What are the two main types of humidity measuring techniques?

The two main types of humidity measuring techniques are psychrometric and capacitive methods. Psychrometric techniques involve measuring the temperature and humidity of the air using a psychrometer, which typically consists of a dry bulb and a wet bulb thermometer. The difference in temperature readings allows for the calculation of relative humidity based on the principles of evaporative cooling.

Capacitive methods utilize sensors that measure humidity by detecting changes in electrical capacitance caused by the absorption of moisture by a hygroscopic material. As the humidity in the air increases, the dielectric constant of the material changes, which alters the capacitance and allows for the calculation of relative humidity.

Other options, while they mention different forms of measurement, do not represent standard or widely accepted techniques specifically dedicated to measuring humidity in atmospheric studies.