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In Seattle there is just under two hours between the end and start of astronomical twilight during the days surrounding the summer solstice.
Quote:
Originally Posted by Superduy
I live on 49 degrees, not sure about this though, I never go to bed that late.. messes up sleep routine.
At places near that latitude, which are at the edge of where astronomical twilight is present at the darkest time at the solstice, doesn't the glow from urban lights in the large cities (Seattle, Vancouver etc.) drown out some of that the effect, right?
At places near that latitude, which are at the edge of where astronomical twilight is present at the darkest time at the solstice, doesn't the glow from urban lights in the large cities (Seattle, Vancouver etc.) drown out some of that the effect, right?
Not really... because it manifests as a faint glow on the northern horizon that you can see even with the street lights on... at least here. Also because we have mountains to the north of where I am, it could also help to make it easier to differentiate.
An interesting thread. I don't know much about this, but I can tell you that here in the Southern Hemisphere, places at higher latitudes than 48 S are almost all of them here in South America (Argentina and Chile). Cities like RÃo Gallegos (51 S), El Calafate (50 S), RÃo Grande (53 S), Ushuaia (54 S). I was in RÃo Gallegos and El Calafate once in late January, and to tell you the truth, when it was dark, it was dark. I didn't notice anything strange, apart from the fact that the sun sets very late! I also was in London in late July/early August, and the same happened. So, as someone suggested in this thread, to the non-astronimical eye, this is not noticeable.
An interesting thread. I don't know much about this, but I can tell you that here in the Southern Hemisphere, places at higher latitudes than 48 S are almost all of them here in South America (Argentina and Chile). Cities like RÃo Gallegos (51 S), El Calafate (50 S), RÃo Grande (53 S), Ushuaia (54 S). I was in RÃo Gallegos and El Calafate once in late January, and to tell you the truth, when it was dark, it was dark. I didn't notice anything strange, apart from the fact that the sun sets very late! I also was in London in late July/early August, and the same happened. So, as someone suggested in this thread, to the non-astronimical eye, this is not noticeable.
I think I remember reading that 55 latitude (N/S) was the rough line where one really starts to notice the astronimical seasonal change in terms of only twlight in summer and total darkness in winter.
An interesting thread. I don't know much about this, but I can tell you that here in the Southern Hemisphere, places at higher latitudes than 48 S are almost all of them here in South America (Argentina and Chile). Cities like RÃo Gallegos (51 S), El Calafate (50 S), RÃo Grande (53 S), Ushuaia (54 S). I was in RÃo Gallegos and El Calafate once in late January, and to tell you the truth, when it was dark, it was dark. I didn't notice anything strange, apart from the fact that the sun sets very late! I also was in London in late July/early August, and the same happened. So, as someone suggested in this thread, to the non-astronimical eye, this is not noticeable.
If you were around 50 latitude S/N about a month after the summer solstice, you wouldn't have seen the effect of the faint glow of astronomical twilight on the northern horizon. Here in Vancouver (49N), it only manifests itself for a couple of weeks or so either side of the solstice.
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I always wonder what life is like in places that far north. Like in Alaska or Scandinavia. What would nightlife be in a place like Anchorage or Tromso? Reminds me a bit of that film Insomnia with Al Pacino. A summer in an arctic or sub-arctic place is something I want to experience at least once.
With DST it only gets dark after 10 pm in Melbourne at the height of summer and that was weird enough.
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