(WHTM) — Spring is right around the corner and many people often see the middle of March as the beginning of the Spring season. But, did you know it also starts on March 1st?
No, you didn’t read that wrong. There are two types of seasons that start at two different times. There are the astronomical seasons and the meteorological seasons.
A question many meteorologists get (including our abc27 weather team) is why are there two and is there a difference?
According to the National Centers for Environmental Information, the astronomical seasons have been used to make time for thousands of years. The rotation of the sun forms the basis of the astronomical calendar.
The Earth’s tilt and the sun’s alignment over the equator determine both the solstices and the equinoxes. Equinoxes mark the times when the sun passes directly over the equator of the northern hemisphere. The astronomical seasons are:
- Spring Equinox: Around March 21
- Summer Solstice: Around June 21
- Autumnal Equinox: Around Sept. 22
- Winter Solstice: Around Dec. 22
These seasons are reversed when it comes to the Southern Hemisphere.
NOAA states that the elliptical shape of Earth’s orbit around the sun causes the lengths of the astronomical seasons to vary between 89 and 93 days. These variations in season length and season start would make it very difficult to consistently compare climatological statistics for a particular season from one year to the next.
That is when the meteorological seasons come into the picture.
The meteorological seasons allow meteorologists and climatologists to break the seasons up into four groups of three months based on the annual temperature cycle, as well as the calendar. The meteorological seasons do not change or vary by year. Those seasons are:
- Spring: March 1st to May 31st
- Summer: June 1st- Aug. 31st
- Autumn: Sept. 1 to Nov. 30
- Winter: Dec.1 to Feb. 28. (or Feb 29 during a leap year)
Observing and forecasting led to the creation of the meteorological seasons. They are also easier to remember, ranging from 90 days for winter of a non-leap year to 92 days for spring and summer.
This also makes it easier to figure out our seasonal statistics from the monthly statistics, both of which are very useful for agriculture, commerce, and a variety of other purposes.
