Surface air flow in the Cauca river valley
Introduction
Wind is air in motion; therefore, when we talk about this phenomenon, we are referring to the horizontal movement of air. At the surface, air tends to flow from areas of high pressure to areas of low pressure. The trade winds are a clear example of this. The trade winds flow from the mid-latitude high-pressure systems in the north and south toward the nearly constant equatorial low-pressure system. Another example of this is coastal circulation cells, where the difference in thermal properties between the ocean and the land generates sea-to-land breezes during the day and land-to-sea breezes at night, in response to changes in surface temperature and pressure.
Among the factors influencing agriculture, wind has been considered only for its role as an input in the equation for generating evapotranspiration values (e.g., Allen, 1998) and for establishing risk zones due to the mechanical effects of wind on cultivated plants, agricultural infrastructure, and soil (wind erosion). In such situations, the vector nature of this variable is disregarded, and it is preferred to consider it as a scalar, that is, as a value of airflow velocity, or maximum gust in some cases. Consequently, the concept of a wind field, widely used by environmental engineers, is not common among agronomists, and generally among production biologists and even agricultural engineers.
The wind field is simply the spatial pattern of the wind, that is, the prevailing wind direction and speed in a given location or region at a given time. The results presented here correspond to the analysis, at different time scales, of wind speed and direction data recorded at the stations of the sugar and energy sector's meteorological network. At the network stations, the wind sensor is located 10 m above ground level, unlike agroclimatic stations, where the sensor is located 2 m above ground level. The scheduling of controlled agricultural burns is the reason for the placement of wind sensors at the agro-industrial stations.
