Breakdown: Meteorological vs Astronomical Seasons

Meteorological vs Astronomical Seasons

MEMPHIS, Tenn. (WMC) - It’s a new month and as we welcome in September we welcome in the start of Meteorological fall. You might notice that the start of this time is Sept.1. While the start to astronomical season of fall is Sept. 23.

Why the difference in 23 days? In this episode of the breakdown, we explain the reasoning of the variance in start dates for each season.

For years people have used observable periodic natural phenomena to mark time for thousands of years. That is the basis of our astronomical seasons. The natural rotation of the Earth around the sun forms the basis of our astronomical calendar, in which we define seasons with two solstices and two equinoxes. Earth’s tilt and the sunlight alignment over the equator determine the variance of seasons.

Seasons
Seasons (Source: NOAA)

With the exact dates of the start to winter, spring, summer and fall, it can be rather difficult to keep constant climatological statistics for a particular season from one year to the next. With that in mind, meteorological seasons were born.

Meteorologist and climatologists break the seasons down into groupings of three months based on the annual temperature cycle as well as our calendar. Generally, we describe winters as the coldest time of the year and summers as the warmest, with transitional seasons being spring and fall.

Meteorological spring includes the months of March, April and May; meteorological summer include June, July and August; meteorological fall includes September, October and November, leaving meteorological winter to include December, January and February.

The length of meteorological seasons ranges from 90 days for a non-leap year to 92 days for spring and summer. By following the civil calendar more and having less variation in season lengths and season start dates, its much easier to calculate seasonal statistics from monthly statistics, both of which are very useful for agriculture, commerce and other various purposes.

All this information can be attributed to the National Centers for Environmental Information which is a part of NOAA.

Now next time you wonder, why should we care about Meteorological Seasons, know its how we keep stats for years to come.

Copyright 2019 WMC. All rights reserved.