Global heat budget

Question 1

Curvature of the earth’s effect

Answer 1

Due to the curvature of the earth - meaning that because the earth is a sphere and as the sun rays hit the areas around the centre of the earth at a right angle, that at the poles, the rays strike the surface at a wider angle, where as at the tropical latitudes insolation hits a smaller area despite being the same amount of insolation.

Question 2

Thickness depth of the atmosphere

Answer 2

Meaning the closer you go to the poles the bigger the amount of atmosphere the insolation has to go through. Therefore more solar energy is lost through scattering, absorption and reflection.

Question 3

Albedo

Answer 3

This means that areas such as the poles, with their ice caps being light/white have more heat loss through terrestrial radiation as they reflect heat. Meaning they have a high albedo. Where as the tropical latitudes have a low albedo as they absorb heat due to having areas of dark green and brown of forests.

Question 4

Why does the earths surface only absorb 50% of solar energy.

Answer 4

The earth’s surface only absorbs about 50% of solar energy because reflection and scattering reduces the amount of energy by about 31%. This energy is sent back into the atmosphere as long wave radiation.
Reflection therefore varies depending on cloud cover and the covering of the Earth’s surface. This is known as the albedo effect. For example, snow at the poles reflects more radiation compared to darker forest areas which absorb more incoming radiation. About 17% is reflected by clouds and 8% is scattered by gas and dust particles, whilst 6% is reflected from the Earth’s surface.
Absorption by the atmosphere reduces the solar energy by approximately 19%. This is
because 17% is absorbed by dust and gases, whilst 3% is absorbed by clouds.