Satellite Instrument

Cloud free land surfaces appear olive green in the HRV Cloud RGB images.

Land, vegetated or bare soil, depicts in olive green colours in the HRV Cloud RGB. Due to rather high temperatures of the ground, the contribution from the blue colour beam does not play an essential role in the HRV Cloud RGB.

The HRV channel, contributing with the red and green colour beam, is responsible for the greenish colour of the soil. In fact, the red and green beam have the same intensity. A mixture of red and green normally results in yellow. In fact when yellow gets darker, i.e. the red and the green colour beam are weak but of same intensity, the human eye sees the mixture of both as a green tone.

The image below shows the African sand desert in olive green colours. Sand has a relatively high albedo while vegetated land and rocks have a smaller albedo. This can be seen in the image below which shows the sandy Saharian desert and in contrast vegetation covered land near the coast.


HRV Cloud RGB from 29 July 2015, 12:00 UTC

Explanation of the olive green colour of cloud free land surfaces in the HRV Cloud RGB (see the recipe):

Land surfaces are characterised by their albedo in the HRV Cloud RGB. Moderate red and green contributions combine to an olive green which becomes darker when the albedo reduces (e.g. vegetation).