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Research / Discovery

Atmospheric scientists featured prominently in NSF special report on role of clouds in climate change

November 5, 2010

The National Science Foundation on Thursday unveiled a new multi-media package on the role of clouds in climate change that prominently features two scientists from Colorado State University's Atmospheric Science department -- one of the top atmospheric science departments in the world.

International media chats

David Randall was featured by NSF in a live chat with international media on Nov. 4, about the role of clouds in climate change.

On Thursday morning, international media were invited to chat live with David Randall, director of the NSF-funded Center for Multiscale Modeling of Atmospheric Processes known as CMMAP – a $19 million, multi-institutional Science and Technology Center based at Colorado State. Several dozen organizations and universities are members of the center with co-principal investigators at the San Diego Supercomputer Center and the National Center for Atmospheric Research in Boulder.

NSF producers also talked separately with Paul DeMott, CSU senior research scientist. DeMott, who is an atmospheric chemist, helped analyze data from 14 years of trips across the globe - from the Amazon Rainforest in Brazil to the Arctic to Broomfield, Colo. - to collect air samples, sometimes in specially equipped National Center for Atmospheric Research planes. He was a member of the Colorado State team that developed the first instrument that could be used inside a plane to take continuous air samples from in and around clouds and measure in real time the ice-forming ability of particles.

DeMott addressed a series of questions in a taped interview, including:

Paul DeMott, an atmospheric chemist, also was featured by NSF -- he addressed questions like what determines whether clouds form precipitation.

• What determines whether clouds form precipitation?
• How do you measure what’s in clouds?
• Why are ice nuclei particles so important to cloud and precipitation formation?
• How do ice nuclei impact the role of clouds in climate change?
• How could computer models better represent clouds?

Clouds and energy flows

Randall discussed the effects of clouds on energy flows and transformations, which are key to climate, and answered questions from media about how clouds affect temperature and the reliability of climate models.

“We can use our models to predict what we see now – to simulate the climatology of something like an El Nino,” Randall aid. “We run the models and compare the results with climate observations. You always find some things that look realistic and some things that are less realistic. Then you devise changes to improve the models. There’s this ongoing evolutionary process through which the models get better over time.”

The effects of clouds on energy, according to Randall, include:

• When water vapor condenses to form clouds, latent heat is “released,” like a genie from a bottle. The newly liberated heat warms the air.
• Clouds reflect sunshine back to space, cooling the Earth. This is particularly true for low stratus clouds.
• Conversely, cold high clouds, especially cirrus clouds, reduce the infrared radiating out to space. This tends to warm the Earth, and is part of the greenhouse effect.
• Clouds drop rain and snow on the surface.
• Strong updrafts in thunderstorms carry energy and moisture (and other things) from near the surface to the upper troposphere and sometimes the lower stratosphere.

Clouds cover 70% of Earth at any given time

Cloudiness affects the ocean temperature, the vertical motion of the air, and the type of vegetation.

“Observations show that clouds cover about 70 percent of the Earth at any given time,” Randall said. “The geographical pattern of clouds that we see on the Earth is affected by many things, including the geographical pattern of ocean temperature, the speed at which the air is rising or sinking on the broad scale (which varies from place to place, and with time), and the type of vegetation on the land. At the same time, cloudiness affects the ocean temperature, the vertical motion of the air, and the type of vegetation. Therefore, all of these things have to be predicted together.”

Colorado State is home to one of the top atmospheric science departments in the country, according to a recently released report from the National Research Council. The department also has been designated by the University as a Program of Research and Scholarly Excellence and is home to two of only a dozen University Distinguished Professors - Graeme Stephens and Tom Vonder Haar. Stephens and his team were at the helm of one of the very few university-led NASA Earth Science missions with the 2006 launch of CloudSat, the world's first cloud-profiling radar in orbit.

The Cooperative Institute for Research in the Atmosphere, a center international cooperation that was established in 1980 to increase the effectiveness of atmospheric research between Colorado State and the National Oceanic and Atmospheric Administration, collects and distributes CloudSat data products to scientists in countries throughout the world.

Technical web and video services were provided for NSF by Colorado State University employees Kelley Wittmeyer and Mostafa Elkady – CMMAP IT administrators – Anthony DeNardo with ACNS, and Ron Bend in Communications and Creative Services.

Contact: Emily Wilmsen
Phone: (970) 491-2336