Sunshine      

Without the sun there would be no weather. Sunlight is the energy which powers the world’s weather systems. By warming the air above the Earth, the atmosphere is kept in constant motion – creating weather features such as wind, rain, snow, hail and thunder, as well as sunshine itself.

However, this heating takes place unevenly – with some places around the world receiving more heat than others, and the amount also changing on a daily and yearly basis.

...at Equator

This variation in amount of heat received is caused by the curved surface of the Earth. Although the sun’s rays travel to Earth in straight parallel lines, they strike different areas of the surface at different angles. The sun’s rays are most direct near the Equator, where they arrive at an angle of nearly 90°. This means they are concentrated on a smaller area and so regions around the Equator are very hot.

Near the Poles, however, the sun’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 ray’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.  We will learn more about some of these factors in the temperature variations section.

The colourful sky

Sunlight also has an effect on the actual appearance of many weather phenomena. More information can be found by accessing the pages below:

• blue skies and red sunsets
• rainbow colours

Now you know more about the sun, would you like to carry out some experiments using what you have just learnt?  If so, let's go to the next page together!