Anemometer is blowing on the back of the cup on the opposite end of the cross. Since a hollow hemisphere has a drag coefficient of .38 on the spherical side and 1.42 on the hollow side, more force is generated on the cup that is presenting its hollow side to the wind. Because of this asymmetrical force, torque is generated on the axis of the anemometer, causing it to spin. Theoretically, the speed of rotation of the anemometer should be proportional to the wind speed, because the force produced on an object is proportional to the speed of the fluid flowing
Radon measure regular, and locally finite, and inner regular for open sets. It coincides with "m" on compact and open sets, and "m" can be reconstructed from "M" as the unique inner regular measure that is the same as "M" on compact sets. The measure "m" is called moderated if "M" is σ-finite; in this case the measures "m" and "M" are the same. (If "m" is σ-finite this does not imply that "M" is σ-finite, so being moderated is stronger than being σ-finite.) On a strongly Lindelöf space every Radon measure is moderated. An example of a measure "m" that is