Your question has been answered already, but I’ll amplify and augment.

Mirage, as well as all other wind indicators (bugs, dust, grass, wind flags, etc) will fool you. It’s a giant PITA. Let’s say you try to determine the wind at your firing position and also in 100 yard increments out to the target. If the wind is variable or switchy, it will most likely change by the time you’ve completed your analysis and are ready to break your shot. If the wind is indeed different at various ranges, it IS switchy and will be a real bastard to read.

I can’t tell you how many times I’ve seen left to right wind at my position and at the target and have the bullet go the other way. It’s mystifying and frustrating, but it’s reality. The composite wind direction (the net of all the wind conditions) can only practically be determined by shooting.

That’s not meant to discourage you from taking delfuego’s good advice to practice, but rather to calibrate your criteria for success. It ain’t easy, and it isn’t even always possible. Still good to work at it, because we all get better with reps.

I’ve been known to send my first shot on a stage at a match at the base of the target stand. It’s a guaranteed miss, but if I can get a read on the composite wind, I greatly increase my chances of hitting the rest of the targets. The whole “first round hit” thing at meaningful distances is as much luck as anything else in difficult wind conditions.