direct shortwave radiation

Direct shortwave radiation refers to solar radiation that reaches Earth's surface without being absorbed or scattered by the atmosphere. This is the portion of sunlight that appears as the Sun's distinct disk. In contrast, diffuse radiation is scattered by atmospheric molecules, such as during overcast conditions.1

The Sun emits shortwave radiation, primarily in the ultraviolet and visible light spectrum, with wavelengths typically between 0.39 and 0.76 micrometers. This energy warms the Earth's surface. While some shortwave radiation is absorbed by atmospheric gases, most of it reaches the ground, where it is either absorbed or reflected back into the atmosphere. The amount of solar radiation reaching the surface varies based on factors like latitude, time of year, and the orientation of the land.1