Who Has the Warmest Summers — North or South?
You’ve probably heard that the southern hemisphere has warmer summers than the winter hemisphere because “The Earth is closer to the sun when they have summer.”
In fact, Aphelion Day this year was yesterday. That’s the day when the Earth is furthest from the sun. Our planet does not orbit in a perfect circle.
So, it makes a certain amount of logical sense that summers in the southern hemisphere would be warmer than in the northern. And a lot of people believe this.
Yeah.
We’re all wrong.
What Causes Summer and Winter
The basic cause of summer and winter is that the Earth is tilted on its axis. Earth’s axial tilt is about 23.5 degrees. This means that the Earth “leans.” Summer happens when the hemisphere you are in is tilted towards the sun and winter when it is tilted away. This tilt impacts temperature variance more than the shape of the Earth’s orbit because in addition to affecting distance, it also affects the angle at which the sun’s light hits the planet and the length of time the sun’s light shines directly (longer days).
A planet with no axial tilt would not have seasons. In the solar system, we see a fair amount of variation. The highest axial tilt is Uranus, which has an axial tilt of…