What may affect an early morning application even though the weather is clear and sunny with no wind?

The situation described in the question highlights the significance of temperature inversions in aerial application practices. A temperature inversion occurs when a layer of warm air traps cooler air at the surface of the earth, leading to a stable atmosphere. This stability can cause issues with the dispersion and efficacy of the applied chemicals, as the cooler air (which may contain the pesticide) remains trapped underneath the warmer layer.

In the early morning, particularly after a cool night, temperature inversions are quite common. While the weather may appear clear, sunny, and devoid of wind, these inversions can cause the pesticide particles to not properly spread or can create drift if wind conditions suddenly change as the day progresses. As a result, the effectiveness of the aerial application can be significantly compromised, and the potential for off-target movement increases.

This understanding underscores why temperature inversions must be monitored and considered before planning an aerial application, especially in the early morning hours.