the plants that froze were covered in bacterial plant pathogens that could capture moisture in the air and turn it into ice at temperatures as warm as minus 2°C.

Mineral ice nucleators like dust and soot can only capture and freeze the moisture at temperatures below minus about 10°C.

"It means that when cloud temperatures are in the range where inorganic matter are not active, these biological ice nucleators are active," Christner says.

The researchers have not yet determined how much precipitation is formed with these organisms.

But they found a stronger presence in snow collected from Montana and France than that collected in northern Canada and Antarctica.

Spreading plant disease

Most known ice-nucleating bacteria cause plant disease, which explains why lower levels were found in snow from Antarctica, which has no deciduous plants.

But the fact they were found discovered in Antarctica at all shows that they can be carried great distances, Christner says.

The researchers say these particles can be released by the sun's radiation, in the dust kicked up when farmers till the fields or even step on plants.

They are then carried up into the atmosphere by wind and deposited far away in rain or snow, possibly infecting plants far away.

Air pollution can prevent rainfall

2008-03-18T10:30:00.001-07:00

http://www.scienceblog.com/community/older/2000/A/200000005.html

Air pollution can prevent rainfall, reported in the 10 March 2000 issue of Science

Washington D.C. - Urban and industrial air pollution can stifle rain and snowfall, a new study shows, because the pollution particles prevent cloud water from condensing into raindrops and snowflakes. These findings are reported in the 10 March issue of Science.

The new study, by Daniel Rosenfeld, of the Hebrew University of Jerusalem, presents satellite images and measurements of "pollution tracks" downstream from major urban areas and air pollution sources such as power plants, lead smelters, and oil refineries. The tracks consist of polluted clouds that have shut off virtually all precipitation because they contain abnormally small water droplets.

The droplets' small size is caused by pollution particles that act as "seeding" sites around which cloud moisture condenses. Approximately one million small droplets must collide and coalesce in order to make a precipitation-sized drop-that is, one large enough to fall below the cloud base and reach the ground before evaporating. In polluted clouds, there are too many small droplets and not enough larger ones. These small droplets float in the air with low probability of bumping into each other and merging into raindrops. The smaller droplets are also slower to freeze into ice crystals, resulting in less sleet and snowfall.

Because urban and industrial air pollution is a significant problem in many regions of the world, Rosenfeld's findings suggest that human activity may be affecting rainfall patterns on a global scale.

These data are the first direct evidence of how urban and industrial pollution affects rainfall levels, a question scientists have debated for several decades. In fact, some previous studies have concluded that air pollution might increase rainfall, but the debate has continued due to a lack of convincing data.

"In the past, scientists had to collect information by poking little holes in clouds from airplanes, or using statistics about rainfall patterns because you can't replicate rain-clouds in the lab. Now, new satellite instruments allow us to have a comprehensive look at the problem. For the first time, we can measure cloud precipitation and microstructure simultaneously over large areas," Rosenfeld said.

In his Science paper, Rosenfeld presents the first images of pollution tracks over land. The images, taken over regions in Turkey, Canada, and Australia, all contain known sources of industrial or urban air pollution. The tracks stream away from these pollution sources in long narrow plumes.

Rosenfeld took yet a closer look at the pollution tracks in Australia, where the plumes were particularly striking. Further measurements from a bevy of satellite instruments showed that precipitation of both raindrops and ice crystals-which was occurring in the unpolluted clouds-was practically shut off in the clouds within the pollution tracks. However, the total amount of moisture in the polluted clouds was sufficient to produce rain and snow.

Rosenfeld also notes that in other parts of the world air pollution is more widespread and not as easy to distinguish as it is against the relatively clean Australian atmosphere. Thus the well-defined tracks identified in the study "serve as a Rosetta stone for the potential impact of more widely distributed aerosol pollution on clouds," writes Owen Toon, of the University of Colorado at Boulder, in a related commentary article.

Cholera: Tracking the First Truly Global Disease

2008-03-18T10:27:00.002-07:00

Cities lacked the infrastructure needed to contend with the ever growing masses. As the population swelled, so did the pestilential odors that rose from the over 200,000 cesspools across the city and from the sewage that piled up in every ditch and alleyway. The sewage overflowed into houses and marketplaces from storm-water sewers during the frequent rainstorms and at the River Thames's high tide, said Jon Schladweiler, a historian with the Arizona Water and Pollution Control Association.

Much of this waste eventually made its way into streams or directly into the Thames. In England rivers were viewed as a waste-disposal system, and the Thames became a reeking brown sewer. This scenario was pervasive across Europe. "Disease, stench, and filth were rampant in cities throughout Europe at the time," Schladweiler said.

There was a lot of confusion about the disease, as in the early days of HIV, said Ralph Frerichs, professor of epidemiology at University of California, Los Angeles. Most physicians believed the disease was contracted by breathing noxious vapors, or miasma. "There was a lot of fear, because people can't stop breathing air," Frerichs said.

But one doctor, John Snow, published another theory in 1849: Cholera was transmitted by contaminated food or water. He argued that it couldn't be airborne because it didn't affect the lungs. But his theory was ignored, attacked by many among the medical profession because he couldn't identify the "poison" in the water.

