Climate
Astronomical Seasons

The four seasons spring, summer, fall and winter correspond to four segments on Earth's orbit around the Sun (Astronomical Seasons). They are limited by the solstices on 21st of June and 21st of December and the equinoxes on 21st of March and 23rd of September.

Our perception of the four seasons results from the change of the angle between the sunlight and the plane of the Equator (declination of the Sun). Due to the tilt of the Earth axis to its orbital plane this angle changes by 23,5° during each season.

An observer on Earth experiences the seasons in form of the Sun's apparent path across the sky.