Sunrise, Sunset, and Twilight! What are your city's times for today? Part 2 (september, latitudes)
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It looks like we reach our 8:00pm sunset on August 26 and by August 31 we are at 7:50pm for sunset, and it gets earlier and earlier into September. We don't reach a 7:00am sunrise until September 25, so over a solid month still of sunrises in 6:00 hour. By the time the clocks "fall back" on November 1, our sunrises are near 8:00am, but switch to 7:00am, and back to near 8:00am on December 21!
We're down 54 minutes of daylight since the solstice. Interesting that by this point in winter we've already gained 58 minutes of daylight vs only losing 54 minutes in the summer since the solstice. It's only a few minutes difference but it shows that we gain daylight faster in the winter than we lose it in the summer.
Also, days get longer in the summer than nights do in the winter. On Feb 1st here we have 14hrs 08min of darkness vs 14hrs 34min of daylight on Aug 1. That's a 26 minute difference!
For the Solstices, the longest day here is 15hrs 28min vs 15hrs 06min for the longest night. That's a 22 minute difference.
The period of darkness and its changes about the solstices are symmetric, but are mirror imaged - that is, in late spring, the earlier sunrises occur first, the latest sunsets lag - extending to around July first, while sunrises are already going later for weeks.
Conversely, in late fall, it's the opposite. The earliest sunsets are on/around December 8th - already gone 3 - 4 minutes later by Dec 21st. Latest sunrises come after Christmas.
It has something to do with the geometry of an ellipse, I think.
The period of darkness and its changes about the solstices are symmetric, but are mirror imaged - that is, in late spring, the earlier sunrises occur first, the latest sunsets lag - extending to around July first, while sunrises are already going later for weeks.
Conversely, in late fall, it's the opposite. The earliest sunsets are on/around December 8th - already gone 3 - 4 minutes later by Dec 21st. Latest sunrises come after Christmas.
It has something to do with the geometry of an ellipse, I think.
Yeah but there are differences between Winter and Summer in that regard. Summer has more daylight than darkness in winter and it takes a bit longer to lose daylight in Summer than to gain it back Winter.
Plus with twilight, the shortest day here has 9 hours of daylight but 10 hours of visible light vs 15.5 hours of daylight on June 21st with 16.5 hours of visible light thanks to twilight. Light dominates more than darkness around here.
Yeah but there are differences between Winter and Summer in that regard. Summer has more daylight than darkness in winter and it takes a bit longer to lose daylight in Summer than to gain it back Winter.
Plus with twilight, the shortest day here has 9 hours of daylight but 10 hours of visible light vs 15.5 hours of daylight on June 21st with 16.5 hours of visible light thanks to twilight. Light dominates more than darkness around here.
Length of twilight ALWAYS depends on latitude. At high latitudes the sun rises and sets at more of an angle and therefore twilight persists longer after sunset. Even in December, twilight persists longer at latitude 45 than it does at latitude 20, both summer and winter. At latitude 68 twilight still occurs in late December - for several hours in fact, even if the sun never makes it over the horizon.
Not sure what you mean by more light in summer than darkness in winter. I'll have to think about that one.
The period of darkness and its changes about the solstices are symmetric, but are mirror imaged - that is, in late spring, the earlier sunrises occur first, the latest sunsets lag - extending to around July first, while sunrises are already going later for weeks.
Conversely, in late fall, it's the opposite. The earliest sunsets are on/around December 8th - already gone 3 - 4 minutes later by Dec 21st. Latest sunrises come after Christmas.
It has something to do with the geometry of an ellipse, I think.
The date "offset" of earliest sunrise/latest sunset dates from the June (summer for NH) solstice is also smaller than the date offset of earliest sunset/latest sunrise dates from the December (winter for NH) solstice... Due to longer day length (from solar noon to next solar noon)
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