Monday is the first day of autumn. This is according to the chart of astronomical seasons and the little calendar here at my desk. Sept. 22, astronomers believe, is the first day of the fall season this year. Astronomers also believe, ridiculously, that it lasts until Dec. 21, the first day of winter.
The rest of us in the Northern Hemisphere are expected to go along with this.
Anyone who spent any time outside in the past couple of weeks knows full well that wasn’t summer. Astronomers, being scientists, may not be spending enough time outdoors.
Also being scientists, however, they do have plenty of data to back themselves up. The Earth, so claim the astronomers, travels around the sun, and it does so on a tilted axis. On that orbital path, the summer and winter solstices are the dates when our hemisphere is angled closest and farthest from the sun, or June 21 and Dec. 21, respectively. The equinoxes, at March 21 and Sept. 21, are the times of equal balance in between. Those four dates more or less mark the changes of season on the modern Gregorian calendar.
The problem, of course, is this doesn’t work.
Any child in Chicago can tell you, from deep inside a parka, that while standing outside on Dec. 20, he or she is standing outside in winter. Fall ended with the Thanksgiving days off from school. Summer — and this is key — begins when the pools open and ends when the pools close.
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Simplify a step further and we get what everyone knows anyway: Summer is the months of June, July and August. Fall is September through November. Winter gets December to February. Spring is March, April, May. Spring gets shortchanged every year in March, but that’s the system.
Meteorologists, it seems, have known this all along, or at least since 1780. That’s when the Societas Meteorologica Palatina — an early international organization for meteorology with farsighted opinions but inferior lobbyists to the astronomers — got together in Mannheim, Germany.
These early weathermen defined seasons as just those groups of months, with autumn beginning Sept. 1, winter on Dec. 1 and so on, basing everything on the cycle of temperatures, not the charting of the sun. For the Southern Hemisphere, those dates get reversed, with spring beginning Sept. 1 and so on.
Meteorological seasons make a lot more sense and clearly are what we should be using. Why aren’t we?
Do the meteorologists feel overlooked?
They say no.
Meteorological seasons are working perfectly well — for meteorologists, says Jeffrey Frame, an assistant professor in the Department of Atmospheric Sciences at the University of Illinois in Urbana-Champaign.
First, he says, meteorologists need to be able to keep records of temperatures, and it works best to do that by whole months.
“The meteorological community needs to note the average temperature in October, or how many days over 80 degrees there were in July,” he says. “That, versus from June 21 to July 21, say.”
Along the same lines, seasons also get grouped by temperature, he says. “We’ll have our warmest temperatures typically at the end of July. And that falls right in the middle of meteorological summer.”
Incidentally, that delay between tilting closer to the sun and the days actually beginning to feel warmer is called “meteorological lag,” when climate conditions play catch-up. Just so you know what to call it next March 21.
Human civilizations around the world have been using the sun, not months or temperatures, to chart seasons for thousands of years. Think of the Egyptians. Or of the pagans or whoever built Stonehenge to mark the planting seasons.
The notion of what feels like spring or summer is a bit of a Midwestern notion in the first place, says Eric Snodgrass, also a U. of I. professor.
The seasons are perceived differently in the western United States, he says. “It’s more wet season/dry season.”
That’s even more so in places such as Southeast Asia, where monsoon season is the important demarcation.
But Frame agrees that we midlatitude Midwesterners might like the meteorological model better.
“Sure, right now people are coming up with their pumpkin-spiced whatever it is,” he says. “That’s September. It feels like fall. Not summer.”
Doug George is the baiduhai’s theater editor.
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