DOWNTOWN — Some say fall started Saturday. Others insist it’s not coming until Sept. 23.
As it turns out, everyone’s wrong … and everyone’s right. It just depends on what you’re talking about.
In Chicago, there are four generally recognized seasons: winter, spring, summer and fall (if you’re not counting construction season, hey-oh). But when those seasons end and begin depends on if you’re talking about meteorological seasons or astronomical seasons. And, as Block Club has learned through its weather stories, people love to debate which one is right.
“In reality, neither one is more right than the other,” said Michelle Nichols, the director of public observing at the Adler Planetarium. “It just depends on what you need to use them for.”
The National Weather Service — and meteorologists in general — use meteorological seasons, which divide the year into four three-month periods that end and begin on the same dates every year (unless there’s a leap year). That helps experts more easily compare temperatures, rain and other data from one year to another:
- Spring: March 1-May 31
- Summer: June 1-Aug. 31
- Fall: Sept. 1-Nov. 30
- Winter: Dec. 1-Feb. 28/29
“We do it for climate purposes. What it does is it allows us to keep data consistent every season,” said Kevin Donofrio, a meteorologist with the National Weather Service.
Astronomical seasons also split the year into quarters, but the start and end dates of those seasons vary each year depending on when the spring and fall equinoxes and summer and winter solstices occur.
“Astronomical seasons are defined by, essentially, the earth’s position around the sun, which then has an effect on where we see the sun in the sky,” Nichols said.
Here’s how the astronomical seasons will work out next year:
- Spring: March 19-June 19
- Summer: June 20-Sept. 21
- Fall: Sept. 22-Dec. 20
- Winter: Dec. 21-March 21, 2021
The varying start and end dates of astronomical seasons means the length of those seasons varies year to year. So while astronomical seasons make sense for Nichols’ line of work, using them would make it harder for weather experts to track and compare seasonal data.
Essentially, both ways of looking at seasons are right. They just have different uses.
Still, people continue to debate which is “right” — and the subject becomes especially touchy as Chicagoans try to cling onto the warm summer before another winter hits.
Nichols, as an expert in astronomy with the Adler for 24 years, tends to thinks of the seasons in terms of their astronomical dates.
People are “so conditioned where we think of the day of spring as March 20th, 21st, somewhere around there,” Nichols said. “We tend to think of that because that’s what the regular calendar might say.”
But Donofrio, as a weatherman, says his long years of training mean he thinks of the seasons in terms of their meteorological dates even when off the clock.
“It all just depends on where you live, what you think,” Donofrio said. “Maybe up in Minnesota, Wisconsin, it probably feels like autumn [already]. … Whereas if you’re down in Tennessee or Arkansas, you may not feel the same way.”
Nichols said she personally hopes people don’t debate which way of defining the seasons is “right” and instead focus on how both definition have their own uses.
“… People think you have to have a winner for a debate and you don’t. You present both sides and, in this case, there’s no one that rises to the top,” Nichols said. “It just depends on what you need it for, what you need the information for and what you’re using it for.
“I kind of hope the debate stops with, ‘Here’s this side, here’s that side.'”
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