Fall, or the autumn equinox, officially arrived in the Northern Hemisphere on Thursday. The beginning of the fall means that day and night will be of the same duration, i.e. 12 hours.

Autumn equinox begins when the sun's rays strike the equator and gradually move southwards. "This change in the tilt causes the change in seasons with the northern hemisphere moving from the warmth of summer to the chill of winter," weather.com digital meteorologist Linda Lam explained. "This process includes a shift in the overall location of the jet stream, which plays an important role in weather conditions."

From the first day of the autumn equinox, daylight in the Northern Hemisphere sinks lower and nights become longer until the winter solstice. However, in the Southern Hemisphere, it is exactly opposite. In Southern Hemisphere, it marks the beginning of spring.

"Fall is a transition season and in the U.S. fall is usually characterised by large variations in temperatures, as well as an increase in low-pressure systems bringing rain, storms and even snow across the country," Lam said. "Generally in the U.S. after the fall equinox, temperatures continue to become colder and snow becomes more common."

During the shift in the seasons, the leaves change colours, but it does not happen overnight. And as you wait for the colours of the leaves to change, we bring you some beautiful photos of the fall, also called as the fall foliage season, from around the world.