Q&A of the Day – The Difference Between Meteorological & Astronomical Seasons
Each day I feature a listener question sent by one of these methods.
Email: brianmudd@iheartmedia.com
Social: @brianmuddradio
iHeartRadio: Use the Talkback feature – the microphone button on our station’s page in the iHeart app.
Today’s Entry: Today’s Q&A stems from a previous question from a listener in addition to a recent conversation with Joel Malkin wanting to know why there’s seemingly two different dates for the beginning and end of seasons.
Bottom Line: By the time you wake up tomorrow it will be fall...regardless of the way you prefer to account for the change in seasons. At 2:50 am the Autumn Equinox, aka the astronomical fall season, commences. For some though (meteorologists), the fall season kicked off at the start of September. So, what’s the difference between meteorological and astronomical seasons? Is there any point in having a distinction between the two? Let’s take a look at it...
There’s a short and straight forward explanation offered by NOAA for the difference between the two: The astronomical seasons are based on the position of Earth in relation to the sun, whereas the meteorological seasons are based on the annual temperature cycle. Two different types of science. Two differing perspectives on the timing of the change in seasons. For the most part our society pays deference to the astronomical perspective to seasons as opposed to the meteorological point of view. With that said, both are scientifically acceptable. More specifically, here’s what’s behind how each of the seasons is determined.
Astronomical seasons are determined by Earth’s rotation around the sun. During the course of the year there are two solstices and two equinoxes. The two solstices, summer and winter, happen when the tilt of the earth's rotation is at its maximum towards the sun, in the case of the summer, and when it’s the furthest away from the sun in the case of winter. The two equinoxes, Vernal and Autumnal, which represent the onset of the spring and fall seasons, are the two moments of the year when the Earth’s axis isn’t tilted towards or away from the sun.
Meteorological seasons, which are preferred by climatologists, coincide with the 1st day of the first month of quarterly temperature changes. Metrological winter runs from December 1st through the last day of February. Meteorological spring picks up March 1st and runs through May 31st. Summer runs from June 1st through August 31st with fall lasting from September 1st through November 30th.
If you’re like most, you observe the astronomical accounting of our seasons (that is if you’re inclined to pay attention to the literal changing of them – more on that in a moment). That’s reflected with calendars commonly opting to depict the start of astronomical seasons. Also, a generic search online will point you towards the astronomical timeline for our seasons as well. But for some they aren’t so hung up on the official starts of seasons. For many the seasons change with events that are associated with seasonal change.
A couple of years ago 538 polled on seasonal changes. What they found is that over a third of people observe seasonal changes through seasonal events. For these people spring starts “when buds appear on trees (37%), fall starts when the color of the leaves start changing (25%), summer starts the day after Memorial Day (40% - which does occasionally coincide with the start of meteorological summer) and winter starts on Black Friday (23%). As for me, I’m a traditionalist in seasonal observations. My preference is the astronomical changing of the seasons. So happy fall to you! Tomorrow morning.