Wx Savvy | Science

Why Do We Have Seasons?

It's all in the tilt baby!

The reason why earth has different weather for different seasons is due to the tilt of the earth. During our summer the Northern hemisphere is tilted toward the sun. During our winter the Northern hemisphere is tilted away from the sun. This tilts causes a difference in the amount of sunlight energy we receive. Since the sun is the energy that drives weather, if you vary that sunlight amount then you vary the weather.

Without the tilt in the axis of the earth at 23.5 degrees, we would have no seasons and little to no change in our climate. Since the amount of sunlight energy would remain constant, then each location on earth would have 12 hours of sunlight and about the same temperature and weather every month. Some areas would always be cold, some always humid, some mostly rainy...and this would be the case for ever! No changes in the climate!

You might think that the seasons are due to how far earth is from the sun as we go through our yearly orbit. However, this is a pure prevarication, a fib and a lie too! The reason for the varying weather of the seasons is almost all due to the tilt of the earth and it's orbit around the sun. To prove that our distance from the sun has nothing to do with the seasons, it is around July 4th that the earth is farthest away from the sun. So we are hot here in the US while earth is farthest away from the sun. And then during our winter, around January 4th, the earth is closest to the sun.

"The sun, moon and five other stars, which are called the planets, were created by him (God) in order to distinguish and preserve the numbers of time."

- From Plato's Timaeus

Did you know that astronomers developed our calendar? They noted four very important astronomical dates: the Summer Solstice (June 22nd), the Winter Solstice (December 22nd), the Vernal (or Spring) Equinox (March 21st) and the Autumnal Equinox (September 22nd). These dates change sometimes as the alignment of the earth and sun are not consistently the same each year.

Also, these dates were chosen arbitrarily to divide our calendar into four seasons just as the twelve months that divide our year was a very arbitrary decisions. There is no law that says the calendar must be based on astronomical events, but after more than 2000 years, who are we to change the basis for the calendar?

Although the four seasons are based on the equinox and solstice dates that are well accepted around the globe, remember that other cultures and locations may have a different set of criteria to distinguish their seasons. For example, if you lived on the poles you may simply divide the year into two season: the light season and dark season. Some people consider a wet and dry season for their calendar. No matter how you divide the year, one thing is for sure, the weather changes!