The Earth’s atmosphere is mainly heated by which one of the following

The Earth’s atmosphere is mainly heated by which one of the following ?

Short wave solar radiation
Reflected solar radiation
Long wave terrestrial radiation
Scattered solar radiation
This question was previously asked in
UPSC NDA-2 – 2021
The correct option is C, Long wave terrestrial radiation.
The Earth’s atmosphere is primarily heated indirectly. Incoming shortwave solar radiation (A) passes through the atmosphere with relatively little absorption, directly heating the Earth’s surface. The heated surface then emits energy in the form of longwave infrared radiation (C). Greenhouse gases in the atmosphere (like carbon dioxide, water vapor, methane, etc.) are efficient absorbers of this longwave terrestrial radiation. This absorption by greenhouse gases is the main process by which the atmosphere is heated, particularly in the lower layers (troposphere).
Reflected solar radiation (B) does not heat the atmosphere; it is simply bounced back into space or scattered (D). While scattered solar radiation contributes to diffuse light and some heating, the primary heating mechanism for the bulk of the atmosphere, especially the troposphere, is the absorption of outgoing longwave radiation emitted by the Earth’s surface – the greenhouse effect.