Nighttime Microphysics RGB The distinction between low clouds and fog in satellite imagery is challenging. While the difference between the 10.4 and 3.9 μm channels has been a regularly applied product to meet aviation forecast needs, the Nighttime Microphysics (NtMicro) RGB adds another channel difference (12.4- 10.4 μm) as a proxy to cloud thickness and repeats the use of the 10.4 μm thermal channel to enhance areas of warm (i.e. low) clouds where fog is more likely. The NtMicro RGB is also an efficient tool to quickly identify other cloud types in the mid and upper atmosphere.