|Masterpiece of the Sky||
|Who Are NASA's Earth Explorers?
The elementary school student questioning if El Niño occurs anywhere besides the Pacific Ocean. The researcher investigating connections between Arctic ozone depletion and global climate change. The citizen scientist interested in how changing land cover and use affects animal migration patterns. And the businessperson projecting future needs for harvest, delivery and storage of crops. All of these people are Earth Explorers -- they are all connected by their curiosity about Earth system processes. This monthly series will introduce you to NASA Earth Explorers, young and old, with a variety of backgrounds and interests.
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It's likely that science, more so than art, was on the mind of amateur meteorologist Luke Howard when he introduced a system for classifying and naming clouds in 1802. Regardless of his intent, Howard's organization scheme may have provided guidance for 19th-century painters striving to depict clouds realistically.
Image to left: Artist and scientist Graeme Stephens stands with some of his artwork. Credit: William Cotton
More than 200 years later, scientists are the ones struggling to paint an accurate picture of one of nature's most ubiquitous yet mysterious elements.
Colorado State University's Graeme Stephens is uniquely familiar with both the scientific and artistic sides of clouds. While spearheading the development of CloudSat, a NASA satellite designed to observe clouds at an unprecedented level of detail, the CSU professor of atmospheric science has painted a series of oil-on-canvas pictures featuring a variety of cloud types. Most hang in the halls of CSU, some decorate NASA's Jet Propulsion Laboratory and others have been sold to private collectors.
Earth's ever-changing atmosphere has long been at the crossroads of art and science. It was an artist's book -- Eric Sloane's "Clouds, Air and Wind," published in 1941 -- that was adapted into a basic weather manual for U.S. military pilots. Poets and philosophers have also been known to reflect upon clouds and the sky above.
"Art and science have much in common, and much has been written about the common threads between both," said Stephens, who wrote such an article for American Scientist magazine. "Both, after all, are different expressions of the natural world around us."
Clouds have appeared in paintings and drawings all the way back to biblical times. But 19th-century English landscape artists Joseph Turner and John Constable were among the first to illustrate clouds with serious attention to scientific detail. The latter often noted specific weather conditions on the backs of his canvases.
Some historians believe that Howard's classification system, which described the appearance of clouds using words such as cumulus, Latin for "heap," and cirrus, Latin for "curl of hair," may have influenced artists of the time to represent clouds with greater accuracy. More recently, Stephens credits the 200-year anniversary of the system's debut with motivating him to take up painting again in 2002 after a 20-year hiatus.
During the preceding two decades, advances in technology and scientific understanding led Stephens to propose the idea of CloudSat, which is scheduled to launch no earlier than February from California's Vandenberg Air Force Base.
On the technology front, radar was introduced as a tool for studying clouds in greater detail; previously, it had been used mainly to track precipitation and aircraft. Meanwhile, scientists were becoming increasingly convinced that clouds were an important factor affecting their ability to predict climate change.
Image to right: Cirrus at Sunset, by Graeme Stephens. Credit: Chris Chrissotimos
There were a lot of questions that needed to be answered about clouds. Was their net effect to cool Earth by blocking light from the sun? Or was it to warm Earth by absorbing and re-emitting outgoing radiation from the surface? What percentage of clouds produces precipitation? Would a warmer planet increase the presence of certain kinds of clouds while decreasing that of others?
With motive and means for improving the way satellites observe clouds, Stephens invented the CloudSat mission to help answer these and other questions. Electromagnetic pulses from the Cloud Profiling Radar, the satellite's centerpiece instrument, will penetrate the outer surfaces of clouds to examine their inner workings, making CloudSat the first satellite able to see clouds and precipitation at the same time.
"Our ability to forecast clouds and rainfall from clouds is poor and is a weak link in all weather and climate modeling," Stephens said. "We cannot tell you today what fraction of the clouds that cover Earth produce precipitation, let alone how clouds and the precipitation from clouds will change with future climate change."
The path of CloudSat's orbit will be close to that of several other Earth-observing satellites. These satellites are known as the "A-Train." They are designed to work together to better understand Earth's climate. The data they collect will be combined and used in models that predict weather and climate change. One of these satellites, CALIPSO, will be launched on the same rocket as CloudSat.
If all goes as planned, scientists will soon be one step closer to painting a more accurate portrait of clouds and the Earth's water cycle, one that even Stephens the artist can be proud of.
Whether viewing the sky as a scientist or as an artist, Stephens says he appreciates all kinds of clouds. High or low, thick or thin, they all have an impact on our climate and a place in his artwork. Most of all, he says he enjoys "the way clouds of all types interact with light, producing the wonderful skyscapes we see as we look upwards."
See previous Earth Explorers articles:
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CloudSat Art Gallery
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Earth As Art
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Dan Stillman, Institute for Global Environmental Strategies