Yawn! That’s not my reaction to the title, but to the sleepiness that comes from giving up Lent, eating chocolate (provided at half price by Safeway on Easter Monday), and sleeping in after a sugar rush. Easter, is a Spring holiday – not by chance, but by design: Spring officially starts on the Spring equinox, and Easter falls on the first Sunday after the first full moon after the Spring equinox (unless bla bla). Since there is one full moon in every 29-something days, you are guaranteed to see Easter happen soon after the official start of Spring.

Yet, because I am a nerd, the first thing that comes to my mind is not Christ, the Lord and Savior returning, it’s not bunnies and chocolate, and it’s not even the painful reminder that the snowboarding season is almost over. In fact, the first thing that comes to my mind about every three months at the change of seasons is, “but the season has long started!”

Yes, all of March is relatively mild, despite the fact the first two thirds are officially winter. It’s the exact same thing for all seasons: June is already hot as all get-go, except maybe in San Francisco and Fairbanks, AK. September is my favorite month, and the hottest in San Francisco – but it’s the hottest there precisely because temperatures dip to its East. And finally, the cruelest joke of all, Christmas is close to the coldest day of the year, but it’s just the beginning of winter.

What’s the deal? Why do we assign some random point about a third of the way into the season as its beginning?

Let’s take the Winter solstice, traditionally falling around the 21st of December. It is the day with the shortest daylight duration. Before it the days were longer, and after it they will be shorter. Since our Earth relies on imported heat from the sun, the shortest daylight should coincide with the least heat. The coldest day of the year should be the Winter solstice!

Things aren’t that quick, since it takes the atmosphere some time to adapt to change, sort of like it’s been caught doing the naughties with the sun and needs to straighten out her dress. But, in fact, at least in Denver, the coldest day of the year is December, 26th, not even a week after the solstice. It is in fact very odd that we consider what should be the exact middle of winter, the beginning. Even when taking into account heat inertia, it makes very little sense to consider the solstice the beginning of the season instead of its middle.

But it’s convenient. The dates of equinoxes and solstices are constant, we need a day to start the seasons, might as well pick something that is somewhat related to them (even if the day picked should be the middle of the season by logic). Generally, it feels like the seasons should align more with the months (all of December, January, and February in winter, all of March, April, and May in spring, etc.), but who cares?

Well, your resident nerd cares. I went and decided I was going to compute when the seasons really begin and how long they really last!

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