Nature-What makes season change

For most places on earth, the passing of a year can bring marked changes to the weather and scenaries. What causes season to change? Couple of facts first:

1, Earth revolves around the Sun, and it takes about 365 days to complete one round (1 year).

2, Earth also rotates around its axis, and it takes about 24 hours to complete one round (1 day).

The reason for the change of seasons is that the Earth’s axis doesn’t align with the axis around which it orbits the Sun, there is a tilting angle of about 23.44 degree which remains unchanged. So, during certain days of the year when the Earth is at positions where the north celestial pole points away from the Sun, then sun light strikes north hemisphere at an angle, but south hemisphere receives direct sunlight. Countries in the northern hemisphere are in winter, while those in the southern hemisphere experience summer. Six months later, the Earth moves to the opposite position on the orbit, seasons reverse.

Watch the following Youtube video for more details.

About jlw

Junling got his PhD in Materials Engineering from University of Maryland, College Park. He is currently a Professor at Nanyang Technological University, Singapore, teaching undergraduate courses related to Quantum Mechanics.