Interpreting Water Vapor Satellite Images.
Meteorologists make extensive use of observations from radiometers that measure radiation with wavelengths of 6.7 micrometers. These images are referred to as water vapor images as the radiometers are measuring radiation emitted by atmospheric water vapor. Unlike the 11 micrometer radiometers, the water vapor radiometers measure radiation that is coming from the 200 to 600 hPa layer of the atmosphere. The gray scale represents the relative humidity of the middle and upper troposphere.
Satellite loops of water vapor images give an indication of the circulation of the middle and upper troposphere.