What is the process Is responsible for the greatest loss of energy from earth surface into space on a clear night?

The process responsible for the greatest loss of energy from the Earth's surface into space on a clear night is radiative cooling. During the night, the Earth's surface emits infrared radiation, which escapes into the atmosphere and ultimately into space. Clear skies enhance this effect because there are fewer clouds to trap the heat, allowing more energy to be lost. As a result, surface temperatures can drop significantly under clear conditions.