Calculating the sun's shadow / Courtyard maths?

[dibbers006]

The initial message was deleted from this topic on 15 December 2023 at 23:01

[SpeckledJim]

The maths is very easy, but you'll need to find or measure the position of the sun in the sky at various points of the day and year.

[vetrof]

http://solarelectricityhandbook.com/solar-angle-ca...

Edited by vetrof on Monday 12th June 14:28

[21TonyK]

Not sure how accurate it is but Sketchup has a facility to show shadows cast based on time of year and day.

[DIW35]

I know from my photography that there is an app out there that will tell you where the sun is at any given time on any day, but for the life of me I can't remember what it's called. If you Google sun position or similar, you should find it.

[V8FGO]

There is a Nautical Almanac on Google play that will give you

Sun azimuth and height angle for a given day and hour.

Just run it for 20/21 June and December and each hour from sunrise to sunset.
Calc the shadow length and plot for each hour, this will give min max shadow arcs across the area.
Actually scrub that. Just work it out for say 0600 12:00 and 20:00 for June and 07:00 12:00 and 16:00 for December. Then plot that shadow length for each given time on that times azimuth from say 4 points on the wall / fence to get the shadow area.
Dont forget you will need to know North at your location.

Edited by V8FGO on Monday 12th June 15:01

Edited by V8FGO on Monday 12th June 15:43

[red_slr]

years ago I was using a website which calculated shadow it was a pretty easy to use thing, it also too the lat / long of the location. I will try and dig it out.

[red_slr]

find my shadow .com I think it was.

[nammynake]

If I understand what you're trying to do then you can relate the angle of the sun relative to the ground (theta) using simple trigonometry:

Tangent (tan) of the angle 'theta' (in radians) is:

tan (theta) = Opposite / Adjacent; where 'Opposite' would be the wall height and 'Adjacent' is shadow length. So:

tan (theta) = wall / shadow

Theta is the angle in radians, so you need to convert the sun angle in degrees by multiplying by 2*pi and dividing by 360.

e.g. For a Sun angle of 45 degrees = 45*2*pi/360 = 0.79 radians. The Tangent 0.79 is 1.

This would give a shadow = (wall height / 1). So a wall of 1m would give a shadow of 1/1 = 1.

[ColinM50]

Here you go, this'll tell you the suns position each day. First bit is for US, just scroll down and fill in your location

http://aa.usno.navy.mil/data/docs/AltAz.php

[so called]

If you calculate for 5deg increments then you will have the basic accurate details which will carry from worst case to best case answers applicable for all days of the year, regardless.

Edited by so called on Tuesday 13th June 13:05