Shadow Length at Equinox by Latitude & Stick Height
Computes Shadow Length for the Sun at equinox given a Latitude (really angle from the sun) and some Stick Height (given as distance from center of Earth). Values are in kilometers (km) so 0.005 = 5 meters. Stick angle is from North Pole - but latitude is from equator - sorry. If it's not the equinox you'll need to find the latitude of the Sun and 'rotate' the angles to find your relative angle. Adapted from Mick West's 'Obscuration by the horizon'