As good as the Kestrel is, however, it only reads the wind at the shooter's position--which can be vastly different from what's going on down range. So you can't rely on that single measurement, especially when shooting in hilly regions where the wind moving through canyons will swirl and shift at a moment's notice. To master this requires learning how to read mirage. (This assumes that the wind isn't blowing too hard. After 12-15 mph, mirage lays down and becomes difficult to impossible to access.) And this is where the art of reading the wind--honed by practice--comes into play.