All wind reports in the Mesonet Spray Tool are at a height of 3 feet for ground applications which can range from 28% to 85% of a standard height wind depending on conditions. For maximum applicability across a station's coverage area, the 3-ft wind is derived using EPA methods from measurements made at a greater height (either 10 or 33 feet).

Inversion

A temperature inversion (inv) is a condition when cooler air is trapped under warmer air. It is determinded from the vertical temperature difference (either 3 and 10 ft or 6 and 33 ft). Inversions allow concentrated clouds of pesticide to be transported long distance with being broken up. Inversions are closely tied to times when the sun is unable to heat the earth's surface: during the night and the first/last hour of the day.

ΔT is the term used in the pesticide applicator community to refer to wet bulb depression. Roughly speaking, it is the difference between the temperature of the air and a water droplet suspended in it (°F). It combines the effects of both temperature and humidity to give a good picture of the evaporation rate of a pesticide droplet. At low ΔT values, low evaporation rates mean that droplets can travel extended distances increasing drift risk. At high ΔT values, increased droplet evaporation (in the air and on surfaces) can reduce product effectiveness. All else being equal, the impact at high ΔT values is less pronounced when using COURSE or greater nozzles. ΔT is not restricted on labels in the US.