Why are the commonly chosen infrared remote sensing bands between 8~14um and 3~5um?

The atmosphere has scattering and absorption effects on electromagnetic radiation, so when selecting remote sensing bands, bands with small scattering and absorption effects, that is, the atmospheric window, will be selected.

Water vapor molecules are the main absorbers of infrared radiation. Strong water vapor absorption bands are located at 0.71~0.735μm, 0.81~0.84μm, 0.89~0.99μm, 1.07~1.20μm, 1.3~1.5μm, 1.7~2.0μm, 2.4~3.3μm, 4.8~8.0μm. The absorption band of carbon dioxide appears at 13.5~17μ. The gaps between these absorption bands form some infrared windows.

It can be seen from this distribution that the 3-5μm and 8-14μm bands have small absorption and are ideal thermal infrared remote sensing bands.