Which weather condition can greatly increase the risk of pesticide drift?

High temperatures can significantly increase the risk of pesticide drift due to the influence of thermal dynamics in the air. When temperatures rise, the air can become less dense and more turbulent, leading to increased evaporation of pesticide droplets. This process can create lighter particles that are more susceptible to being carried away by wind currents, resulting in drift away from the intended application area.

Moreover, high temperatures can also affect the viscosity of the pesticide formulations, making them more prone to atomization during aerial application. When pesticides are atomized into smaller droplets, they can easily be transported by even slight winds, increasing the likelihood of unintended exposure to non-target areas, such as neighboring crops, wildlife, or water bodies.

In contrast, high humidity conditions tend to stabilize the air and can reduce evaporation rates, leading to a lower risk of drift. Calm winds provide a controlled environment for application, minimizing the movement of pesticides away from the target area. Overcast skies might also help to lower temperatures and reduce evaporation, further decreasing drift potential.