Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2002 March 23
See Explanation. Go online for the highest resolution available.

The Water Vapor Channel
Credit: F. Hasler, D. Chesters, et al., GOES Project, NASA/GSFC

Explanation: What alien planet's bizarre landscape lurks below these fiery-looking clouds? It's only planet Earth, of course ... as seen on the Water Vapor Channel. Hourly, images like this one (an infrared image shown in false-color) are brought to you by the orbiting Geostationary Operational Environmental Satellites' (GOES) multi-channel imagers. These instruments can produce images at the infrared wavelength of 6.7 microns or about 10 times the wavelength of visible light, recording radiation absorbed by water vapor in the upper troposphere. In this picture, the planet's dark regions correspond to high concentrations of water vapor over storms and high cloud tops, while bright areas are relatively dry. The dominant bright feature seen here is a persistent region of dry descending air extending west into the Pacific off the Peruvian coast. Atmospheric water vapor is otherwise invisible to the eye and produced by evaporation from the oceans.


Editor's note: Thanks to Don Garlick (Humboldt State Univ.) for corrections to the original text.

View this page (with external links) online at
http://apod.gsfc.nasa.gov/apod/ap020323.html.


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Official: Phillip Newman. Specific rights apply.
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