Detailed Explanation:

The atmosphere is primarily heated through the greenhouse effect mechanism, not direct solar radiation.

Solar radiation (short-wave) passes through the atmosphere largely unabsorbed and heats the Earth's surface.

The heated surface emits long-wave terrestrial (infrared) radiation, which is absorbed by greenhouse gases (CO₂, water vapor, methane) in the atmosphere, warming it from below.

Reflected solar radiation escapes back to space and does not contribute to atmospheric heating.

This indirect heating process explains why the troposphere is warmest near the surface and cools with altitude.