A while back there was a post where someone referenced the Digital Time that was proposed by the French Revolution. Well, arguments about our calendar are really useless.

Or are they.

Your calendar: Summer (the season) begins on June 21st.

Status: You’re doing it wrong.

I can’t believe the resistance that I get about this topic. It seems pretty simple to me. Why is June 22nd a summer day but June 20th belongs to spring? Chasing that question down led me to some surprising results.

If you plot the deviation of daylight hours over the year it looks like a sine wave.

But this looks weird. The days of summer don’t start until the longest day of the year?

And, I had always wondered about Ground Hog Day. What was its significance? Wasn’t the first day of spring always fixed at 6 weeks after GHD? Spring is delayed until March 21st? Duh!

It turns out that the dates of the seasons are fairly arbitrary.
In fact, I cannot find where the dates were set to the current observation1. The “usual” observance doesn’t seem to have much of a tradition behind it other than it being the system in use.

So, what would be a logical definition of the seasons? It seems to me that the best layout would be based upon the duration of the solar day. To me, the Summer Solstice would not be the beginning of summer but rather the midpoint.

Well, what do you know; this has been the standard recogntion for hundreds of years!

Suddenly the Ground Hog Day tradition makes sense. Spring starts on Feb 2 (halfway between the Solstice and the Equinox) but rodent-shadow “Spring” starts on the Equinox instead as an abberation. May Day never made sense to me (other than the Soviet orgasm) but now it was simple: It’s the first day of Summer. Hallowe’en, the first day of Winter. Autumn begins on August 1st.

The earth has changed orientation over time and the alignment of the seasons has changed as well. If we were to do a strict reckoning then we would use the last graph, summer starting about May 6th and the other seasons following every 91.25 days. To choose the traditional dates (May 1st, August 1st, October 31st, February 2nd) seems to me to be a reasonable compromise, bringing matters back to traditional observations while being closer to the solar midpoints.

I’m trying to keep weather out of this discussion, but for my region, November is a winter month. I could argue spring and fall, but May is a summer month here, as well. The USWS is off of my schedule slightly as they say that summer begins on June 1st (all others follow). It seems to me to be a rather arbitrary choice based more upon weather than anything else. It is their setpoint, not mine2. But basing the reckoning of seasons upon the weather makes little sense in places like Hawai’i. My friend spent some time there and mentioned that there is no weather segment on the local news. Every day had basically the same high and low temperatures year around. If there was something else (“Typhoon On The Way”) then it was news, not weather.

I can’t help but to be an engineer whose job is to “fix things.” Here’s a fix for something that you never knew was broken.

Now get off my lawn.

1. I haven’t looked very hard

2. They are the “Weather Service” after all