What two effects are responsible for the attenuation of infrared radiation as it passes through the earth's atmosphere?

The attenuation of infrared radiation as it passes through the earth's atmosphere is primarily influenced by absorption and scattering.

Absorption occurs when molecules in the atmosphere, such as water vapor, carbon dioxide, and other gases, take in the energy of the infrared radiation. This process reduces the intensity of the infrared waves as they travel through the atmosphere, effectively diminishing their strength by converting some of that energy into heat.

Scattering refers to the redirection of infrared radiation when it encounters small particles or droplets in the atmosphere. This scattering can cause the radiation to diffuse in various directions, resulting in a decrease in the direct transmission of the radiation. Both of these processes—absorption and scattering—are key in determining how much infrared radiation can reach the surface of the Earth and how it is perceived in infrared sensing applications.

In contrast, reflection and diffraction do not primarily contribute to the attenuation of infrared radiation in this context, and scintillation, while relevant in other forms of wave propagation (like radio waves), is not applicable to the infrared spectrum in the same way. Thus, absorption and scattering are the correct effects to consider for this phenomenon.