What causes seasons?
At Earth’s equator, there is an equal amount of daylight and darkness each day of the year, while the amount of light and dark in other areas of Earth changes from day to day. The farther north or south you go from the equator, the greater the variation between the hours of darkness and daylight. The change in the amount of daylight and darkness during the year is due to several things: The tilt of Earth’s axis in relation to the Sun, and Earth’s rotation around the Sun.
The axis of Earth is an imaginary line through the center of Earth between the North Pole and the South Pole. Daytime and nighttime result from Earth rotation on its axis. It makes one rotation about every 24 hours. The side of of Earth facing the Sun is lighted by sunlight, so it has daylight. The side of Earth not facing the Sun receives no light from the Sun, thus it has nighttime.
Seasons are due to changes in the amount of sunlight a region receives. Because of the tilt of Earth’s axis in relation to the Sun, different regions on Earth receive a varying amount of sunlight as it makes its yearly trip around the Sun.The diagram shows four different positions of Earth which mark the beginning of four different seasons. In order from A to D, the seasons for the Northern Hemisphere are: summer, autumn, winter, and spring.
In the diagram, notice that as Earth revolves around the Sun, the most direct and the hottest rays of sunlight always strikes Earth’s surface between the Topic of Cancer and the Topic of Capricorn. The band between the Tropic of Cancer and the Topic of Capricorn is called the tropics.