Seasons

Ian Britton - Freefoto.com
Spring	Summer
Autumn	Winter

The cycles of life on Earth are bound to the seasons. In the summer it is warm, the Sun is high in the sky and the days are long. In winter it is cold, the Sun is low in the sky and the days are short.

Days vary in length throughout the year due to the tilt of the Earth.

The Earth receives many types of electromagnetic radiation from the Sun. The important two are light and heat (infra red). For six months of the year the Northern hemisphere is titled towards the Sun. Radiation from the Sun arrives from almost above our heads. For the other six months the northern hemisphere is tilted away from the Sun. Radiation from the Sun arrives at angle.

Because of this
a) it is much more spread out over a larger area so it is less concentrated and
b) it passes through a much thicker amount of atmosphere so more of it is absorbed before it reaches the Earth.

Shine a torch on a piece of paper. Now turn the paper through 45 degrees so that the light hits it an angle. How does this explain why it is colder in the winter?