It is critical to measure relative humidity, wind speed and wind direction in order to minimize waste and maximize safety  when spraying. Many locales regulate the maximum permitted wind speed during spraying to minimize spray drift. In hot, dry conditions, expensive chemicals may evaporate into the air rather than onto your crops. Delta T allows you to accurately assess acceptable spraying conditions to ensure you’re within guidelines and help you select the right spray nozzle. The Kestrel 3500 DT is the difference between wet bulb and dry bulb temperatures. Its an accurate predictor of chemical evaporation rates. The Kestrel 3500 Delta T incorporates barometric pressure correction in its wet bulb temperature calculation, ensuring accuracy even on low pressure days, at high altitudes, and in very dry weather when the Kestrel Delta T pocket meter monitoring is important. No other pocket weather meter offers this feature with this level of accuracy.