Colour Interpretation Guide

low water clouds

Meteosat Second Generation

Dust RGB - Recipe

Red: BTD (IR12.0 - IR10.8)
Green: BTD (IR10.8 - IR8.7)
Blue: BT (IR10.8)

Low and warm water clouds

Low and warm water clouds depict in a pink colour in the Dust RGB images.

Pink contains a higher amount of red and blue combined with a lesser amount of green.

The red colour beam consists of the brightness temperature difference (BTD) IR12.0 - IR10.8. This difference is around zero for low-level opaque clouds. Given a temperature range from -4°C to +2°C, the red colour contribution is medium to high.

The BTD (IR10.8 - IR8.7) is ~(2-4 K) for low water clouds. As for the green component a strong gamma correction (with 2.5 gamma) is applied, the green signal becomes medium strong (or a little weaker).

The warmer the clouds, the higher the blue colour contribution. For warm low-level clouds, the blue colour contribution is high.

The Dust RGB image below shows pink low-level clouds over the South-Atlantic.

Dust RGB from 16 February 2016, 06:00 UTC

Explanation of the pink colour of low-level water clouds in the Dust RGB (see also the recipe on the left side):

• In case of low-level water clouds, red and blue colour beams contribute most, while the green contribution is less strong.