In this chapter the convection is studied using the 'Airmass RGB'. This RGB makes use of brightness temperature differences (BTD). The difference of water vapour channels 6.2 and 7.3 shows the distribution of moisture in the troposphere while BTD of the infrared channels 9.7 and 10.8 are related to tropopause height (total ozone concentration). Further, it incorporates the single WV channel 6.2, which shows the horizontal distribution of Upper Tropospheric Humidity (UTH).
High clouds appear in white colour, mid-level clouds in light ochre colour and cloud-free areas in dark green colour (warm air mass with high tropopause) or blue colour (cold air mass with low tropopause). A particular feature of this RGB is that dry descending stratospheric air is marked by a purple colour.
The image shows over eastern Germany blue areas that are related to dry, however, in that case warm air. Further to the West we see a purple area that is equivalent with relatively high IPV. According to the conceptual model "Enhancement of convection by PV" we recognize some convective cells. Over central Germany we observe the transition from purple to blue. That is equivalent to the western edge of the dark line in the WV image. Here we see again convection that occured according to the conceptional model "Convective cloud features at the leading edge of frontal cloud bands".
Surprising is the blue colour because we find very high precipitable water in high level of the troposphere in contradiction to the interpretation key of air mass RGBs.
Note: You can always click on the in the header to bring up the RGB-key.