The Sun, having a very high surface temperature, radiates energy to the Earth in the form of electromagnetic radiation of almost all possible wavelengths. This is direct radiation. In addition to that, radiations scattered by the atmosphere, or reflected back from the Earth’s surface constitutes indirect component of solar radiation. These are of somewhat longer wavelength, hence of lesser energy. There is yet another component in the longer wavelength side, known as heat component. The total combination of these radiations creates the radiation field in the Earth atmosphere, which is characterized by the energy of radiation coming from different directions within different spectral ranges. The total burst barring the heat component is popularly known as solar radiation in the Earth’s atmosphere.