Figure 4 – Heat Budget of the Earth

Scattering takes place by gas molecules and dust particles. This takes place in all directions, some of it earthwards and some towards space. In overall, earth receives 51 units of radiation which in turn radiates back in the form of terrestrial radiation. The details of this reflected radiation are as under:

♤ Radiated to space directly - 17 units

♤ Radiated to atmosphere - 34 units

The details of 34 units radiation absorbed by atmosphere from terrestrial radiations are as under

♤ Absorbed directly - 06 units

♤ Absorbed through convection and turbulence - 09 units

♤ Absorbed through Latent heat of condensation5 - 19 units Total - 34 units

Total units absorbed by the atmosphere are 48 (14 units insolation + 34 units Terrestrial radiation). These are radiated back into space. Thus, the total radiation returning from the earth and the atmosphere respectively is:

♤ Radiated back by earth - 17 units

♤ Radiated back by atmosphere - 48 units

Total - 65 units

These returning 65 units balance the total of 65 units received from the sun. This account of incoming and outgoing radiation always maintains the balance of heat on the surface of the earth. This is termed the heat budget or heat balance of the earth.