It wasn't until the 1854 outbreak that Snow was able to prove his argument. He mapped the location of cholera deaths—and found high concentrations in certain areas. For example, about 500 people died in ten days near the intersection of Cambridge and Broad Streets—they shared a single water supply.

He went to city officials with his data. "He was very concerned about transmitting this information to the public and the Board of Guardians," Frerichs said. The board, a city-council-like body, was in charge of public health, welfare, and sanitation. The pump handle from the water source was removed—and cases in the area dropped to almost none.

At that time two companies supplied the city with water from the Thames, one located upstream, the other, downstream. Snow discovered that cholera was rampant among patrons whose water originated downstream—contaminated by city sewage.

The Water Act of 1852 required that water companies filter water. In 1866 Charles Greaves, the engineer from the East London Company, admitted that water from open reservoirs and the river had been pumped directly to the city without purification—though company officials later denied it. That year 4,500 people died in East London in the country's fourth cholera epidemic.

The Great Stink

By the summer of 1858, the metropolis was wrapped in "The Great Stink." The stench from the Thames had grown so intense that thousands of residents fled the city.

Windows of the Parliament building had to be covered with curtains soaked in chloride of lime to keep the government open—but Parliament ultimately closed down because the smell became unendurable. "This was one of the few times in history it's closed," Schladweiler said.

The repeated outbreaks of disease and unbearable odors prompted city officials to build new drains, protect the water supply, construct public bathhouses—and construct proper sewers.

The sewer-building project, designed by engineer Joseph Bazalgette, linked 1,000 miles (1,600 kilometers) of street sewers to 82 miles (132 kilometers) of huge, egg-shaped sewers that fed effluent out into the open sea. This new shape kept sewage flowing, even in flat landscapes like the Thames River Valley.

With better sanitation, the cholera epidemics stopped. In 1876 the comma-shaped bacterium was discovered under a microscope by the German doctor Robert Koch. Cholera was then fully recognized as an acute bacterial infection of the intestine caused by the intake of food or water contaminated with Vibrio cholerae, usually from human feces.

Bazalgette's novel design was adopted by city planners across Europe and in the U.S. Though it had to be prompted by epidemic disease and crowded, pestilential slums, England became the leader in the sciences of urban planning and public health.

Baylor Institute for Air Science

2008-03-18T10:27:00.001-07:00

http://www.baylor.edu/bias/

BIAS for Excellence In Environmental Research, Education and Public Service

The mission of the Baylor Institute for Air Science (BIAS) is to foster stewardship of the environment through research, public service and the education of a new generation of scientist-pilots dedicated to environmental research.

The course of study is highly interdisciplinary in nature. Professors from other disciplines collaborate in providing a unique program called the Scientist-Pilot program. This program involves research and development in monitoring air quality with instrumented aircraft and alternative aviation fuels. Scientists, government agencies, and private sectors partner in the investigations. The BIAS research facilities include aircraft and engine test stands and the Renewable Aviation Fuel Development Center (RAFDC).

BIAS interacts with government and university officials world-wide regarding programs that use biomass fuels in aircraft and air quality monitoring programs using instrumented aircraft. BIAS conducts conferences, seminars and demonstrations on critical issues of air pollution, the development of renewable transportation fuels and the imperatives concerning environmental stewardship.

History of Air Pollution

2008-03-18T10:25:00.000-07:00

http://www.ace.mmu.ac.uk/eae/Air_Quality/Older/History.html

Air pollution, particularly in cities, is certainly not a new problem. Back in the Middle Ages the use of coal in cities such as London was beginning to escalate. The problems of poor urban air quality even as early as the end of the 16^th century are well documented.

In the UK the Industrial Revolution during the 18^th and 19^th centuries was based on the use of coal. Industries were often located in towns and cities, and together with the burning of coal in homes for domestic heat, urban air pollution levels often reached very high levels. During foggy conditions, pollution levels escalated and urban smogs (smoke and fog) were formed. These often brought cities to a halt, disrupting traffic but more dangerously causing death rates to dramatically rise. The effects of this pollution on buildings and vegetation also became obvious. The 1875 Public Health Act contained a smoke abatement section to try and reduce smoke pollution in urban areas.

During the first part of the 20^th century, tighter industrial controls lead to a reduction in smog pollution in urban areas. The 1926 Smoke Abatement Act was aimed at reducing smoke emissions from industrial sources, but despite the declining importance of coal as a domestic fuel, pollution from domestic sources remained significant.

The Great London Smog of 1952, which resulted in around 4,000 extra deaths in the city, led to the introduction of the Clean Air Acts of 1956 and 1968. These introduced smokeless zones in urban areas, with a tall chimney policy to help disperse industrial air pollutants away from built up areas into the atmosphere.

Following the Clean Air Acts, air quality improvements continued throughout the 1970s. Further regulations were introduced through the 1974 Control of Air Pollution Act. This included regulations for the composition of motor fuel and limits for the sulphur content of industrial fuel oil.

