Prediction of Temperature, Wind Speed, and Actual Vapor Pressure at Different Heights Above the Crop Canopy

Abstract

The movement of chemicals away from the intended target under the effect of weather factors is a serious environmental problem. In order to minimize drift hazard, operators should be provided with a tool that would help them to decide whether or not to spray depending upon prevailing weather conditions. For this purpose, a simple model for the prediction of air temperature, wind speed, and vapor pressure at different heights above the crop canopy was developed. This model is mainly based on the incoming short-wave radiation, soil and crop types, crop height, relative humidity, wind speed and air temperature measured in the field at heights of 4 and 0.8 m, and 1.5 and 0.8 m, respectively, the cloud coefficient, and the fraction of sky covered with cloud. Although many approximations were made throughout the development of the model and no stability corrections were taken into consideration for simplification purposes, results show a good agreement between measured and predicted values. This prediction model can then be a valuable engineering tool that could be used, not only for spraying purposes, but also for many other weather-dependent agricultural operations.