12.0 micron channel (12.0-12.8 )

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

• 12.0 microns.  Also in the window region.  This is called the dirty window since it is contaminated by low-level water vapor.  Hence, this channel is very useful for seeing low-level water vapor, more so than the 10.7 micron channel.
• Weighting function- at 12.0 microns, the sees the surface of the earth, but more at low-levels in the atmosphere than the 10.7 micron channel.  Hence, it is more sensitive to low-level moisture than the 10.7 micron channel.  If the atmosphere is dry, the 10.7 and 12.0 micron channels look similar.  

• 4 km resolution
• Often called the "dirty window" due to the water vapor absorption at low levels.
• This channel is more sensitive to low-level moisture due to the weighting function.  If the atmosphere is dry, the 10.7 and 12 micron channels look similar.
• Surface temperature and precipitable water products are derived form combining the 10.7 and 12.0 micron channels.
• Also used to estimate total precipitable water and atmospheric instability.
• Usually, the brightness temperatures are slightly cooler in this channel than the 10.7 micron channel due to the enhanced absorption by low-level water vapor in the 12.0 micron channel.