When “Prevailing Wind Directions” Don’t Prevail

What’s counterintuitive about places where there are typical “prevailing winds” like the plains of Colorado where these images were taken, is that sometimes, the prevailing wind direction is anything but, over very short time spans. These images – with wind directions differing by nearly 180 degrees – were taken only a few minutes apart. Wind speed and direction are required variables in calculating flow rate from measured plumes so measuring the wind field is almost as important as measuring the plume concentration profile and shape itself.