Observing clouds in four dimensions
While easily seen by people, the cotton-ball clouds (called shallow cumulus clouds) that drift overhead on partly cloudy days are hard for radars and many other instruments to observe and, therefore, hard to model and predict. Scientists situated six digital cameras in pairs at a distance of 6 kilometers (nearly 4 miles) from the Department of Energy's Atmospheric Radiation Measurement user facility site in Oklahoma with a spacing of 500 meters (a third of a mile) between cameras in a pair. These pairs of cameras provide stereoscopic views of shallow clouds from all sides. When scientists combine the data, they get a complete 3-D view of how the clouds change every 20 seconds. This ring of cameras makes it possible to observe these clouds in greater detail than ever before.