Satellites measure precipitation using visible, infrared and microwave channels.
Geostationary satellite images provide the most useful data for precipitation estimates in the visible and the infrared because of the large area coverage and the high temporal repetition of the images. Microwave radiometers can also be used to estimate precipitation. Using visible and infrared information, precipitation amounts are pre- dicted by using formulas based on cloud type, percentage of area covered by cloud and a numerical factor which describes the rainfall potential of a particular cloud type. Cloud type is determined from the images by relating specific cloud features to standard cloud classifications based on surface observations. Ground measurements of rainfall have shown that the brightest clouds with the coldest cloud top temperatures produce the most rainfall.