Fairfax County General :
Fairfax Underground
Welcome to Fairfax Underground, a project site designed to improve communication among residents of Fairfax County, VA. Feel free to post anything Northern Virginia residents would find interesting.
All you have to do is measure the shadow height of a known object then figure out the ratio of those two, then measure the shadow of the unknown object. Assuming the slope of the ground is the same for each object.
Estimated telephone pole height = 38ft
Telephone pole shadow length = 33.8ft
38 / 33.8 = 1.12426
Antenna tower shadow length = 640ft
1.12426 x 640ft = 719.5 ft
So about 719.5ft. I couldn't see the exact tip of the antenna tower's shadow so it might be a little more or less than that.