Notes for Lab #5 - Earth Sun Geometry

In lab I set up four globes with the earth's axis pointing towards the North Star (Polaris). I then showed the relationship of the Sun's rays to the earth's surface.

I then showed everyone how to determine the noon zenith angle without using trigonometry and geometry.

Noon Zenith Sun Angle = (difference in latitude between the solar declination* and the location of interest)
        * solar declination - latitude where the noon sun angle is 90^o

^{The solar declination can be determined using the formula:}

^{solar declination = 23.5 * sine (N)
where N = the number of days to the closest equinox, expressed in degrees.}

^{The solar declination can also be determined using an analemma (see below).}

Questions 2 and 3 can be completed using the analemma.

Calculating solar intensity can be done using geometry and triginometry as shown in the lab manual. It can also be done using the table below. The table represents the calculations done by someone else (we should thank them).

The interactive computer exercise is not required.