What aspect of weather does a psychrometer measure?

A psychrometer specifically measures humidity by utilizing the principle of evaporation cooling. It comprises two thermometers: one that has a dry bulb, which measures the air temperature, and another with a wet bulb, which is moistened. When air passes over the wet bulb, some of the moisture evaporates, causing the temperature reading on the wet bulb thermometer to drop. The degree of this temperature drop correlates with the amount of moisture present in the air, allowing for the calculation of relative humidity.

This ability to assess humidity makes the psychrometer an essential instrument in meteorology for understanding moisture content in the atmosphere, which plays a crucial role in weather prediction and analysis. Other instruments, such as barometers, measure pressure, anemometers are used for wind speed, and thermometers provide temperature readings, but psychrometers are uniquely designed for gauging humidity levels.