# 3b45

3b45, also known as *Alternate false color infrared*, is a basic infrared enhancement for night time use. Compared to 543b, it swaps the 12 µm and 3.75 µm channels, providing a different appearance.

On METEOR-M, the enhancement is called 456 due to the different channel numbering.

### Appearance

Land appears in various shades of orange-gray, where more orange tinged colors indicate lower surface temperature.
Clouds appear white, and progressively more cyan tinged as cloud thickness decreases.
Fog appears pale cyan, but can be hard to distinguish.
Sea appears almost black, with colder waters being progressively more gray.

### Intended usage

General purpose imagery at night.
Sea water current detections.

### Limitations

Hard to determine the cloud nature.
Very hard to detect thin clouds or fog.
Low contrast.