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Vitali
167385.  Wed Apr 18, 2007 11:35 am Reply with quote

Q: Where in the world does dawn happen at midday?
or:
Where in the world does the sun set at midnight?

F: Around North/South pole

A: In Mount Athos, where modrn time does not exist, and each monastery has its own! Clocks in some monasteries are set to midday at dawn; in others - they are set to midnight at sunset. This makes fixing any kind of appointment on the Holy Mountain a pretty hopeless business, but this doesn't seem to bother the monks whose only "appointments" are with God.

Own research

 
suze
167398.  Wed Apr 18, 2007 11:58 am Reply with quote

You might need to check out China. They use the same time zone throughout China - UTC +8, which is appropriate to Beijing but is used nationwide. Therefore, the western extremities of China are subject to time three hours later than geography would suggest. Could this lead to dawn at midday or sunset at midnight at certain times of year?

 
Jenny
167425.  Wed Apr 18, 2007 12:42 pm Reply with quote

What about countries way up in the Arctic circle? Wouldn't they sometimes have dawn at midday or sunset at midnight at certain times of year?

 
suze
167428.  Wed Apr 18, 2007 12:46 pm Reply with quote

My first thought is "no". For sure, those places have days on which the sun does not rise, and days on which it does not set. But if it's going to rise at all, it's done so before midday - and similarly at the other end of the day.

That's a first thought though, and since I'm on vacation I'm trying to avoid too much thinking. I'll do a bit of digging after dinner ...

 
dr.bob
167606.  Thu Apr 19, 2007 4:00 am Reply with quote

Midday is when the sun's at its highest in the sky, right? Now, on those days when the endless night is just coming to an end, you'd just get a tiny bit of sunlight as it peeps over the horizon. I'd've thought this would happen when the sun was at its highest, i.e. at midday. So, when the days are very short (like a few minutes or so) you'd get a sunrise almost immediately followed by a sunset, and both of these should happen around midday.

The converse logic applies when the endless day is coming to an end. A sunset almost immediately followed by a sunrise, around about midnight.

In other words, I think Jenny's on to something here, though I'm neither a meteorologist nor a Scandinavian, so I could be talking rubbish.

 
eggshaped
167608.  Thu Apr 19, 2007 4:05 am Reply with quote

I agree with Dr B on this one. I think a forfeit for North or South Pole is a bit unfair. At least unless we can clearly and consisely explain why it is incorrect.

 
suze
167626.  Thu Apr 19, 2007 5:03 am Reply with quote

Beat me to it, dr.b and egg.

The bit I wasn't sure about was whether noon actually is that time at which the sun is highest. Having looked up references to "solar noon", "the equation of time", and so on the answer would appear to be that it probably isn't. But at some points on the Earth it will be, and the explanation isn't really very interesting, so for these purposes we may take it that it is.

So yes, there will be days on which the sun makes a brief appearance either side of noon - and on which it makes a brief disappearance either side of midnight. What there won't be in the polar regions is days of the kind Vitali actually had in mind - where sun rise is at noon, and the sun then sticks around a while.

These will happen at Mount Athos as explained, but could it also happen in China? Lacking the knowledge or data to explore this properly, I'm not entirely sure.

However, a quick look at a map shows the westernmost part of China to be at about the same latitude as Barcelona. At the start of July, sunrise in Barcelona is at 0622 and sunset at 2129. Shifting these by three hours, we get sunrise at 0922 and sunset at 0029 - so I reckon it's completely possible that western China gets a sunset at or around midnight in the height of summer.

(Data from here.)

 
dr.bob
167657.  Thu Apr 19, 2007 5:49 am Reply with quote

suze wrote:
The bit I wasn't sure about was whether noon actually is that time at which the sun is highest. Having looked up references to "solar noon", "the equation of time", and so on the answer would appear to be that it probably isn't. But at some points on the Earth it will be, and the explanation isn't really very interesting, so for these purposes we may take it that it is.


To be honest, I don't think we need to take it that it is.

Imagine that, for whatever reason, the sun is at its highest in the sky at 12:30. That means that, for the circumstance we're talking about where an endless night is coming to an end (as it were), the sunrise/sunset would be either side of 12:30. Logically, there would be some point in the year where the sun rose at 12:00 and set at 1:00. That's even better since it's more a case of the sun rising, sticking around a while (for some value of "a while"), and then setting.

suze wrote:
At the start of July, sunrise in Barcelona is at 0622 and sunset at 2129. Shifting these by three hours, we get sunrise at 0922 and sunset at 0029 - so I reckon it's completely possible that western China gets a sunset at or around midnight in the height of summer.


Superb. I'd've never have thought of that! Now we just need a field trip to China to verify it :)

Hope you're enjoying the vacation, BTW.

 
suze
167788.  Thu Apr 19, 2007 8:03 am Reply with quote

dr.bob wrote:
Now we just need a field trip to China to verify it :)


If it turns out that three people in an almost abandoned village in that region speak a language otherwise unknown to me, I could probably even get funding for that!

Quote:
Hope you're enjoying the vacation, BTW.


Oh I am! I've been a bad suze today though, and brought my laptop with me on our day's excursion. I decline to state the actual reason for this, on the grounds that it would at once mark me as a sad git. (OK, it's to do with the word game on the QI Games forum - I'm in the lead going into the final furlong, and I've gotten a bit paranoid about being caught up. Yup, sad git is about right.)

 
dr.bob
167794.  Thu Apr 19, 2007 8:18 am Reply with quote

suze wrote:
If it turns out that three people in an almost abandoned village in that region speak a language otherwise unknown to me, I could probably even get funding for that!


OK, so now all we need is three volunteers to go and live in a remote part of western china and start speaking a made-up language so that suze can get funding to go out there and check the times of the sunset at the same time.

Errrmmmm, yeah, that makes sense to me :)

suze wrote:
Oh I am! I've been a bad suze today though, and brought my laptop with me on our day's excursion. I decline to state the actual reason for this, on the grounds that it would at once mark me as a sad git.


Surely not!

suze wrote:
(OK, it's to do with the word game on the QI Games forum - I'm in the lead going into the final furlong, and I've gotten a bit paranoid about being caught up. Yup, sad git is about right.)


You sad git!

 

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