Looking at the Difference Between Astronomical Seasons and Meteorological Seasons! (Credit: NOAA NCEI)
Discussion: The calendar has just passed the start of astronomical fall, also known as the fall equinox. For meteorologists and climatologists, they identify each season differently. Due to the position of the Earth in relationship to that of the sun, the date for astronomical seasons can vary by a few days; compared to meteorological seasons. Instead, meteorological seasons are based upon the annual temperature cycles of a season.
Meteorologists and Climatologists prefer to distinguish the seasons by the annual temperature cycles of each season. Each season is divided into its respective group by month. Meteorological winter starts with December and ends in February, spring starts in March and ends in May, summer starts in June and ends in August, and Fall starts in September and ends in November. This method allows for more consistent records with each season being approximately 90 days long.
Astronomical seasons have two solstices and two equinoxes which are marked by the point at which the earth’s tilt and the sun’s alignment are over the equator. The equinoxes occur when the sun passes directly overhead of the equator. The summer solstice falls on or around June 21st while the Winter Solstice falls on or around December 22nd. The Spring equinox falls on or around March 21st and the fall equinox occurs on or around September 22nd. These dates for the astronomical seasons are similar for both the Northern and Southern Hemispheres, however; the seasons are reversed in the Southern Hemisphere. According to the National Centers for Environmental Information, the length of an astronomical season can vary in length between 89-93 days. Due to this variation, climate information for each season would be hard to compare year-to-year.
Both Meteorologists’ and Climatologists’ methods of determining the seasons are useful and important to many different occupations and fields of interest. The next time an equinox or solstice is coming up, remember that the particular season it is occurring in actually started a little earlier for your fellow meteorologist or climatologist!
Photo Credit: National Weather Service
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© 2019 Meteorologist Shannon Scully