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How to plan a sundial?  RSS feed

 
Rebecca Norman
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Location: Ladakh, Indian Himalayas at 10,500 feet, zone 5
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food preservation greening the desert solar trees
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I didn't know where to put this but since a sundial is a solar clock I thought I'd put it under solar. Anyway...

A sundial would be nice project for our students at this largely solar powered alternative school. We've got mostly sunny days, and India doesn't do any daylight savings time. Can anyone please steer me to websites with simple info on how to lay out a sundial? We've got flat ground for a small one, or a south facing slope that could be seen from far away and might be cool.

Thanks!
 
Darryl Roederer
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Just a guess here, but I'd go to youtube and search for building a sun dial, or Google for that matter
 
John Elliott
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Step 1: Find where true north is. This is best done on a clear night when you can identify the Big Dipper and the North Star.

Step 2: Shove a stick in the ground and line it up with the North Star. This may require laying on the ground and aiming the stick like you would aim a rifle. Now you have your gnomon.

Step 3: Next day, when the sun is out, calibrate your gnomon by observing its shadow. At local solar noon, the shadow of the stick will point to true north and the shadow will be the shortest of the day.

Step 4: Read up on analemmas so you can correct for the eccentricity of the Earth's orbit that makes the sun's position relative to the gnomon vary from month to month.
 
Terry Brown
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ideally you need to do these few things to get it basically right.

1. find YOUR position on the globe - all you need is the line of LATITUDE - something like 54 degrees

2. you need to make the vertical bit that sticks up at the same angle to the face of the sundial

3. set the sundial flat using a spirit level. so now you have the face 90 degrees to the sun at high noon [note high noon or when the sun is directly overhead is local time as its different as the sun moves across the sky]

4. the sticky up bit lol [well I don't know what its called!] - point that towards north using a compass.

you will have to work out the hours on the face - this is quite tricky.. I did this once with a book I found - works very well if you follow the instructions.

you may be able to find a ready made face pattern.

theres a calculation to marking them out on the face - not easy
 
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