Input is received in the form of short-wave solar energy. This is called insolation.

Insolation is solar radiation received in the Earth's atmosphere or at its surface.

Only approximately 52 per cent of this insolation reaches the earth's surface. The rest is absorbed by water vapour, dust and clouds, or is reflected by the Earth's surface and scattered by particles in the air.

This reflection is called the albedo. The albedo of an object is the extent to which it diffusely reflects light from the Sun.

Reflected heat, in the form of long-wave radiation, is trapped in our atmosphere and keeps our planet warm. This is known as the natural greenhouse effect.

The diagram below shows this process - these figures are approximate.

Earth partially absorbing the sun's energy.