Without the sun there would be no weather. Sunlight is the energy which powers the worldâ€™s weather systems. By warming the air above the Earth, the atmosphere is kept in constant motion â€“ creating weather features such as wind, rain, snow, hail and thunder, as well as sunshine itself.
However, this heating takes place unevenly â€“ with some places around the world receiving more heat than others, and the amount also changing on a daily and yearly basis.
This variation in amount of heat received is caused by the curved surface of the Earth. Although the sunâ€™s rays travel to Earth in straight parallel lines, they strike different areas of the surface at different angles. The sunâ€™s rays are most direct near the Equator, where they arrive at an angle of nearly 90Â°. This means they are concentrated on a smaller area and so regions around the Equator are very hot.
Near the Poles, however, the sunâ€™s rays have to travel further through the atmosphere and they reach the surface at an indirect angle. They are therefore more spread out and have to heat a wider area. This means that the rayâ€™s are less powerful, which results in the very cold conditions we find in the Arctic and Antarctic.
This effect can be demonstrated using a torch and a piece of paper.
Hold the piece of paper upright and shine the beam of the torch onto it. This is like the sun at the Equator.
Now hold the paper at an angle to see the effect of the sun at the Poles.
Although we get these differences between the Equator and the Poles, climates can also vary considerably within these broad areas. This is because of other factors such as how close the area is to oceans and mountains, and its height above sea level.