Daylight Savings Day.
Nature is making the evenings longer all by itself.
We are just above the 42 degrees north latitude. We are on about the same parallel as Chicago (42), Boston (42), New York City (41),Toronto (43), French Riviera (42), Tuscany (43), Beijing (40). All places along this latitude experience about the same length of day, although the climates are very different.
Summer days at this latitude are 6 hours and 12 minutes longer on the summer solstice than they are at the winter solstice. There are 15 hours, 20 minutes of daylight on June 21 versus only 9 hours and 8 minutes on December 21. That means that over that 182 days there is a gain or loss of 372 minutes-- an average of 2 minutes and 4 seconds a day.
What may not be intuitive is that this gain or loss does not take place evenly over that period. The month of March begins with a day length of 11 hours, 18 minutes. March ends with a day of 12 hours, 44 minutes, a gain of 96 minutes in 31 days. That is 3 minutes and 10 seconds a day--a very noticeable difference, especially coming at dinnertime or in an evening commute.
People may have a sense that all of December is unchanging in its darkness, or that early summer is endless in its long, long evenings. That is not an illusion. In the 30 days leading up to the December solstice the days are short and stay short, with little change in the length of day. On November 21 the day is 9 hours, 38 minutes. On December 21 it is 9 hours, 8 minutes, a change of only 40 seconds a day. The period where the day length is in the 9-hour range goes from November 10 through January 31, which is 82 straight days of early darkness. A similar period of little-changing daylight happens in the summer, with its two-plus months of 15-hour days.
What we experience is a long period of unchanging days at the solstices, and then a period of rapid changes around the equinoxes. It isn't your imagination and the the longer evenings are not just from switching the clocks. The days really are getting noticeably longer, and it is happening right now.
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8 comments:
Oh no! All this extra daylight is liable to make people feel more woke. The next thing you know, they'll start believing facts. Quick, shut the blinds and turn on Fox!
2 years ago Florida voted to keep Daylight Savings Time permanently. However, only Congress can approve it. That hasn’t happened yet. In fact Congress hasn’t even discussed it. Living in Florida, I would love it.
Daylight makes you feel alive. Night makes you feel sleepy. I love the sun. In fact, I worship the sun. At least I can see it.
Yesterday's blog was a hot mess. A suggestion: As a courtesy to ladies, gentlemen and younger readers, perhaps it would be helpful (and kind) to add a "reader discretion advised" warning at the beginning of blogs with graphic sexual or violent content. This is fairly common in the media, even on social media.
If readers are forewarned, they should not feel ambushed and dispected. They can make the decision to read it, skip it or read it another time.
Concerning this blog, probably almost everyone who is not in a coma is aware that that days gets longer and shorter as the seasons change. We really are not as stupid and oblivious as you seem to think, even if we didn't attend an Ivy League school and are not engaged in agriculture.
I don't consider it obvious that the Chang in length of days are tiny at the solstices, and huge at the equinoxes. A college classmate who is more familiar with higher math than I am gave an explanation: Sandford Borins wrote me:
Peter, good post.
What you’re describing is a logistics curve, which is obviously nonlinear.(I.e. hours of day light on the y axis, date of the x axis).
It is widely used for example in studies of the diffusion of innovation.
Can’t think of other uses off the top of my heard, but there are many.
Best,
SB
I would love to hear from other readers, and perhaps the anonymous commenter, the math involved in the changing angles of the radii of a sphere as it turns. That would offer some healthy rigor to the post. It is beyond my math skills, personally, and to me is is far from obvious or simplistic.
Peter Sage
Disrespected (typo)
Actually, it is pretty obvious when the days get longer and shorter, especially the further you are from the equator, but the mathematics of it are another story. I suppose that’s the difference between a scientist and a lay person.
As for yesterday’s post, it was titled “Hush Money to Stormy Daniels.” If that wasn’t enough warning that it dealt with sleaze, someone isn’t paying attention.
Living in Alaska for 40 years made me very aware of the change. Around December 21 st the next day is 3 seconds longer. Around March 21 st the change is 6 minutes and something. It’s hard not to notice when a 6 minute change happens daily. I always mark January 26 th as the sun returns to what used to be called Barrow, Alaska. It marked for me the end of the heart of winter.
True. The public is more stupid and oblivious than most people think.
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