Unusual daytime cycles

[MirceaKitsune]

I live somewhere in Europe. Like all people who live here or in America at least, we're used to a classic day time cycle; The sun rises from one location, travels in an arch across the sky, then sets in another location... same story for the moon. At the poles of course, things are really different: A day and a night typically last for over a month. Since that's around the center of the Earth's rotation axis, it makes perfect sense too, considering Earth's spin barely reposition those locations in relation to the sun unlike living in areas where the spin has greater effect.

 

But I was wondering one thing: What happens in between those two locations? If around the planet's "belt" the sun rises and sets every 24 hours due to spin, while at the "ends" it rises and sets on a monthly basis due to position in orbit and / or tilt, it sounds that somewhere along the way there are places where we should see quite some unusual sun movement. Maybe even the sun slightly wobbling back and forth.

 

One case that comes to mind: Somewhere between the outer edge of the world (in the spin's direction) and one of the poles, we should have one of two things: A place where a day lasts for say a week rather than either 24 hours or more than 1 month, or a place where you can see the sun only shining in one direction during the 24 hour day while other areas are only lit during the monthly day. The second feels like the correct option... since the Earth's spin is after all the same everywhere, so there should only be a virtual line where sunlight cuts off regardless of the Earth's rotation around the spin axis. So in practice, shouldn't this mean that somewhere out there, there's a place where if you climb on top of a mountain, you can see daytime to your left and nighttime to your right during certain hours and days?

 

Where and what are the most unusual day cycles on Earth, in case there are any? Are there any pictures or videos of them that you can share also?

[Acme]

I live somewhere in Europe. Like all people who live here or in America at least, we're used to a classic day time cycle; The sun rises from one location, travels in an arch across the sky, then sets in another location... same story for the moon. At the poles of course, things are really different: A day and a night typically last for over a month. Since that's around the center of the Earth's rotation axis, it makes perfect sense too, considering Earth's spin barely reposition those locations in relation to the sun unlike living in areas where the spin has greater effect.

At the poles they experience ~ 6 months daylight and 6 months night. Here's a link describing an experiment to see how this works. >> Six Month Day, Night at Poles You can use the same setup to look for effects at other latitudes.

 

But I was wondering one thing: What happens in between those two locations? If around the planet's "belt" the sun rises and sets every 24 hours due to spin, while at the "ends" it rises and sets on a monthly basis due to position in orbit and / or tilt, it sounds that somewhere along the way there are places where we should see quite some unusual sun movement. Maybe even the sun slightly wobbling back and forth.

By photographing the Sun at Zenith everyday and then putting the photos together you will see this "wobbling" as a figure-eight form called an analemma. The exact proportions and orientation of an analemma are determined by your location. There are diagrams at the link in the preceding sentence.

 

One case that comes to mind: Somewhere between the outer edge of the world (in the spin's direction) and one of the poles, we should have one of two things: A place where a day lasts for say a week rather than either 24 hours or more than 1 month, or a place where you can see the sun only shining in one direction during the 24 hour day while other areas are only lit during the monthly day. The second feels like the correct option... since the Earth's spin is after all the same everywhere, so there should only be a virtual line where sunlight cuts off regardless of the Earth's rotation around the spin axis.

Try the experiment I linked to and see if you can answer the question.

 

So in practice, shouldn't this mean that somewhere out there, there's a place where if you climb on top of a mountain, you can see daytime to your left and nighttime to your right during certain hours and days?

 

The day/night line is called a 'terminator' and I'm not sure you can see it from 'tall' mountains. You can see it from aircraft if you happen to be at the right time. You can watch it right now every 45 minutes from the new HD cams mounted to the ISS. Here: >> ISS HD Earth Viewing Experiment

 

 

Where and what are the most unusual day cycles on Earth, in case there are any? Are there any pictures or videos of them that you can share also?

Here's a Google link to analemma photos: >> https://images.search.yahoo.com/search/images?p=analemma&fr=yfp-t-901-s&fr2=piv-web&ri=7&tab=organic&ri=2

[MirceaKitsune]

Thank you, that's very useful and complete. Also many terms I didn't know. And yes, that was indeed 6 months not "somewhat over 1"... not sure why I remembered a slightly lower number.

[swansont]

There are a number of images on the web of a cumulative exposure with a pinhole camera over many months, which shows the sun's track and how it changes

 

http://benfry.com/writing/archives/652

http://laurensowter-ed1-pinholecamera.blogspot.com/

http://www.wjla.com/blogs/weather/2011/06/weird-solargraphs-show-entire-spring-s-worth-of-sun-photo--11461.html