However, during the 1980s the number of motor vehicles in urban areas steadily increased and air quality problems associated with motor vehicles became more prevalent. In the early 1980s, the main interest was the effects of lead pollution on human health, but by the late 1980s and early 1990s, the effects of other motor vehicle pollutants became a major concern. The 1990s have seen the occurrence of wintertime and summertime smogs. These are not caused by smoke and sulphur dioxide pollution but by chemical reactions occurring between motor vehicle pollutants and sunlight. These are known as ‘photochemical smogs’.

In 1995, the Government passed its Environment Act, requiring the publication of a National Air Quality Strategy to set standards for the regulation of the most common air pollutants. Published in 1997, the National Air Quality Strategy has set commitments for local authorities to achieve new air quality objectives throughout the UK by 2005. It is reviewed periodically.

The Air Purifiers and Air Purifier Technology Today

2008-03-18T10:24:00.000-07:00

http://www.airpurifiers.com/today.htm

The air purifiers have proved to be a very useful tool in homes, hospitals, schools, and offices around the world over the last fifty years. It has helped millions of people who suffer from Asthma, Multiple Chemical Sensitivity (MCS), Environmental Tobacco Smoke (ETS), noxious gases, foul odors, and many other allergens.

For the last twenty years or so, environmental tobacco smoke (ETS) has been proven to cause a great deal of health complications. Today you can find air purifiers that can help to decrease and completely remove ETS from the air. Many of these systems are found in night clubs, bars, and restaurants due to the high volume of smokers. There are now smaller purifying units that fit comfortably into your household that can clear the air of hazardous tobacco smoke.

ETS contains very harmful particles along with hazardous to your health gaseous compounds such as hydrogen cyanide, nitrogen oxides, carbon monoxide, and carbon dioxide. Along with all of those, ETS also contains a grand amount of volatile compounds like ethane, propene, formaldehyde acetaldehyde, acetone, benzene, and acrolein. These are what cause the smell and irritation from tobacco smoke.

The systems that are designed for ETS have the effectiveness to take in particles of .01 microns in diameter. They also have a large capacity for holding such tiny particles and they also have an expansive spectrum gas filter. These types of air purifiers also have a very high air delivery due to the fact that rooms that contain ETS must be cleaned every few hours to ensure that the air is not harmful.

The development of air purifiers that could rid the air of chemicals came about during war times. Chemical warfare was a great fear and what better way to combat it than to design an air filter that could filter out all of the harmful chemicals in the air that the military breathed in.

MCS is the result of those who are very sensitive to chemicals such as carpets, additives to foods, household cleaners, fuel, fabrics, building materials, pesticides, and perfumes. MCS can result because the person has had an allergic reaction to a specific chemical or to a wide range of chemicals. Many of the symptoms are difficulty breathing, burning irritated eyes, migraines, nausea, aching joints, fatigue, or trouble sleeping. MCS is commonly found in middle aged women. Due to the chemicals that are in these types of products there are air purifiers that can reduce these effects and clear the air of the harmful particles, making it much easier for MCS sufferers to cope.

When it comes down to finding air purifiers on the market to help combat MCS, you will most likely find them very few and far between. It's not that there are none out there, it's just that the ones that are out there, can't effectively filter out gases and chemicals because the gas filter is just too small to work efficiently. More and more air purifiers are being designed with granular activated carbon filters that help to increase the air purification process of harmful chemical gases and odors. Some air purifiers may have carbon filters, but they will not remove all of the chemical gases. You should look for a unit that has an activated carbon filter to filter out the volatile organic compounds as well as the chemicals that contaminate the air causing some people to have a reaction.

Allergies and asthma are another major reason to look for an air purifier. From the start it seems as if this was one of the main reasons to create such a contraption as the air purifiers. Those who suffer from asthma tend to be affected by particles in the air. The same is true for anyone suffering from allergies. Allergens such as pet dander, dust mites, and pollen travel through the air to the sufferers lungs as they breath in. Indoor allergens tend to affect people more than outdoor ones because we tend to spend about ninety percent of our time indoors and the remaining ten percent outdoors.

Air purifiers can now combat 99.7 percent of all indoor allergens using a HEPA filter and a pre filter. The pre filter traps the larger particles and the HEPA filter takes in the remaining particles making the air much cleaner and easier to breath.

All in all, today's air purifiers have come a long way from what they were fifty years ago.

In the time of cholera

2008-03-18T10:23:00.002-07:00

Exactly 150 years ago London was in the grip of a cholera epidemic but within the space of a week in early September a doctor changed medical thinking forever.

Dr Snow was ridiculed for saying cholera was a waterborne disease

Today cholera is indelibly linked with water. However, 150 years ago it was much different.

At the end of August 1854 London's third big cholera outbreak was beginning.

The accepted thinking was that it was an airborne disease.

Within a week London physician John Snow had changed the perceived wisdom - but only after hundreds of people had died.

Dr Snow, who was 41 at the time, had already set out his water theory at conferences in 1849 and 1853 but the medical establishment was still not convinced.

During late August the outbreak was just beginning.

Paralysed

By the end of the month, the disease, which causes severe diarrhoea and vomiting, really took hold with more than 50 cases being reported on the night of 31 August.

