A sling psychrometer measures _________________________.

A sling psychrometer is a specialized instrument used to measure relative humidity in the atmosphere. It consists of two thermometers, one with a dry bulb that measures the ambient air temperature and another with a wet bulb that has a moistened wick. As air passes over the wet bulb, the water evaporates, causing a drop in temperature. By comparing the readings from both thermometers, one can determine the relative humidity of the air.

Understanding relative humidity is crucial in various fields, including agriculture and aerial application of pesticides, as it helps assess the potential for evaporation and the effectiveness of pesticide application. Higher relative humidity can reduce evaporation rates, while lower humidity can enhance them, influencing the application timing and technique.