Home Made Clinometers (For measuring
altitude / elevation/ vertical angles.)
Find a circular 360 degree protractor with a solid center and a 6" or longer
clear plastic ruler that has a line down the center in the long direction. Scribe
and carefully cut a straight line from the edge of the protractor from 110 to
250 degrees. Plastic cutters are available and a sharp knive can scribe plastic
in the opposite direction as cutting. Drill a small hole in the exact center
of the protractor the size of a small bolt or thumb tack. Drill another hole
on the center line at one end of the ruler. Attach the two with a very small
bolt or tack. You can cover a tack point with an eraser. Add a counterweight
like a large washer to the center bottom of the ruler as a counter weight. Make
sure it hangs vertically and swings freely. Adjust the counter-weight with the
cut edge of the protractor against the bottom of a level that has been leveled.
The Sun's Shadow
Measuring Sun Set Angle at Horizon
To use this clinometer, site over the cut edge at 110 and 250 degrees with the
ruler pendulum hanging down free. DO NOT LOOK AT THE SUN. When the cut edge
is pointed at what you want to measure the altitude of, press the ruler and
protractor together and read the angle from the scale. You can watch the sun's
shadow on the 110/250 edge by pointing it at the sun and looking at the sun's
shadow on your finger. Make sure you use the 0 to 90 degree scale.
If you make one from a 10" or 12" protractor and carefully adjust the counter-weight,
it can read angles with up to 1/2º degree accuracy. Most larger protractors
have a center bar and you must file an notch in the exact center and use tape
to make a center pivot. Don't cut the protractor at 110 and 250 points but attach
a bar as a pointer. Most computer sun position programs are not this accurate
and you usually don't need this accuracy. Navigation and surveying programs
are much more accurate.
Sun's Shadow from Large Home Made Clinometer
Another style: Buy a "Deck and Rafter Square" from Ace Hardware or a "Polysquare"
from other hardware stores. Attach a string and weight to the notch at the "0"
inches. Let the string hang and measure the angle the inch scale is pointed
at or held against. Point it at the sun and watch the shadow on your hand. Read
degrees with string.
Measuring Sun's Altitude with PolySquare
To determine the sun's approximate path at sunrise and sunset, set the angle
of the clinometer at what angle the sun moves in relation to the horizon. (See
General Sun Information)