Naked Science Forum
General Science => General Science => Topic started by: alisongill on 08/05/2022 12:25:47
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Hello
I am working through some US government regulations that restrict certain industry operations to daylight hours. Because of the confusion regarding what constitutes "daylight" they have stated set hours after sunrise and prior to sunset that operations can go ahead.
This what they say:
(i) No pile driving may begin until at least one hour after (civil) sunrise.
(ii) No pile driving may begin within 1.5 hours of (civil) sunset.
So my question is why have they put the word civil in brackets? I understand about the different twilight zones of civil, nautical and astronomical. My understanding is that the civil dawn twilight zone occurs before sunrise – i.e. the end of the civil dawn twilight zone is sunrise.
So I am confused why they call it civil sunrise? Is there a nautical sunrise that is a different time to civil sunrise (I think not but maybe I am wrong). Surely there is only one sunrise time ?
Do I call out the government regulators and say that they have written this wrong? Or can someone explain why they would write this (civil) sunrise? Do they mean official sunrise time (if yes why put the word civil in there at all) or do they mean the beginning of the civil twilight zone which is earlier than sunrise?
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https://en.wikipedia.org/wiki/Dawn#Types_of_dawn
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thanks but that is not what i was asking, I know what civil twilight zones are . My question is why are these government agencies using the term civil sunrise
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thanks but that is not what i was asking, I know what civil twilight zones are . My question is why are these government agencies using the term civil sunrise
Because they want to distinguish it from the others.
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Others? What do you mean by others? How many sunrises are there in one day?
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How many sunrises are there in one day?
Three.
Astronomical dawn
Nautical dawn
Civil dawn..
Did you not read the wiki page?