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27 July 2011

SA Weather Satellite Images: 27 July 2011 08h00 SAST


Airmass is an RGB composite based upon data from infrared and water vapour channels from Meteosat Second Generation. It is designed and tuned to monitor the evolution of cyclones, in particular rapid cyclogenesis, jet streaks and PV (potential vorticity) anomalies. Due to the incorporation of the water vapour and ozone channels, its usage at high satellite viewing angles is limited. The Airmass RGB is composed from data from a combination of the SEVIRI WV6.2, WV7.3, IR9.7 and IR10.8 channels


The main application of the Snow RGB is the detection of fog / low clouds and snow during day-time. In this color scheme snow appears red because of the strong absorption in the NIR1.6 and IR3.9 channels (no green and blue), while fog / low clouds appear whitish. Small particle ice cloud appears orange, while large particle ice cloud appears with greater red component. Snow on the ground appears as full red, because its grains are usually much larger than cloud ice particles.

Images: Eumetsat (Click on images for larger view.)