News 40 Weather Report: The science behind the first day of fall

BOWLING GREEN, Ky. – It’s the first day of fall.  That means different things to different people.

It may be as simple as leaves falling or pumpkins popping up everywhere…evening in coffee.

But there’s a scientific aspect to fall…and it’s called the equinox. The autumnal equinox, to be exact.

Equinox means “equal nights”…an occurrence that happens two days every year…the day fall begins and the day spring begins.

During the summer months, the Northern Hemisphere tilts toward the Sun, which is why our days are longer. It also helps heat up the atmosphere. 

During the winter months, the Northern Hemisphere tilts away from the Sun, which means the days are shorter and colder.

The Northern Hemisphere started tilting away from the Sun the day after summer began and the tilt will increase until the first day of winter.

The autumnal equinox is simply the halfway point between the beginning of the shortening process and the end of it. 

Which is why our daylight and darkness are equal on the first day of fall.