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Sunlight surprise

DST over now, right. So I thought to look at the sun times:

Actual Time 6:19 AM EST 4:36 PM EST

Aaaagh sunset at 4:30??? Why does this keep surprising me? I remember being shocked at 4pm times last winter, before I fled south.

Then it occurred to me that that implied a 9 hour day, which seemed pretty short. So I look at sunrise. Huh: it's 5.5 hours to noon, but only 4.5 hours after that. And to confirm:

Length of Day 10h 17m

So solar zenith comes early to Boston, around 11:30, in fact. Or 11:28, even.

Combined with my discovery a couple years ago that Chile cheats on its time zone, with summer zenith at 1:45pm (or so I thought; this says only 1:29) no wonder my trips south seem weird. Not just much longer (and warmer) days but zenith shifts forward by two full hours, with Boston revealed to be early.

Oh wait, I wasn't wrong: skipping forward on that site, La Serena's zenith in late December will be 1:47 (not sure why it shifts like that). Boston has the same advancement though (duh?), so it's still a two hour difference.

I have an anti-DST bias that noon should equal zenith, but if zenith is going to be at :30, then it might as well be at 12:30 rather than 11:30...

See the comment count unavailable DW comments at http://mindstalk.dreamwidth.org/407154.html#comments



( 4 comments — Leave a comment )
Nov. 2nd, 2014 09:53 pm (UTC)
Noon-at-zenith caused the proliferation of local times that time zones were introduced to reform. Chile's peculiar autarky in this area is not the only instance, but seems to be the most pointless.

It's also worth mentioning that seasonal changes in daylight result in a sine wave variation in total sunlight per day, as do latening sunrise and sunset times, but both follow a curved progression when the are becoming progressively earlier in their turn, as the charts produced by this app will illustrate: http://ptaff.ca/soleil/?lang=en_CA
Nov. 2nd, 2014 10:12 pm (UTC)
Huh, I thought that post had noted Chile's not the only one. Looking at the map, you can see Argentina is also out of line, as is Spain. I'd thought it was a shared taste for sunlit evenings and late night lifestyles, but this says Franco did it in solidarity with Hitler. Don't know about Chile and Argentina, though one page suggests Chilean roots in saving electricity after WWII.

And if you include a link, just wait for me to approve the comment.

Edited at 2014-11-02 10:13 pm (UTC)
Nov. 3rd, 2014 04:49 am (UTC)
Well, it's saying that it's marked as spam, not that it's being held for moderation as at other blogs.

I see I also nodded on my post; early-ing events seem to follow a more linear progression. I first noticed this in a stargazing guide where the night hours formed an odd hourglass shape.
Nov. 3rd, 2014 06:36 am (UTC)
I don't have fine control of the policies. But suspected spam gets held.
( 4 comments — Leave a comment )


Damien Sullivan

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