"Their actual position is always the "upwind" side so key off that." So...how far upwind might the target actually be in the wind I described above. What is the range in MOA that it might be upwind --- roughly?
In addition to holding left or right for wind drift, how much will mirage affect my shot by making the target appear to move over to one side or the other? What is a typical mirage-induced range of apparent target movement at 5 mph and at 700 yards in bright sunny conditions?
Here's what I do Len. If my target is moving about from mirrage, think of it like this, the target being on rubberbands and the air is making the rubberbands stretch out and back depending on how the air movement along the distance to the target. If the air is steady it will stretch and stay there, maybe letting up a little hear and there as the fluctuates giving it that wavering effect and then it will pull back to the upwind side and be still, maybe for only a moment here and there but where it is still, this is your targets real position.
Now that you've centered on this spot don't move the rifle, watch as the bull returns to the center of the crosshair and stops over and over until your sure it's the true position.
Now you have a baseline to moniter the mirrage direction and guage the speed and duration. You can see switches and letups pretty easy now. The predominant condition is the one I use if there is one, it alows me enough time to get off a shot and not have to wait too long for the same condition to fire another. If you always wait for complete letups, you may have to wait for a while.
Fireing while observing/associating the condition your firing in will teach the rest, and the only best thing I can think of is to have a spotter who reads wind better call the shots for you, which might steepen the learning curve some.
Most of my mirrage happens close to the muzzle from barrel heat after about 4 or 5 rounds, it helps to see the air movement up close which has alot more effect than the movement out just in front of the target. Half way down to the target the wind can still kill you too, it's just that the bullet has already made it that far accuratly first so it don't have much time to act on it.
Hope that helps some, just learning myself.