- The Heat Budget of the Earth is a balance between incoming solar insolation and outgoing terrestrial radiation.
- This balance maintains the average annual temperature of the Earth at 15 degrees Celsius.
- Solar energy received by the Earth’s surface is called solar insolation.
Heat Budget of the Earth and Atmosphere
- The solar radiation reaching the ground is called global radiation and is composed of direct shortwave radiation from the Sun and diffuse radiation scattered by the atmosphere.
- The solar energy received by the earth’s surface is converted into heat energy and heats the outer surface of the earth.
- The heated earth radiates energy in the form of long-wave radiation.
- The radiation from the sun towards the earth is called incoming shortwave solar radiation.
- The radiation from the earth towards the atmosphere is called outgoing longwave terrestrial radiation.
How is it calculated?
- Suppose incoming solar insolation is = 100 units Amount lost through scattering and reflection.
- a) Through Clouds- 27units
- b) By dust particles – 6units
- c) By Ice Caps and Glaciers- 2units
- Total 35 units are reflected back into space. (known as albedo of the earth) Now, the units received by earth and its atmosphere = 100 – 35 = 65units.
- 51 units of solar insolation are received by the earth as direct radiation which can be segregated as follows:
- (i)Received through direct Radiation= 34units
- (ii)Received as diffused day light= 17units
- Which comes out to be 51 units.