The water vapor in the atmosphere is the main reason for absorbing light in the near-infrared and infrared. The transmission of light for three different water-vapor levels in the wavelength range from 0.9
m to 2.5
m is shown in Figure 5. The transmittance of the atmosphere for
1.6 mm and
3 mm water vapor [TRANSA] is displayed. In the ETC three different values for the water vapor can be selected: 1.0mm, 1.6mm and 3.0mm.
Transmittance vs. wavelength for three different water vapor levels.