At the Equator, the incoming solar radiation strikes the Earth at a right angle. Hence the heat from the Sun is concentrated and more intense, and is spread over a small area. Also, at this latitude, the Sun's rays travel a short distance through the atmosphere. Because of the shorter distance travelled, Less heat is lost to the atmosphere, and therefore more of the Sun's rays reach the Earth's surface.
On the other hand, at high latitudes, the incoming solar radiation strikes the Earth at an acute angle. The Sun's rays also have to pass through a longer distance in the atmosphere before reaching the Earth's surface. Hence more heat is lost to the atmosphere. Even though the rays which strike the polar regions carry the same amount of heat as the rays which strike the tropical regions, this heat is diffused and dispersed over a large area.We all know by now that the Earth can be broadly divided into 3 climate types: tropical, temperate and polar. We also know by now that the further we travel from the Equator, the colder it gets. Hence, at the high latitudes, close to 90° North and South, temperatures are much lower than at the Equator.
Why is this so? Why is the temperature in Singapore so different from that in Greenland?
There are various reasons for this. The most important one has to do with what is known as the angle of solar incidence. Angle of solar incidence refers to the angle at which the Sun's rays strike the Earth's surface.
In summary:
• At different latitudes, the Sun's rays strike the Earth at different angles
• At the Equator, the Sun's rays strike the Earth at a right angle, hence the heat is more intense and concentrated over a small area. Less heat is lost to the atmosphere as the rays travel a shorter distance through the atmosphere.
• At the poles, the Sun's rays strike the Earth at an acute angle, dispersing and diffusing the heat over a larger area. More heat is lost to the atmosphere as the rays travel a longer distance through the atmosphere.