During the next four days another 400 came to light.

With the public authorities paralysed by indecision, Dr Snow set about proving he had been right for years.

Analysing the deaths, he soon realised the outbreak was centred around a water pump at the junction of Broad Street, renamed Broadwick Street in 1936, and Cambridge Street in Soho.

He examined it on 3 September but only found minimal evidence of contamination.

I guess he [Dr Snow] was a bit of a maverick, he was ridiculed by some, but stuck to his theory and was proved right

Dr Ros Stanwell-Smith, of the John Snow Society

Instead, he went to the register of deaths and started to research where the victims lived.

Of the 89 who had died in the first two days of the outbreak all but 10 were served by the pump.

But it was those that did not live near the pump that proved Dr Snow right.

Two ladies from Hampstead, which was five miles away and was not hit by the outbreak, were among the victims.

It turned out that the pair, an aunt and niece, had water regularly transported from the Broad Street pump to drink.

Symbolic

Allied with the information, Dr Snow met with the local parish board of guardians.

On 8 September, in one of the most symbolic gestures in the history of public health, the pump handle was removed and within days new cases had dried up.

A year later the physician published a 139-page text, On the Mode of Communication of Cholera, setting out how the disease spread.

Vibrium cholerae, the cholera-causing bacteria

He paid for the document, an updated version of one he first wrote a few years earlier, out of his own pocket.

Dr Ros Stanwell-Smith, honorary secretary of the John Snow Society, said Dr Snow's work during the first week of September 150 years ago changed the way the world thought about cholera.

"Before he proved it was waterborne, the general opinion was that it came from bad air, the miasma theory.

"Using analytical methods, he was able to demonstrate that it was the sewage contaminating the water that was causing cholera. He probably stopped the second wave of the epidemic.

'Greatest'

"For me he is one of the greatest doctors in history. He gave the UK a head start in cleaning up our water supply, which then lead to the developing of the sewage system.

"I guess he was a bit of a maverick, he was ridiculed by some, but stuck to his theory and was proved right."

But for some his legacy goes beyond the field of epidemiology.

He became the first doctor to give a member of the royal family an anaesthetic during the birth of Queen Victoria's son, Prince Leopold, in April 1853.

Cholera: The facts

There are still more than 140,000 cases of cholera a year

The symptoms include severe diarrhoea and vomiting

Rehydration salts and clean water can cure cholera

Cases in the UK are rare, barely more than a handful each year

There have been seven cholera pandemics

The latest started in Indonesia in 1961

Professor Martyn Evans, principal of the John Snow College at the University of Durham, named after the doctor who was born nearby in North Yorkshire, said his expertise crossed several medical fields.

"For us he is an inspirational figure not just for his work in epidemiology but also obstetrics and as an anaesthetist.

"He was one of the country's greatest doctors although he is now more well known in the US than here."

Last year his achievements were recognised when he was voted the greatest doctor of all time in a poll by the Hospital Doctor magazine.

However, it was his work on cholera that remains his lasting legacy.

Killer

Dr Snow died before the revolution in public health he had campaigned for for so long took place.

There was another cholera epidemic in 1866 - eight years after his death.

Fellow epidemiologist Dr William Farr, who had at first disputed Dr Snow's theory, provided further evidence water was carrying the disease.

Within years great engineering projects were started in many cities to collect and treat sewage, ultimately eliminating the disease in industrialised countries, including the UK.

A girl takes her first dose of the cholera vaccine in Sudan

A spokeswoman for the Health Protection Agency said: "Cholera is not a really a problem in Britain now. There are only a handful of cases each year and these tend to be brought back by travellers."

However, the disease still remains a killer in the developing world.

The world has been fighting the seventh cholera epidemic since it was identified in Indonesia in 1961.

It soon spread across Asia, Russia and the Middle East and Africa with cholera cases topping 140,000, including 4,500 deaths, in 2002, according to World Health Organisation figures.

The WHO said: "Poor sanitation and food hygiene are the major causes of cholera in the developing world."

And with vaccines now available, the 21st century tragedy is that people are still dying from cholera.

Less than 1 in 100 cases result in death in countries with access to modern medicine but in some third world countries the death rate can top one in two.

Global Warming: 8,000 Years Ago

2008-03-18T10:23:00.000-07:00

http://www.cbsnews.com/stories/2003/09/23/tech/main574644.shtml

SAN FRANCISCO, Dec. 10, 2003

(AP) Measurements of ancient air bubbles trapped in Antarctic ice suggest humans have been changing the global climate thousands of years before the industrial revolution.

Beginning 8,000 years ago, atmospheric levels of carbon dioxide began to rise as humans started clearing forests, planting crops and raising livestock, a scientist said Tuesday. Methane levels started increasing 3,000 years later.

The combined increases of the two greenhouse gases implicated in global warming were slow but steady and staved off what should have been a period of significant natural cooling, said Bill Ruddiman, emeritus professor at the University of Virginia.

The changes also disrupted regular patterns that dominated the 400,000 years of atmospheric history that scientists have teased from samples of ancient ice.

