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Calculating Winter sunrise/sunset times behind hill?

 
Tylwyth Teg
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Hi guys

Is there a (simple-ish) way of calculating how much sunshine a place will get in the depths of Winter if all I know is what time the sun disappears behind the hill today?

I've looked online but can't find anything...

Latitude is 52 degrees North and yesterday the sun disappeared 2 hours before sunset so am concerned that with 7 weeks still to go til the shortest day this may be a cold site in Winter...Brrrr!
 
Jonathan Byron
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To get an exact answer, you would need trigonometry and the angle between the ground and the top of the hill.

You can be confident that you will get at least 2 hours less sun on the shortest day in winter than is predicted for your latitude. You might lose even more - the hill could block all direct light for part of the year if it is tall enough.

If there is a hill to the east, that would also cut off sun in the morning. 

Here are some of the basic formulas for sunrise/sunset calcs, they need to be adjusted for your case. A hill or building effectively bumps up your latitude.

http://williams.best.vwh.net/sunrise_sunset_algorithm.htm


 
Saybian Morgan
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Location: Lower Mainland British Columbia Canada Zone 8a/ Manchester Jamaica
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This is the greatest calculator I have ever seen!

I went back to a photo 3 years ago and matched the shadows with it's calculations of where the sun was on that very day at that very hour and it was acurate as hell.  I'll be using this tool as a designer forever I just hope they never take it offline.

Google Maps plus a global any location sun calculator for any day in the year thought time, what more could a designer ask for.
www.suncalc.net
 
Eric Thompson
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Location: Bothell, WA - USA
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For rough planning, you can use Google Earth which will let you overlay shadows by time of day throughout the year.  The altitude data is pretty coarse, but the visual over the sattelite view is quite useful to get a feel for it! 
 
David Miller
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Location: Harrisonburg, VA
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SaybianTv wrote:
I went back to a photo 3 years ago and matched the shadows with it's calculations of where the sun was on that very day at that very hour and it was acurate as hell.  I'll be using this tool as a designer forever I just hope they never take it offline.

Google Maps plus a global any location sun calculator for any day in the year thought time, what more could a designer ask for.
www.suncalc.net



This is the best thing!  Thank you!  I've been looking for this tool for months now
 
Charles Kelm
Posts: 170
Location: Western Washington (Zone 7B - temperate maritime)
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There's also a great iPhone app called Sun Seeker.
 
Sue Jones
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The best tool I've found is the Solar Path Finder. Pricey though, about $300

http://www.solarpathfinder.com/
 
Nicola Marchi
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Best way to calculate inclination is with a protractor and a weight on a string.

Just tie or tape the string to the center point of the protractor and sight down the length of the protractor.

If it's a 180 degree protractor read the angle measure by the line and take the absolute value of it minus 90.
 
Saybian Morgan
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Location: Lower Mainland British Columbia Canada Zone 8a/ Manchester Jamaica
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I'm using this map forever, I have a background in lighting and photography, being able to manipulate the sun's behaviors manualy really helps me wrap my head around time of day, length and cast of shadows, exposure duration, light penetration. It all comes down with being able to play with that toggle and of course project to any time of year with correct sunrise and sunset.  It's tools like these that change potential in such great ways that it beg's for a permie toolkit. 
 
Jack Shawburn
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A bit OT - See where the sun is using Viking Sunstone
http://en.wikipedia.org/wiki/Sunstone_(medieval)
 
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