When Do Seasons Start -

This is the definition most of us learned in school. It is based on the position of the Earth in relation to the sun. Because the Earth's orbit isn't a perfect circle, these dates can shift slightly each year (usually by a day or so).

"Defining seasons: a quantitative approach to the onset of spring, summer, autumn, and winter" (or similar — but the classic reference below is key) when do seasons start

Meteorologists and climatologists use a different system. Instead of looking at the stars, they look at the thermometer. They break the year into four three-month periods based on the annual temperature cycle. This is the definition most of us learned in school

Usually March 20 or 21 . On this day, the sun passes directly over the equator, making day and night nearly equal in length. "Defining seasons: a quantitative approach to the onset

It happens every year: you wake up one day expecting crisp fall air or blooming spring flowers, only to realize... wait, isn't it still summer?

Menzel, A., & Fabian, P. (1999). "Growing season extended in Europe." Nature , 397(6721), 659.