"You have 395,000 years of history, which sets some rules, and 5,000 years that break those rules," Ruddiman said.

Ruddiman briefed reporters on his theory Tuesday at the fall meeting of the American Geophysical Union. Further details appear in the December issue of the journal Climatic Change.

Previously, scientists widely assumed it was only with the onset of the factory age that human activity had any significant effect on the global climate. The prehistoric changes in carbon dioxide and methane levels have been noted before but were attributed to natural causes, Ruddiman said.

"It's a great new idea we need to talk about and evaluate," said Bette Otto-Bliesner, a paleoclimate expert at the National Center for Atmospheric Research, who was not connected with the research.

Atmospheric levels of carbon dioxide and methane naturally fluctuate, in part because of changes in the orbit of the Earth and the resulting variations in the amounts of sunlight.

But human activity apparently thwarted expected decreases in the atmospheric concentrations of both gases. Leading the change was the revolutionary adoption, across both Europe and Asia, of agriculture and animal husbandry, Ruddiman said.

Analysis of air trapped in ice cores drilled from the Antarctic ice sheet show anomalous increases in carbon dioxide levels beginning 8,000 years ago - just as farmlands began to replace previously forested regions across Asia and Europe.

About 5,000 years ago, the ice cores reflect a similarly anomalous rise in methane levels, this time tied to increased emissions from flooded rice fields, as well as burgeoning numbers of livestock, Ruddiman said.

The prehistoric practices apparently overrode a buildup of ice that models predict should have occurred beginning 5,000 years ago.

Amber yields samples of ancient air

2008-03-18T10:18:00.000-07:00

Air bubbles trapped in 80-million-year-old amber are giving scientists an unprecedented opportunity to sample and analyze the atmosphere from the earth's Cretaceous period, when dinosaurs roamed the planet. And the preliminary results are suggesting that these creatures breathed an air far different from the atmosphere of today.

"We were able to recalculate the original concentration of oxygen,' says Robert A. Berner of Yale University, who has analyzed the samples along with Gary P. Landis of the U.S. Geological Survey in Denver. "The oxygen level appeared to be around 30 percent [of the atmosphere] as opposed to 21 percent today,' Berner said last week at the Geological Society of America's annual meeting in Phoenix.

Previously, the oldest samples of the atmosphere came from ice buried deep in the glacial cap of the Antarctic, dating back only 160,000 years--a tiny portion of the earth's 4.5-billion-year history. Scientists have therefore had to rely on indirect methods for studying atmospheric evolution.

The rock and fossil records show that oxygen first appeared in the atmosphere around 2 billion years ago and continued to increase in concentration over time. But this record reveals little about the last half billion years, when plants and animals left the seas, evolving into the complex forms of today.

Air samples from amber might help fill in this important gap, says Harvard University's Heinrich Holland, who has studied the evolution of the atmosphere and oceans. "It's very exciting because it potentially gives us the first real handle on variations of oxygen over the time scale of millions of years.'

Amber is fossilized tree resin or sap. As sap oozes out of a tree it often encases air, insects and even frogs (SN: 9/26/87, p. 205). Landis and Berner crushed their amber samples in a vacuum and analyzed the escaping gas with a quadrupole mass spectrometer.

In addition to the Cretaceous amber, which came from north-central Canada, the researchers also analyzed 40-million-year-old amber from the Baltic Sea and 25-million-year-old amber from the Dominican Rupublic. They found that oxygen in the Baltic amber equaled today's level, but the air from the younger Dominican amber contained less oxygen. However, Berner stresses that he and Landis completed these measurements only a week before the conference: "These are all very preliminary results. They need much further testing.'

Holland and others had previously thought of analyzing the air in amber, but they abandoned the idea, believing that the amber might have contaminated the trapped air over millions of years. Berner says the results show that the amber was relatively inert. Instead, the trapped air seems to contain some contamination-- in the form of suspiciously high values of carbon dioxide--from the respiration of trapped microbes.

The carbon dioxide concentration in the atmosphere has never risen above a few tenths of a percent, says Berner. But the high levels in the amber lead him to believe that microbe respiration converted oxygen to carbon dioxide. Because this process is a simple one-to-one conversion, he was able to recalculate the original oxygen in the trapped air.

Berner's results appear to mesh with the notions of modelers of the oceanatmosphere system, who have predicted that oxygen levels might have been higher during the Cretaceous period. These modelers believe that the concentration of atmospheric oxygen represents a balance between two pervasive processes on the earth: weathering of rocks and burial of organic matter. While weathering consumes oxygen, the burial of plants and animal material in the oceans causes oxygen levels to rise.

"It's a very complicated interplay, which we are just starting to understand,' says Holland. "But I think [the amber finding] fits beautifully into what we know about the burial of organic matter during the Cretaceous.'

Some researchers had suggested that oxygen concentrations could never rise much above the 20 percent mark because high oxygen levels would support world-wide forest fires. Since there is no record of such burning, says Berner, these fire estimates may need revision.

William Berry, a paleontologist at the University of California at Berkeley, believes the new oxygen measurements might help explain how the largest dinosaurs --some of which stood five stories tall--could have developed and flourished. "You begin to think about big animals having a little bit easier time,' he told SCIENCE NEWS.

