# 124

124, also known as *Cloud RGB*, is an enhancement designed to make clouds stand out more compared to surface features, while keeping the color scheme close to nature and easy to understand even for the general public.

The name 124 comes from the usage of AVHRR channel 1 (0.862 µm) in the red position, channel 2 (0.63 µm) in the green position, and infrared channel 4 (10.8 µm) in the blue position.

### Appearance

Land appears green-bluish tinge (vegetated areas) or green-yellowish tinge (deserts), while sea appears dark purple black. 
Snow and ice appear pale yellow, with melting snow having a more reddish tone
Mid and low level clouds appear yellow. Thick high level clouds appear white. Thin high-level clouds appear bluish. 

### Intended usage

Meteorology (cloud detection and characterization at daytime).

### Limitations

Low level clouds, medium level clouds and snow have similar colors.
Low contrast between vegetated and desert areas.
Vegetation information is dependent on temperature.

### References

* [EUMETSAT Training Module - Cloud RGB](https://resources.eumetrain.org/data/4/461/navmenu.php?tab=5&page=1.0.0)