Solar Radiation On Earth Surface

The solar radiation that reaches the earth s surface without being diffused is called direct beam solar radiation.

Solar radiation on earth surface.

Calculating solar energy to surface energy from sun to earth. It is measured on a surface perpendicular to the rays one astronomical unit au from the sun roughly the distance from the sun to the earth. The solar constant g sc is a flux density measuring mean solar electromagnetic radiation solar irradiance per unit area. Solar irradiance is the power per unit area received from the sun in the form of electromagnetic radiation as reported in the wavelength range of the measuring instrument.

The solar irradiance is measured in watt per square metre w m 2 in si units solar irradiance is often integrated over a given time period in order to report the radiant energy emitted into the surrounding environment. If the extraterrestrial solar radiation is 1367 watts per square meter the value when the earth sun distance is 1 astronomical unit then the direct sunlight at earth s surface when the sun is at the zenith is about 1050 w m 2 but the total amount direct and indirect from the atmosphere hitting the ground is around 1120 w m 2. The sun is generally considered to produce a constant amount of power although there are small variances in the output energy depending on sunspot cycles with a surface intensity of expressed in units of power per unit area as the sun s rays spread into space this radiation becomes less and less intense as an inverse square law. This intense solar radiation as it is known in physical geography originates in the sun s core and is eventually sent to earth after convection the vertical movement of energy forces it away from the sun s core.

Cloud cover air pollution latitude of a location and the time of the year can all cause variations in solar radiance at the earth s surface. It takes approximately eight minutes for solar radiation to reach the earth after leaving the sun s surface. This is called diffuse solar radiation. Solar radiation reaches earth s surface as 1 direct beam solar radiation 2 diffuse solar radiation and 3 reflected radiation which can be neglected.

Solar radiation at the earth s surface varies from the solar radiation incident on the earth s atmosphere. Atmospheric conditions can reduce direct beam radiation by 10 on clear dry days and by 100 during thick.