Environmental Engineering Reference
In-Depth Information
21 March
Altitude = 90° −22° −0°
Altitude = 68°
21 June
Altitude = 90° −22° + 23·5°
Altitude = 91·5°
(which means the sun is slightly to the north of an overhead sun position). Try this out for
your own latitude to work out the range of solar altitude from winter to summer.
The presence of Earth's atmosphere has a dramatic effect on the amount of radiant
energy which reaches the surface, but we can illustrate the essentially astronomic controls
of the input either at the top of the atmosphere or by assuming there was no atmosphere;
the result is the
