http://www.physorg.com/news83781375.html>> (AP) -- Scientists are peering into the clouds near the top of the world, trying to solve a mystery and learn something new about global warming. The mystery is the droplets of water in the clouds. With the North Pole just 685 miles away, they should be frozen, yet more of them are liquid than anyone expected.
So the scientists working out of a converted blue cargo container are trying to determine whether the clouds are one of the causes - or effects - of Earth's warming atmosphere.
"Much to our surprise, we found that
Arctic clouds have got lots of super-cooled liquid water in them.
Liquid water has even been detected in clouds at temperatures as low as minus 30 degrees Celsius (minus 22 F)," said Taneil Uttal, chief of the Clouds and Arctic Research Group at the Earth Systems Research Laboratory of the U.S. National Oceanic and Atmospheric Administration (NOAA).
"If a cloud is composed of liquid water droplets in the Arctic, instead of ice crystals, then that changes how they will interact with the earth's surface and the atmosphere to reflect, absorb and transmit radiation," said Uttal.
"It's a new science, driven by the fact that everybody doing climate predictions says that
clouds are perhaps the single greatest unknown factor in understanding global warming."With NASA reporting that 2005 was the warmest year on record worldwide, the debate over global warming marches on, but not here. The American and Canadian scientists at the Eureka Weather Station in the northern Canadian territory of Nunavut, like the Inuit who are seeing their native habitat thaw, are beyond questioning the existence of climate change.
"If we compare the debate over the theory of evolution with the debate over the theory of global warming - global warming's a whole lot more certain at the moment," said Jim Drummond, a University of Toronto physics professor and chief investigator for the Canadian Network for the Detection of Atmospheric Change.
"By and large," he said, "we are not now arguing about whether global warming is going to happen; the argument has turned to: How big is it going to be?"Uttal, Drummond and other American and Canadian scientists recently visited Eureka, an outpost established jointly by Canada and the United States in 1947 and now equipped with instruments that sound like sci-fi inventions - the ozone spectrophotometer, for instance, or the tropospheric lidar. (A lidar, an amalgamation of "light" and "radar," uses laser light to detect atmospheric particles.)
The new technology helps to better understand the impact of clouds on Earth's surface temperature. The clouds being studied here range from six miles high to almost touching the ground.
"For a couple of decades we have known that super-cooled liquid water droplets could exist in clouds," Uttal said. "But the prevalence of it in Arctic clouds was not really known until these specialized sensors starting operating in the Arctic about eight years ago."
"The really exciting thing," she said, will be the ability to track an aerosol layer or an Asian dust cloud from their source and measure their effect on a cloud.
Uttal noted that
water clouds are more likely to warm the Arctic atmosphere than ice clouds, since the liquid clouds retain more heat radiated by the Earth's surface. "This means that the ice-to-water ratios in clouds may be very important in controlling the Arctic surface temperatures and how it melts," she said.
In Nunavut, the melting is keenly felt. "In the old days, we used to have 10 months of winter; now it's six," said Simon Awa, an Inuit leader and deputy minister for the environment of Nunavut who was on the trip to Eureka. "Every year we're getting winter later and later."
For these 155,000 people of Canada, Greenland, Russia and the United States, it means less time to hunt caribou, walrus and polar bear. Studies show that average winter temperatures have increased as much as 7 degrees in the Arctic over the last 50 years. The permafrost - ground that is continually frozen for at least two years - is thawing, imperiling polar bears and forcing other animals to migrate farther north.
The walrus have moved farther away, said Awa. "So you're taking more time out, away on the land hunting." Meanwhile, families back home are forced to eat store-bought food that is costlier and less healthy.
"The majority of the world's population hasn't really felt the global warming," said Awa. "But right now in the Arctic and in Nunavut, we're really worried because it's already affecting us. We are a thermometer of the world for what could happen."
Russ Schnell, director of Observatory and Global Network Operations for NOAA, notes that climate change is cyclical - that the planet's vegetation, over millions of years, sucks in and spits out carbon dioxide.
"All the carbon dioxide in the coal and oil was once in the air. The plants took it and it went into the oceans or into the ground - and now we're taking it back out," says Schnell.
"The cycle is the same today, only you're taking something that took 100,000 years and doing it in one hundred years," he said. "There's a point where animals can't change fast enough, there's a point where plants can't change fast enough, so they'll either compete it out or go extinct."
http://www.physorg.com/news84124233.html>> A number of researchers in recent years have reported perplexing findings of water vapour at concentrations as much as twice what they should be in and around cirrus clouds high in the atmosphere, a finding that could alter some conclusions about climate change.
A broad research effort to solve the puzzle and understand just what is occurring in cirrus clouds, wispy sheets of ice crystals 6 to 10 miles above the Earth's surface.
Part of the problem is that many atmospheric scientists have dismissed the findings as erroneous because the current understanding of atmospheric conditions and cirrus clouds would make the water vapour anomaly impossible, Baker said. Yet a number of pieces of evidence published in peer-reviewed journals and presented at scientific meetings during the last six years have supported the finding.
Clouds and particles in the atmosphere play a significant role in regulating the Earth's temperature because they help determine how much of the sun's heat and energy is reflected back into space and they trap outgoing radiation from the Earth's surface. Cirrus clouds also are important in regulating the distribution of water vapour, the most important greenhouse gas, in the upper troposphere.
Cirrus clouds form in the upper troposphere and modulate the exchange of water between the troposphere and the stratosphere. Vapour in the upper troposphere can rise into the stratosphere but tiny ice crystals can fall back toward the surface.
Outside the clouds, there are water vapour and minute atmospheric particles called aerosols, but no ice crystals. Scientists have come to expect that new ice crystals will begin to form in aerosols when vapour levels rise to the point at which they are 60 percent above equilibrium with the surrounding air. Yet measurements have shown that vapour levels can reach 90 percent to 100 percent above equilibrium without forming new ice particles.
Inside the clouds, it is expected that vapour levels above equilibrium cannot be maintained, yet evidence shows that often vapour levels are as much as 30 percent above equilibrium in large areas of clouds.
Scientists have speculated about what causes these anomalies. It is possible the aerosols might have as-yet undiscovered properties that prevent crystals from forming in some conditions, or there could be some kind of coating on the aerosols that prevents ice from forming, Baker said. There also could be some undiscovered property of ice crystals that prevents them from growing in certain conditions.
"There could be a different phase of ice at the temperatures and pressures in cirrus clouds that has a higher equilibrium for vapour," Baker said. "These are the kinds of questions for which we are trying to find answers." >>>
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