What are the reasons for our seasons? Before we dive into the seasons, we need to understand rotation and revolution.
The Earth is an oblate spheroid (round and slightly flat at the poles). The Earth rotates one time on its axis every day. You can model this by turning around. Revolution is the movement of Earth around the Sun. The earth orbits, or revolves around the Sun one time each year.
There is a common misconception that the Earth’s distance from the sun causes seasons, but the reason for our seasons is actually the Earth’s tilt. During the northern hemisphere winter months (December-February), the Earth is tilted such that the Southern hemisphere (tropic of Capricorn 23.5 degrees south) receives direct light from the sun, and the northern hemisphere receives indirect sunlight. During summer in the northern hemisphere, the Earth is tilted such that the northern hemisphere (tropic of cancer 23.5 degrees north) receives more direct sunlight.
For more information, visit http://www.morehead.unc.edu/Shows/EMS/seasons.htm