For 10 points, identify this measure of how much moisture is in the air.
One way of measuring this is equivalent to the mass mixing ratio, while the volumetric measurement is not usually used. One simplified device for measuring it is the psychrometer, which consists of two thermometers and comparing the current conditions to those of saturated air at the same temperature yields the relative measure of this. That saturation point is known as the dew point and using both temperature and this measurement allows one to calculate the heat index. For 10 points, identify this measure of how much moisture is in the air.
One way of measuring this is equivalent to the mass mixing ratio, while the volumetric measurement is not usually used.
{humidity} [or relative {humidity}]