/ Modified dec 20, 2022 3:11 p.m.

Winter solstice: Why isn't the shortest day of the year in the deepest part of winter?

It may be the day with the fewest hours of sunshine for the global north, but there is another source of heat to consider.

Buzz Winter Solstice Rare desert winter snow on saguaro cactus in the Catalina Mountains.
Pete Gregoire, NOAA Photo Library

If you are in the northern hemisphere, then today will seem pretty short.

To use the Tucson area as an example, apparent sunrise is expected after 7:28 am and sunset coming at 5:25 pm, the winter solstice is the day at which the north pole is tilted the most away from the sun, meaning the sun is at its lowest point on the horizon for those north of the equator.

But why isn't the day that we get the least amount of warming sunshine the coldest point of the winter rather than the start of it?

"We're still cooling down," Aaron Hardin, a meteorologist with the National Weather Service office in Tucson, said. "Even though after the winter solstice we're going to start to receive more solar energy, it's still not a whole lot so we're still going to cool off."

He said that the ground below us is radiating heat.

To help explain, Hardin used an analogy that puts things on a shorter timeframe and also talks about the inverse.

"The hottest temperature isn't usually at solar noon when the sun is the highest in the sky, which can be 1:00-2:00 pm. Sometimes the warmest temperature is at 3:00-4:00 pm. It's the same thing with the seasons. There's just a slight lag."

And while on traditional calendars, this is the start of winter. That is not so for meteorologists. Hardin said that meteorological winter makes up the entirety of December, January and February.

By posting comments, you agree to our
AZPM encourages comments, but comments that contain profanity, unrelated information, threats, libel, defamatory statements, obscenities, pornography or that violate the law are not allowed. Comments that promote commercial products or services are not allowed. Comments in violation of this policy will be removed. Continued posting of comments that violate this policy will result in the commenter being banned from the site.

By submitting your comments, you hereby give AZPM the right to post your comments and potentially use them in any other form of media operated by this institution.
AZPM is a service of the University of Arizona and our broadcast stations are licensed to the Arizona Board of Regents who hold the trademarks for Arizona Public Media and AZPM. We respectfully acknowledge the University of Arizona is on the land and territories of Indigenous peoples.
The University of Arizona