Final answer:
The troposphere is warmed mostly by solar radiation. The Earth's surface receives radiation from the Sun through nuclear fusion, including shorter wavelength ultraviolet rays.
Step-by-step explanation:
The troposphere is warmed mostly by solar radiation. The surface of the Earth receives radiation from the Sun, which is generated through nuclear fusion. This energy is in the form of shorter wavelength ultraviolet rays, visible light, and infrared radiation.
Most of the infrared radiation emitted from the Earth is absorbed by greenhouse gases in the atmosphere, warming the Earth's surface and the lower atmosphere.