Atmosphere

Question 1

Global Heat Budget

Answer 1

100% energy given by sun
46% absorbed by the surface of the Earth
23% absorbed by the atmosphere (4% clouds, 19% water vapour, gases, dust)
17% reflected by clouds
8% reflected by atmospheric gases/dust
6% reflected by earth's surface

Question 2

Global Energy Balance

Tilt of Earth

Answer 2

Depending on Earth’s angle during its orbit, certain areas will receive more energy. The variation is most extreme at the poles - approx. 6 months light and 6 months dark. However, as the sun is always overhead the tropics, there is 12hrs light and 12hrs dark all year.

Question 3

Albedo Effect

Answer 3

The poles have a high albedo due to being white in colour - acts as a mirror, reflecting heat.

The tropics have a low albedo due to the dark forests - absorbing heat.

Question 4

Curve of the Earth

Answer 4

Because its spherical, energy from the sun hits the equator at right angles, but the distance it has to travel to reach the poles is greater = weaker energy + a greater area to cover

Question 5

Thickness of Atmosphere

Answer 5

because of the curve, there is more atm. for energy to pass through at the poles and so more is absorbed by clouds, water vapour, gases etc. than at the tropics, where the atm. is thinner

Question 6

Redistribution of Energy

Answer 6

• Surplus of solar energy in tropical latitudes as this is where the sun’s rays are more concen. The rays strike the areas around the centre of the earth at right angles, the intensity of insolation is greatest. Also less atm. to pass through at tropics = less energy lost due to absorp and reflection by clouds and gas.
• At higher latitudes the rays strike surface at a wider angle, spreads heat energy over bigger surface area, therefore insolation striking surface at equator heats up smaller surface area than the same amount of insolation at higher latitudes = surplus of solar energy.
• Albedo effect makes difference. More radiation is absorbed at tropics due to amount of dark forestry. However, more radiation reflected at poles by amount of ice.