To do this, routine intercomparison of spectral instruments, such as the event that just happened in Boulder, will be an integral part of each network's operations. The spectroradiometers that were tested separate the sun's rays into distinct wavebands, much as a prism does. Most of the sun's radiation is visible light that may be separated into the colors of the rainbow. Only a small part of the solar spectrum is in the ultraviolet, which comprises higher energy wavelengths that are harmful to living things. These harmful high-energy wavelengths cannot be seen by the human eye but can be detected by sensors in these special instruments.
Clouds generally decrease the amount of ultraviolet radiation reaching the Earth's surface.
NOAA's experimental ultraviolet forecasts account for likely cloud cover and observed and predicted changes in stratospheric ozone for over 50 U.S. cities. NOAA, an agency of the U.S. Commerce Department, describes and predicts changes in the Earth's environment and promotes global environmental stewardship. As a non-regulatory agency of the Commerce Department's Technology Administration, NIST promotes U.S. economic growth by working with industry to develop and apply technology, measurements and standards. Return to NIST News Releases from the Physics Laboratory page. Return to Physics Laboratory page.