Say I want to know the number of hours of sunlight
that a spot in my garden will get over a day. Say I am
not largely worried right now as to the total energy,
just the amount of sun.
If the spot is flat and there are no nearby walls, I
can figure the hours of light by looking up the
sunrise and sunset times and subtracting.
On the other hand, if there are nearby walls and
trees, I need to know the angle of the sun off the
horizon and the sun's path, the height of the wall and
distance to my patch of ground, and a bunch of trig to
figure out how much sun the area gets.
Does anyone know of a resource to help me make these
calculations?