What is Seasons? | Types, Definition, Structure, Function & Facts

What is Seasons?

We divide a year into four seasons: spring, summer, autumn, and winter. Each season lasts 3 months, in which summer is hottest, winter is coldest, alternating between spring and autumn.

The seasons have a lot of impact on what happens on earth. In the spring, animals are born and plants come to life. The summer is hot and that’s when the kids usually get off school and we go on vacation to the beach. Usually the crops are harvested in late summer. In the fall, the leaves change color and fall off the trees and school resumes. Winters are cold and snowy in many places. Some animals, like bears, hibernate in winter while others, like birds, migrate to warmer climates.

Why do Seasons Occur?

The seasons are caused by the changing relationship between the Earth and the Sun. The Earth revolves around the Sun called an orbit, once a year or 365 days. As the Earth orbits the Sun, the amount of sunlight received each day at each location on the planet will vary slightly. This change brings the seasons.

The Earth is Tilted

Not only does the Earth revolve around the Sun every year, but the Earth rotates on its axis every 24 hours. This is called a day. However, the Earth does not rotate directly up and down relative to the Sun. It’s slightly tilted. Scientifically, the Earth is tilted 23.5 degrees from the plane of its orbit with the Sun.

Why does our Tilt Matter?

The tilt has two main effects: the angle of the Sun relative to the Earth and the length of the day. For half a year, the Earth is tilted so that the North Pole points more towards the Sun. As for the other half, the South Pole faces the Sun. When the North Pole is tilted toward the Sun, the day in the northern part of the planet (north of the equator) receives more sun, or the days are longer and the nights are shorter. With longer days, the northern hemisphere warms up and becomes summer. As the years pass, the Earth’s tilt changes towards the North Pole moving away from the Sun, creating winter.

For this reason, the seasons north of the equator are opposite to those south of the equator. When it’s winter in Europe and the United States, it’s summer in Brazil and Australia.

We talked about how the length of the day changes, but the angle of the Sun also changes. In the summer, sunlight hits the earth more directly, energizing the Earth’s surface and heating it up. During winter, sunlight hits the Earth at an angle. This provides less energy and heats the Earth less.

Longest and Shortest Days

In the Northern Hemisphere, the longest day is June 21 while the longest night is December 21. In the Southern Hemisphere it is the opposite, the longest day is December 21 and the longest night is June 21. There are two days in the year when day and night are exactly the same. Those are September 22 and March 21.