To quote from NASA's Earth Observatory page:

"On August 17, 2009, at 1:31 p.m. EST, the latest NASA/NOAA geostationary weather satellite, called GOES-14, returned its first full-disk thermal infrared (IR) image, showing radiation with a wavelength of 10.7 micrometers emanating from Earth.

"Infrared images are useful because they provide information about temperatures. A wavelength of 10.7 micrometers is 15 times longer than the longest wavelength of light (red) that people can see, but scientists can turn the data into a picture by having a computer display cold temperatures as bright white and hot temperatures as black. The hottest (blackest) features in the scene are land surfaces; the coldest (whitest) features in the scene are clouds."

Image and more information here:

http://earthobservatory.nasa.gov/IOTD/view.php?id=39848