Which statement is true about factors affecting spray drift?

• A. Spraying during temperature inversions can result in significant long-distance drift
• B. Drift only occurs at high wind velocities
• C. Temperature inversions reduce drift
• D. Drift is negligible in most situations

Answer: (A)

Temperature inversions create a stable layer near the ground that limits vertical air mixing. When spraying under this condition, droplets don’t fall out of the breathing zone quickly and are more readily carried horizontally by the wind, allowing them to travel far from the target. This is why spraying during a temperature inversion can produce significant long-distance drift.

Drift can occur even with light winds, and inversions don’t reduce drift—they often increase it by reducing vertical mixing. Drift isn’t negligible in all situations; under the right conditions, it can be substantial.