source: www.eumetsat.org

RGB Airmass Colour Interpretation 900px

MSG1 RGB 05-06, 08-09, 05i ("Airmass")  
R = Difference WV6.2 - WV7.3  G = Difference IR9.7 - IR10.8  B = Channel WV6.2i

Recommended Range and Enhancement:

Beam         Channel         Range         Gamma     Gamma2
Red         WV6.2 - WV7.3     -25 ... 0         1.0         1.0
Green     IR9.7 - IR10.8     -40 ... +5         1.0         1.0
Blue         WV6.2         +243 ... +208     1.0         1.0

dry descending stratospheric air related to an advection jet appears in reddish colours   RGB 131, 8, 12
warm airmasses with high tropopause appear in greenish colours !    RGB 27, 114, 32
warm airmasses seen at a high satellite viewing angle appear with a bluish colour (limb cooling effect) !
cold airmasses with low tropopause appear in bluish colours !    RGB 58, 8, 126