When seasons begin — revistited

By Jack Williams ©2015

Q: Hello Jack. I was wondering if anyone ever turned in an answer on your “official seasons” proposal from last summer. I am doing my senior research project on the seasons, and would like to know what you found out. Thank you for your time.

Justin, Redwood Falls, MN

Where it's light and dark on earth at 11:30 a.m. ET on April 1.

A: The question refers to an article I published last June, “Summer begins Sunday! Really?”

After saying that I’ve never found any evidence that the solstices and equinoxes are really “official” beginnings of the seasons, I wrote:

“I’m so sure that there’s nothing “official” about these dates being the beginning of seasons that I’m making an offer: I will send (postage paid) a signed copy of my new AMS Weather Book to the first person to send me information about a law adopted by the U.S. Congress and signed by the President, or even a Presidential proclamation, making the solstices the “official” beginning of summer or winter.”

No one rose to the challenge, and the offer still stands.

For your research project, I think the best place to start is Keith C. Heidorn’s  The Wheel of the Year on his Weather Doctor Web site. My June 2009 piece has more on what he has to say.

For example he discusses cross-quarter days–Groundhog Day is an example.This is a good introduction to the things that ancient people learned from closely watching the sky during the year. Knowing the position of the sun helped early farmers tell the difference between a winter thaw and the real beginning of spring and led to the invention of calendars.

Where it's light and dark on earth at 11:30 a.m. ET on June 21

The images on this page are from the U.S. Naval Observatory’s Day and Night Across the Earth Web page.

They show what you would see if you could look down from space on the North Pole at the times and dates shown.

Since both views are of the Northern Hemisphere, more of the earth is illuminated around the time of the summer solstice in June than in April, a couple of weeks after the spring equinox.

In other words, Northern Hemisphere days are longer in June than in April.

Knowing this kind of stuff is part of understanding how the position of the sun in the sky–as seen from the earth–explains not only the seasons but why summer days are longer than winter days.

Chapter 2 of the AMS Weather Book explains all of this with the help of graphics.

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