Near Infrared Channel - 3.9 microns - Reflective Properties

http://www.meted.ucar.edu/satmet/goeschan/#

• During the daytime, the 3.9 micron channel receives both solar and IR radiation
• Reflected solar radiation depends on: 1) phase of water, and 2) size of particles
• Small water drops (fog/low stratus/haze) are much more reflective than large ice particles (cirrus).
• Hence, daytime thick stratus will look warmer at 3.9 microns than at 10.7 microns due to the added reflected solar radiation at 3.9 microns.
• Cirrus will also be slightly warmer at 3.9 microns during the day.
• Accordingly, you can distinguish between ice low reflectivity) and water clouds (high reflectivity) when combined with the 10.7 micron channel.