Nate Core Practice Test - Practice Exam, Prep & Study Guide

As relative humidity decreases, the difference between the wetbulb and dry bulb temperatures increases. This occurs because the dry bulb temperature measures the ambient air temperature, while the wetbulb temperature is influenced by the evaporation of water from a wet surface. When relative humidity is high, there is less evaporation happening, leading to a smaller difference between the two temperatures. However, as relative humidity drops, the capability of the air to absorb moisture increases, resulting in more evaporation. This evaporation cools the wetbulb temperature further, creating a larger difference between it and the dry bulb temperature. Therefore, with decreasing humidity, the increased evaporation effect causes a greater disparity between the two temperature readings.