Evolution on Earth

2008-03-18T10:16:00.000-07:00

The history of the Earth's atmosphere prior to one billion years ago is poorly understood and an active area of scientific research. The following discussion presents a plausible scenario.
The modern atmosphere is sometimes referred to as Earth's "third atmosphere", in order to distinguish the current chemical composition from two notably different previous compositions. The original atmosphere was primarily helium and hydrogen. Heat from the still-molten crust, and the sun, plus a probably enhanced solar wind, dissipated this atmosphere.
About 4.4 billion years ago, the surface had cooled enough to form a crust, still heavily populated with volcanoes which released steam, carbon dioxide, and ammonia. This led to the early "second atmosphere", which was primarily carbon dioxide and water vapor, with some nitrogen but virtually no oxygen. This second atmosphere had approximately 100 times as much gas as the current atmosphere, but as it cooled much of the carbon dioxide was dissolved in the seas and precipitated out as carbonates. The later "second atmosphere" contained largely nitrogen and carbon dioxide. However, simulations run at the University of Waterloo and University of Colorado in 2005 suggest that it may have had up to 40% hydrogen.[7] It is generally believed that the greenhouse effect, caused by high levels of carbon dioxide and methane, kept the Earth from freezing.
One of the earliest types of bacteria was the cyanobacteria. Fossil evidence indicates that bacteria shaped like these existed approximately 3.3 billion years ago and were the first oxygen-producing evolving phototropic organisms. They were responsible for the initial conversion of the earth's atmosphere from an anoxic state to an oxic state (that is, from a state without oxygen to a state with oxygen) during the period 2.7 to 2.2 billion years ago. Being the first to carry out oxygenic photosynthesis, they were able to produce oxygen while sequestering carbon dioxide in organic molecules, playing a major role in oxygenating the atmosphere.
Photosynthesising plants would later evolve and continue releasing oxygen and sequestering carbon dioxide. Over time, excess carbon became locked in fossil fuels, sedimentary rocks (notably limestone), and animal shells. As oxygen was released, it reacted with ammonia to release nitrogen; in addition, bacteria would also convert ammonia into nitrogen. But most of the nitrogen currently present in the atmosphere results from sunlight-powered photolysis of ammonia released steadily over the aeons from volcanoes.
As more plants appeared, the levels of oxygen increased significantly, while carbon dioxide levels dropped. At first the oxygen combined with various elements (such as iron), but eventually oxygen accumulated in the atmosphere, resulting in mass extinctions and further evolution. With the appearance of an ozone layer (ozone is an allotrope of oxygen) lifeforms were better protected from ultraviolet radiation. This oxygen-nitrogen atmosphere is the "third atmosphere". 200 – 250 million years ago, up to 35% of the atmosphere was oxygen (as found in bubbles of ancient atmosphere were found in an amber).
This modern atmosphere has a composition which is enforced by oceanic blue-green algae as well as geological processes. O2 does not remain naturally free in an atmosphere, but tends to be consumed (by inorganic chemical reactions, and by animals, bacteria, and even land plants at night), and CO2 tends to be produced by respiration and decomposition and oxidation of organic matter. Oxygen would vanish within a few million years due to chemical reactions and CO2 dissolves easily in water and would be gone in millennia if not replaced. Both are maintained by biological productivity and geological forces seemingly working hand-in-hand to maintain reasonably steady levels over millions of years (see Gaia theory).

History of flying - Why we are obsessed with flight?

2008-03-18T10:02:00.003-07:00

Ever since the time of the ancient Greeks people wanted to conquer the sky’s expanse and get from place to place by flying. Therefore, in the age of the Hellenic culture, a skilled sculptor and builder Dedal made a pair of wings out of wax and feathers. With the help of that marvelous device, he managed to take off into the air above Crete, along with his son Ikar. Ikar had gone too close to the sun, the wings had melted and Dedal’s son had died, unfortunately.
Ever since, many inventors have tried to build an aircraft that would enable man to fly. In addition to that, stand the famous drawings of the flying machine by Leonardo da Vinchi.
At first, balloons filled with heated air flew in the sky with the help of wind. Afterwards, aircrafts filled with gas ligh- ter than air flew and did not depend on the wind currents. People called them "airships"...
The French had projected and made the first successful "airship" – in French dirigeable, in English dirigible, and in Serbian dirizabl.

In 1784, a French general Meusnier had projected an elliptic-like balloon made from two layered "bags" with 79 meters in length. It carried a cabin shaped in a certain way so that it could float on water should it need to land on it. The balloon was equipped with three propellers that needed to be hand-turned by power and strength of eighty men. The general’s death in 1793 had stopped the "take off" of his balloon.
http://www.dirizabl.co.yu/images/history/leonardot.jpg

In 1830, British "father of aviation" Sir George Cayley had recognized the importance of the existence of motor power in order for flying and controlling of the aircraft to be possible. He experi- mented with a machine run by hot air that used gunpowder. He had hoped that the light steam engine would possibly advance and in a visionary way, he had foreseen the development of the internal combustion engine. The development of technology at that time did not enable Cayley to solve the problem of the force that would start and run the "airship".

