Spring may not officially begin until March 20 with the vernal equinox, but meteorologists and climatologists actually consider March 1 to be the start of spring.
It is because astronomical seasons are based on the Earth’s position relative to the sun, while “meteorological” or “climatological” seasons are divided into three-month periods based on the temperatures one would expect in each season.
For instance, summer is the most popular season, winter is the coldest season, and fall and spring are the transitional periods in between.
Thus, fairly than focusing on the orientation of the Earth relative to the Sun, these so-called meteorological seasons are classified solely on the premise of the annual temperature cycle around the globe.
The warmest three months of the 12 months within the northern hemisphere are June, July and August, so the meteorological summer runs from June 1 to August 31.
The next tweet by Alaska climatologist Dr. Brian Brettschneider shows that this definition of summer suits higher than the astronomical definition for many areas within the US and Canada.
Conversely, December, January, and February are the coldest three months within the northern hemisphere, so meteorological winter runs from December 1 to February 28 (or February 29). Brettschneider’s tweet below shows once more that this definition of winter suits higher than the astronomical definition for many of the US and Canada.
The transition seasons are three months between winter and summer, so meteorological spring runs from March 1 to May 31, and meteorological fall runs from September 1 to November 30.
Why are the seasons of the meteorological 12 months used?
Dividing the seasons into these nearly equal three-month periods makes keeping seasonal records much easier since the seasons’ start and end dates are all the time the identical.
Moreover, each meteorological season all the time lasts between 90 and 92 days, depending on whether or not it’s a bissextile year.
The dates of the solstices and equinoxes can vary by a day or two in a 12 months, so comparing seasonal temperatures or precipitation between apples and apples would turn into a nightmare for our friends on the National Weather Service in the event that they didn’t use the seasons.
This 12 months, astronomical spring will officially begin on March 20 with the vernal equinox at 5:24 p.m. EDT. It’s just the precise moment in time when the sun is precisely according to the equator.
Subsequently, in all places on Earth we’ll experience equal 12 hours of day and night on at the present time.
For the reason that Earth is tilted about 23.5 degrees from the vertical axis, probably the most direct sunlight is directed to the northern hemisphere during our astronomical summer.
Because of this the times will get longer from spring until the summer solstice on June 21. After that, the times will likely be shorter until the winter solstice on December 21, as probably the most direct sunlight shifts to the southern hemisphere during our astronomical winter.