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Great PaulVDV 2021-03-09 14:22

Hello Mariusz,
With great interest I read your note on the 'blue hour'.
Do you know why in some parts of the world it is very rare to see a blue hour? I remember when I was in Kerala, South India, I hardly ever saw the blue hour. In that part of the world the sun was setting quite early, that is at a time everyone was still outside and I certainly couldn't have missed it.
In my experience, this had nothing to do with artificial lighting but I never found the exact reason.
Wonderful photo of a part of Hamburg's skyline with the well illuminated tower next to the dark tower.
I like the inclusion of the lamppost on this bank of the river. Also the alternation of the dark contours of the balustrade with the light from the opposite side in between.
Best regards, Paul

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Old 03-09-2021, 09:41 PM
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mkamionka mkamionka is offline
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Hi Paul,
I did mention in my note that the existence or length of the blue hour depends on the geographical latitude. In the southern countries there is no dusk or dawn.
But I am not sure what is the physical explanation of it.
Did you find it out?
M
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Old 03-09-2021, 09:43 PM
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BTW
the artificial light must be in good balance with the natural light if not the photo is just not pretty. Blue hour in the nature is not exciting as in the well lit city.
Kind regards,
M
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Old 03-09-2021, 09:48 PM
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Nice article here:
https://en.wikipedia.org/wiki/Twilight
But I still don't see the reason for regional differences. I will read it with fresh mind tomorrow
M
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Old 03-09-2021, 09:51 PM
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This figure shows it well:
https://en.wikipedia.org/wiki/Twilig..._world_map.svg

It makes sense:
https://en.wikipedia.org/wiki/Twilig..._of_occurrence
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