Another Frenchman by the name of Pierr Jullien of Villejuif deserves the acknow- ledgments for further development of the dirigible. In 1850, he made and demon- strated a model of the "airship" that had a helm for flying and had looked more like models of the 20th century rather than like those that were made in the 19th century, after it was built.
It was Jullien’s "airship" that had inspired Henry Giffard, a French engineer and inventor, to build a dirigible of 44 meters in length, with a steam engine of 2.2 kilo- watts which was used to turn its propellers. The "case" for the passengers had hung from a wire net in which the aircraft was "wrapped".

Giffard’s first flight happened on September 24, 1852. He had traveled for almost 27 kilometers from Paris to Trappes with the speed of 10 kilometers per hour. His dirigible could fly only during calm weather because, by then, a strong enough motor, the dirigible’s starting device that would overcome everything stronger than a light breeze, had not been invented yet. Giffard, a wealthy enthusiast as he was, had projected one huge dirigible (600 meters long, the steam
engine for start off had weighed 30 tons) that was supposed to travel at the speed of 72 kilometers per hour. That sort of machine had been too expensive and had never been made.

In 1884, Charles Renard and Arthur C. Krebs had made an extended dirigible that they named "France" and this model was a real improvement in comparison to earlier models."France" was the first "airship" that was able to, in light wind, come back to its starting point from where it took off. It flew up in the air on August 9, 1884 for the first time and an electric engine run on batteries had controlled it. This flight, that lasted 23 minutes, was the first flight controlled from takeoff until landing. After that flight, "France" had flown seven more times.

During the next years, little had happened in the development of the dirigible, that is, until the appe- arance of a Brazilian man by the name of Albert Santos Dumont. He had perfected the technology of flying. He used a gasoline motor for the engine. He had 14 small "airships" that he had made and flew himself. In 1901, he had circled the Eiffel tower with his airship no.6, and with his dirigible
no.9, he regularly went to work from one place to the other.

A German general, Ferdinand von Zeppelin, was also succ- essful in the construction of "airships". In cooperation with Ludwig Deer and Hugo Eckener, von Zeppelin had his first successful flight on July 3, 1900.That kind of airship had been named zeppelin, after Ferdinand himself, and later on zeppelins were perfected and used in civilian and military air traffic and transport until 1940.
The Americans as well had participated in the whole "dirigible story". An American inventor Thomas S. Baldwin had made a 16 meter long ship, the "California Arrow, that had a Curtiss motor of 15 kilowatts in power. In 1908, he had sold it to the American military forces. This machine was the first American military airship.
A year earlier, an American journalist, Walter Wellman, tried to reach the North Pole with his dirigible but did not make it. In 1910, he, again, did not manage to fly over the Atlantic Ocean in his airship.
Nevertheless, the dirigibles had flown for more than a million kilometers in the next thirty years. They had even flown over oceans and were used in passenger transpor- tation and lives had not been lost.
Sixty years ago, count Hindenburg had, whilst running away, flown in the dirigible from Europe to the USA... his airship crashed in Lakehurst, NJ in 1937. Radio reporters and photojournalists sought through the tragedy live.
Thirty-six out of ninety-seven passengers had lost their lives... one person who had survived the fall, in despite of the accident, stated, "Dirigibles' time is yet to come. It is boring to fly by an airplane, dirigibles are exciting!"

In addition, really, time of the dirigible is only yet to come... Today, in the whole world, there are devotees and admirers of the dirigible. For instance, there is a group of scientists in Russia, which follow the thesis that the dirigible is the safest engine running airship ever built. The admirers of these airships give names to their compa- nies, sports clubs, associations, cafes, and publications after the dirigible. There are even museums that carry this name and painters who present different models of this ‘airship’ on their drawing panels.
Unusually nice post stamps with images of different types of the airship can be bought in Russia. We ourselves have named our magazine by this name. Nevertheless, will perhaps a new Meusnier, a new Giffard or Zeppelin appear and construct the airship of the future – an innovated dirigible?

"Airship of the Future" is precisely the name of a cargo airship that will be construc- ted by a German company called Cargo Lifter.The airship will be able to transport cargo weighing 160 tons at the speed of 100 kilometers per hour and at the height of 2000 meters. Filled up with 500,000 cubic meters of inflammable helium, the airship is going to be 260 meters in length. This dirigible will not be in need of a runway for take off and landing and will be more durable than conventional aircrafts. The only problem the constructors have is finding a way for transferring heavy and huge parts from the production section to the actual place where the parts are put together. "The cargo dirigible of the future" will be a balance between former bulky "airships" and light airships of today that are mostly used for commercial means.

The big dirigibles, made at the beginning of the 20th century, could carry lots of cargo, but they alone were heavy as well. The dirigibles of today are very light balloons filled up with pressured gas and therefore cannot be used for cargo transfers. The dirigible of the future will have, along with a motor, a modified solid construction for transferring cargo and a separate cabin for the crew.

