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Sunrise, Sunsets and lattitude

by Cmunro
Tags: lattitude, sunrise, sunsets
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Jan27-07, 10:15 PM
P: 34
I'm not entirely sure which category this fits into, so feel free to move this around.

Ok - heres what I can't quite work out. How are sunrises affected by the lattitude and logitude of the destination?

If I move 1000km south of a destination, along the same longitude - will the time of sunrise be the same,slightly earlier or slightly later?

I know that 1000km West seems to give a much, much later sunrise but I'm not entirely sure why. Also 1000km north gives a slightly later sunrise, but again I don't know why.

I'll appreciate any insights,


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Jan28-07, 07:29 AM
P: 748
You have to be able to visualise what's going on. The earth orbits the sun, one orbit is what we call a year. The earth also spins about an axis which passes through the poles, one rotation equals one day, we are spinning from east to west.

Light from a single source cannot shine upon the whole surface of the earth at one single time, if you are in the east the sun might be directly above you, but someone 1000 km west would see the sun at an angle (note this is a special case because the sun is rarely actually directly above you. One way to visualise this is to think about the shadows that would be cast.

The latitude will also make a difference because the earth's spin axis is not perpendicular to the sun's rays. Hopefully someone will find a good link that explains this a lot better than I can!
Feb12-07, 12:22 PM
P: 1
Wait, do you go to the American School of the Hague? Are you Cathelijne?

If you don't then never mind, but I was just wondering because we got the exact same assignment

Feb12-07, 10:45 PM
P: 34
Sunrise, Sunsets and lattitude

I don't go there, nor am I her. But yeah, it fed into my IB standard level maths assignment. Anyway, I found a different way to calculate it without an extensive knowledge of how exactly it all worked (although I do see how it all works now).
jim mcnamara
Feb13-07, 02:29 PM
Sci Advisor
PF Gold
P: 1,382
Sunrise & sunset -- it's a lot messier than you think and the effect is not "evenly distributed" by latitude as you may think.

Read about the analemma here:
Download the "sungraph" app from the same site:

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