MDARD Michigan Core Pesticide Applicator Practice Exam

What occurs during a temperature inversion that contributes to pesticide drift?

1. Cold air rises

2. Warm air traps small pesticide droplets near the ground

3. High pressure systems result in strong winds

4. Chemical reactions increase volatility

The correct answer is: Warm air traps small pesticide droplets near the ground

During a temperature inversion, warm air sits above a layer of cooler air near the ground, creating a stable atmospheric condition that can hinder vertical mixing of air. This stability means that any small pesticide droplets released into the cooler air can become trapped. As a result, these droplets remain suspended rather than dispersing and dissipating upwards, which can significantly increase the potential for pesticide drift. The accumulation of pesticide droplets near the ground can lead to unintended exposure in non-target areas, making this phenomenon a key concern for applicators. The other options describe phenomena that do not accurately reflect what happens during a temperature inversion. For instance, cold air does not rise; instead, it remains below the warmer air, reinforcing the inversion layer. While high pressure systems can influence weather patterns, they are not directly related to the mechanism of pesticide drift caused by inversions. Similarly, increased volatility from chemical reactions is not a defining characteristic of inversions and does not contribute directly to the entrapment of pesticides in the air near the surface. Understanding these dynamics is crucial for responsible pesticide application and minimizing the risk of drift.