What is a key factor influencing the evaporation rate of droplets in aerial application?

In aerial pesticide application, relative humidity plays a crucial role in determining the evaporation rate of droplets. When relative humidity is high, the air is saturated with moisture, which reduces the rate at which water can evaporate from the droplets. Conversely, low relative humidity increases evaporation rates as the surrounding air can absorb more moisture. This influences the effectiveness of the pesticide application because rapid evaporation can lead to smaller droplet sizes and inadequate coverage on the targeted surface, which can diminish pest control efficacy.

Factors such as altitude during flight, type of crop being treated, and spray droplet size are important in aerial application but do not directly affect the evaporation rate in the same way that relative humidity does. Altitude can influence weather conditions and temperature but does not correlate directly to moisture levels affecting evaporation. The type of crop may determine the sensitivity to certain pesticides or the preferred application method, while spray droplet size affects drift and coverage but is not a direct variable in how evaporation occurs based on atmospheric moisture conditions. The direct relationship between humidity and evaporation makes relative humidity a key factor in this context.