日陰 - 太陽の動きを計算 app for iPhone and iPad

This application simulate direction and length of sun shade.
It uses GPS location and the clock of iPhone.
The center compass displayes the direction of sun shade.
The tree shade displays the length of shade.
The numerics displays the length of shade of the tree of which length is one.
This application can change the date and the place of which calculate direction and length of shade.
Rotate your iPhone, and you can see the global map displaying night area and various graphs.
I think it is a good tool to know whether you disturb the person you call abroad.