Re: Length of magic light dependant on latitude...


"Pete Bridgwood" <pete@xxxxxxxxxxxxxxxxxx> wrote in message
news:4537c11d$0$8736$ed2619ec@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
| Hi,
|
| Don't know if anyone can help here but here goes:
|
| I am a photographer living in the midlands in the UK. I recently visited
| Scotland (Skye) in March and was surprised at how much longer the
beautiful
| colours around sunset and sunrise (magic light) were visible in the sky
when
| in Scotland compared to further south. It seems that in Nottingham,
whenever
| there is a nice pink sky, it only ever lasts for maybe 10 minutes. In Skye
| the sky was a wash of colour for what seemed like 30 minutes or more.
|
| I have looked at length of sunrise - this is slightly longer in the north
at
| some times in the year (only by about 5 mins though).
|
| I have checked the times of civil twilight and again cannot find an
| explanation for this phenomenon.
|
| Has anyone got an explanation that I could understand?
|
| Cheers
| Pete

As you realize, summer daylight lasts longer than winter daylight,
and the further north you are the greater the difference. Once
you reach the North Pole the sun appears to travel all around
360 degrees on Midsummer's day, never setting, but only rises
23.5 degrees because of the tilt of Earth, falling to touch
the horizon.
Now of course twilight is seen after the sun has set, so if you
in the far north the sun remains just below the horizon.
Daylight on March 21st is 12 hours long with 12 hours of "night",
but in the far north that night is nearly all twilight.
Since you are a photographer, find a hill in the midlands, take a tent
and a sleeping bag, set your camera on a tripod and photograph
the sun at dawn (with appropriate filters).
Rotate the camera 15 degrees and wait 1 hour.
Take another photograph toward the sun. Rotate again by 15 degrees
and wait another hour, repeat for 24 hours. You'll then have a 360
degree panorama of 24 images and should discover the path the
sun takes in both daylight when you can see it and at night when
you cannot, a sine wave.
http://users.uma.maine.edu/faculty/rsm/slides/chap4/f4-3a.gif.

You can then publish your panorama on the web :-)

Androcles






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