The production of this airship is underway and several more years will probably pass by the time a prototype in its original size is made. In the "Cargo Lifter" company, they say that the project is of interest to the United Nations as well since the dirigible might also be used for food deliveries to endangered regions. Many people have gotten interested in the dirigible story, that is for sure. Perhaps because of nostalgia or the guiding idea of the everlasting of dirigible, the airship of the future is awaiting its promotion.

The Zeppelin Corporation constructed in 1997 an airship that took off in 2001 with a thought to use it in tourism means. The reservation of the flight ticket can be made on the internet as well.

Engineers at the Pentagon plan to "put up back in the sky" an airship similar to the one with which Hinden- burg flew to the United Stated by 2010.
Their dirigibles will be able to fly at heights above 20,000 meters and control US boundaries at sea since they will be equipped with radars that can cover around 2000 square kilo- meters.
On every June 3, in the German town of Fridrihshafen (on June 3, 1900, on the lake Konstanc near the mentioned town, count Zeppelin had taken off in his "airship") admirers of old aircrafts gather along. They are telling the world that fly- ing by planes is boring, that the view from a dirigible is much more interesting and that is why its time is only yet to come. We want to believe those people.

More than some seventy years ago in an old archived edition of the daily newspa- per ‘Politika’ it had been stated: "A German dirigible ‘Count Zeppelin’ traveling through France, Italy, Greece, Turkey, and Hungary – will fly over Yugoslavia as well."

Arctic Ice Core Drilling Reveals Ancient Air

2008-03-18T10:02:00.001-07:00

Deep ice tells long climate story
By Jonathan Amos
Science reporter, BBC News, Norwich

Carbon dioxide levels are substantially higher now than at any time in the last 800,000 years, the latest study of ice drilled out of Antarctica confirms.

The in-depth analysis of air bubbles trapped in a 3.2km-long core of frozen snow shows current greenhouse gas concentrations are unprecedented.

The East Antarctic core is the longest, deepest ice column yet extracted.

Project scientists say its contents indicate humans could be bringing about dangerous climate changes.

"My point would be that there's nothing in the ice core that gives us any cause for comfort," said Dr Eric Wolff from the British Antarctic Survey (BAS).

"There's nothing that suggests that the Earth will take care of the increase in carbon dioxide. The ice core suggests that the increase in carbon dioxide will definitely give us a climate change that will be dangerous," he told BBC News.

The Antarctic researcher was speaking here at the British Association's (BA) Science Festival.

Slice of history

The ice core comes from a region of the White Continent known as Dome Concordia (Dome C). It has been drilled out by the European Project for Ice Coring in Antarctica (Epica), a 10-country consortium.

The column's value to science is the tiny pockets of ancient air that were locked into its millennia of accumulating snowflakes.

Each slice of this now compacted snow records a moment in Earth history, giving researchers a direct measure of past environmental conditions.

Not only can scientists see past concentrations of carbon dioxide and methane - the two principal human-produced gases now blamed for global warming - in the slices, they can also gauge past temperatures from the samples.

This is done by analysing the presence of different types, or isotopes, of hydrogen atom that are found preferentially in precipitating water (snow) when temperatures are relatively warm.
'Scary' rate

Earlier results from the Epica core were published in 2004 and 2005, detailing the events back to 440,000 years and 650,000 years respectively. Scientists have now gone the full way through the column, back another 150,000 years.

The picture is the same: carbon dioxide and temperature rise and fall in step.

Microscope picture of gas bubbles in ice. Image: W. Berner/University of Bern
Like tiny time capsules, bubbles trap ancient samples of atmosphere
"Ice cores reveal the Earth's natural climate rhythm over the last 800,000 years. When carbon dioxide changed there was always an accompanying climate change. Over the last 200 years human activity has increased carbon dioxide to well outside the natural range," explained Dr Wolff.

The "scary thing", he added, was the rate of change now occurring in CO2 concentrations. In the core, the fastest increase seen was of the order of 30 parts per million (ppm) by volume over a period of roughly 1,000 years.

"The last 30 ppm of increase has occurred in just 17 years. We really are in the situation where we don't have an analogue in our records," he said.

Natural buffer

The plan now is to try to extend the ice-core record even further back in time. Scientists think another location, near to a place known as Dome A (Dome Argus), could allow them to sample atmospheric gases up to a million and a half years ago.

Some of the increases in carbon dioxide will be alleviated by natural "sinks" on the land and in the oceans, such as the countless planktonic organisms that effectively pull carbon out of the atmosphere as they build skeletons and shell coverings.

But Dr Corinne Le Quéré, of the University of East Anglia and BAS, warned the festival that these sinks may become less efficient over time.

We could not rely on them to keep on buffering our emissions, she said.

"For example, we don't know what the effect will be of ocean acidification on marine ecosystems. There is potential for deterioration," she explained.

More CO2 absorbed by the oceans will raise their acidity, and a number of recent studies have concluded that this will eventually disrupt the ability of marine micro-organisms to use the calcium carbonate in the water to produce their hard parts.

Air Timeline

2008-03-18T09:55:00.000-07:00

We are here to record history of air...

from 4.56 billion years ago to current date