You can also try making a simple barometer. If you are really interested, there are some Interesting twists to measuring pressure. Surface relative humidity You can use a wet and dry bulb hygrometer or take advantage of nearby resources such as airports or weather facilities where such observations are taken. You can also try making a sling psychrometer for this measurement. Ambitious folks, particularly in computer classes, may want to go through the whole calculation .
Relative humidity is recorded in percent.
We request information about the surface which affects what the satellite sees. Also of interest is whether the ground is very wet from a recent rain. Keep in mind that the satellite sees an area of about 1 square km at a time, so describe the dominant surface cover for an area of about that size around your school. If you're interested, you can retrieve some historical data for the US from the National Climate Data Center .