The Ever Changing Seasons
The seasons on Earth have four different names (winter, spring, summer, autumn) with each indicating changes in the weather, temperature and the number of daylight hours. The seasons traditionally had a much larger impact upon the life of humans as a failed harvest, or poor summer, would often be followed by periods of famine and social unrest.
What causes the seasons?
Many people believe that Earth is closer to the sun in the summer and that is why it is hotter. And, likewise, they think Earth is farthest from the sun in the winter.
Although this idea makes sense, it is incorrect.
It is true that Earth’s orbit is not a perfect circle. It is a bit lop-sided. During part of the year, Earth is closer to the sun than at other times. However, in the Northern Hemisphere, we are having winter when Earth is closest to the sun and summer when it is farthest away! Compared with how far away the sun is, this change in Earth's distance throughout the year does not make much difference to our weather.
There is a different reason for Earth's seasons.
Earth's axis is an imaginary pole going right through the center of Earth from "top" to "bottom." Earth spins around this pole, making one complete turn each day. That is why we have day and night, and why every part of Earth's surface gets some of each.
Earth has seasons because its axis doesn't stand up straight.
Sometimes it is the North Pole tilting toward the sun (around June) and sometimes it is the South Pole tilting toward the sun (around December).
It is summer in June in the Northern Hemisphere because the sun's rays hit that part of Earth more directly than at any other time of the year. It is winten December in the Northern Hemisphere, because that is when it is the South Pole's turn to be tilted toward the sun.