View Full Version : How much garden is always in shadow?

2009-Dec-18, 01:46 PM

I have a house 6 metres high. At noon of summer
solstice the house will cast its shortest shadow in
the year. Question: How long the shadow is?

(In practical terms: how much backyard is ALWAYS
in shadow? So I can put there some hammocks :whistle: )

Additional data:

Earth's axial tilt is: 23.44
The house is located at latitude 42.67 N

Proposed solution:

At this latitude the sun can reach this maximum inclination:

23.44 + (90 - 42.67) = 70.77

tangent = (opposite/adjacent)

tan (70.77*pi/180) = (6 mt / x)

2.8668 = (6 mt /x)

x = (6 mt / 2.8668) = 2.093 mt

Are 70.77 and 2.093 mt correct?

Thank you ! (I apologize for exploiting you).

And Merry Christmas! :)

2009-Dec-19, 07:54 PM
The numbers look good. However, on the summer solstice, the sun rises and sets significantly north of due east and due west (northern hemisphere). So unless there are more buildings, fences, trees, etc, northeast and northwest of your hammock zone to cast additional shadows, the sun will still be able to shine in the 2 meter zone you computed. This may not be particularly bothersome to your hammock, as it will be early morning and late afternoon sun.

2009-Dec-19, 08:02 PM
Good answer, tony, and the computed answer (still haven't checked it!) is only for high noon, it looks like. The actual number will be smaller depending on the time of day, until it is zero early morning and late evening.

2009-Dec-19, 10:09 PM
Science: It's not just for finding stuff. It's also for figuring out where to place your dang hammock.

This thread amuses me in so many ways.

I have nothing helpful to add. Math makes my head hurt.

Paul Beardsley
2009-Dec-19, 10:20 PM
I have nothing helpful to add either, but I'd like to mention how envious I am. I'm currently reading a novel about a garden in Tuscany (The Savage Garden by Mark Mills) because I don't have one myself.

2009-Dec-22, 01:39 PM
Thank you, but it's a house like everybody else's :)


(notice at south my neighbour, the millionaire...)

I came to this forum because of this house: until today I have always lived in town or in a suburbia compound under trees, so now it's the first time I can see the whole sky at home (no houses or trees around to block view).

2009-Dec-22, 02:22 PM
That changes things slightly. If the house is not oriented due north and south, the angles will change. It looks to me like you'll have better afternoon shade...

I assume that's your house in the back, and the back yard is more to the north?

2009-Dec-22, 06:22 PM
You're right it's not oriented exactly north-south... I didn't notice that...

It's just a small error anyway... I should multiply the 2.09 mt for the cosine of the narrow angle between north and house's orientation... -5% roughly

2009-Dec-22, 06:32 PM
Cool... on google maps I can see the air force base...


I wonder if the clouds are real or just to cover up the control tower etc...