AIRS Maps In Motion
Cloud Fraction
This movie of cloud fraction made from AIRS data begins on September 1, 2002 (roughly 4 months after launch) to the present. Cloud fraction represents the portion of sky in each pixel that is covered by clouds, and the AIRS cloud fraction quantity shows the fraction of clouds in a 45 x 45 km area.
Satellites can measure cloud fraction over the entire atmosphere and for all types of clouds. Since most clouds reflect incoming sunlight very well and trap heat escaping from the Earth's surface, cloud fraction is an important parameter in studies of our planet's radiant energy budget.
Note that the AIRS instrument retrieves the concentrations of trace gases in the atmosphere. Clouds influence the depth of absorption lines of a trace gas in the spectrum, particularly if the trace gas concentration is high in the troposphere. For the retrieval of tropospheric trace gas columns it is therefore essential to have information on cloud cover conditions.
Cloud Fraction