Sandy deserts depict in cyan in the Day Microphysics RGB images.
The red colour beam (VIS0.8) is smaller compared to the green and blue colour contribution. The reflectivity in the VIS0.8 channel depends mainly on the sun angle.
The reflection of short wave solar radiation measured by channel IR3.9 is very high for bare soils (sandy desert). Vegetated surfaces have a small albedo at 3.9 micrometer.
The intensity of the blue colour beam increases with temperature. Sandy deserts show very high temperatures during the summer months, therefore, the blue colour contribution is very high.
With a strong contribution of the green and the blue colour beam over sandy deserts, the resulting colour is cyan. This can be seen on the below Day Microphysics RGB image which displays Egypt and the Arabian peninsula.
Explanation of the cyan colour of sandy deserts in the Day Microphysics RGB (see also the recipe on the left side):
• With a strong contribution of the green and the blue colour beam over sandy deserts, the resulting colour is cyan.