And no I don’t mean because I live in Florida, the land of hot or not-as-hot. You may have seen social Media sites buzzing with the mention of spring beginning today, March 01. Don’t worry, you’re not confused. There are indeed different definitions for spring, depending on whether or not you live in the world of meteorology or elsewhere in the “normal” world.
But before we separate the two, let’s take a step back and review the “anatomy” of the seasons.
Most people assume that the seasons are a result of the Earth’s distance from the Sun. While this initial thought is indeed intuitive, it’s counteracted with the fact that the Earth is actually closer to the Sun during the Northern Hemisphere Winter, and further from the Sun during the Northern Hemisphere Summer. Take a look!
The actual reasons we experience the seasons are a result of the Earth’s tilt. Summer and winter seasons yield the expected temperature extremes because the Earth’s tilt allows the Sun to unevenly concentrate its energy. Think of it this way: More of the solar “wealth” is given to one hemisphere [summer] at the expense of the other [winter].
Consequentially, spring and fall seasons are considered “transition seasons”; more specifically, where the position and tilt of the Earth occurs in such a way that the Sun’s energy is equally distributed between the Southern and Northern Hemisphere [spread the solar wealth, each hemisphere roughly gets the same].
So now that we share a same page of what seasons actually are, let’s get back to the original question: When does spring start? “Meteorological Winter” refers to the usual [climatological] coldest three months of the year, which means December, January, and February. Therefore “Meteorological Spring” begins right after, or today, March 1st!
The majority of the world goes by the astronomical seasons, which follows the Earth’s position around the Sun. The beginning of “Astronomical Spring”, also known as the “Vernal Equinox” requires the further understanding of what an equinox actually is.
Let’s take a quick science detour for more astronomical anatomy. The word “equinox” can be further dissected into its Latin roots; “equi” meaning “equal” and “nox” meaning “night”. Therefore, the definition of an equinox is when the day and night are of approximately equal times around the planet [roughly 12 hrs each, give or take several minutes depending on how close you live to the poles]. Going back to the “Vernal Equinox”, the position of the Earth around the sun during this time usually occurs between March 19 and March 21, and it kicks off the beginning of the calendar version of spring.
So “Happy Spring” to all my fellow scientists, and to the rest of you, catch you in a few weeks.
Meteorological Spring follows the average temperatures and begins on Mar 1.
Astronomical Spring follows the earth’s orbit around the sun and begins between Mar 19 and Mar 21