The detection of physical parameters, such as total column water vapor, rain rate, and snow and ice cover, relies upon signatures that can often be identified in microwave imagery alone. The imagery highlights some of the atmospheric (water vapor, cloud, and precipitation related) and surface signatures key to most product algorithms. Product algorithms employ techniques that range from the purely empirical to the physical, and even a mix of both. Despite these different techniques, the underlying principles remain the same.

While the emphasis is on channels from NOAA's AMSU instrument, very similar channels from the DMSP's SSM/I instrument could be used to demonstrate the same signatures and physical quantities described here.