Wind ?

[Don McDowell]

The wind the bullet first encounters will have the first affect on the bullet. Tail wind, head wind, quarter left, quartering right all have a different affect than a simple cross wind. Winds at the peak of the bullets trajectory will also have a big affect.
Mirage is also a wind indicator.
My thoughts and any "calls" I give a shooter are based first on the first 100 yds, then if there are wind flags or something else to use about half way to the target to indicate wind direction/speed, and then the conditions at or just in front of the target. Then you roll all that together do a quick calculation and tell the shooter what you see, and give your best guess as to what if any sight corrections need to be made.
It's very easy to get caught up in minute adjustments, but the prudent thing to do is keep in mind about what sort of foot print a 2 minute group would look like on the target. Then before making a wind call , you need to ask the shooter if that last shot was a good break or not.
Don't chase shots unless they are way off the mark.
Lastly it helps to know what the group size the shooter is capable of delivering , and whether or not the ammunition has been tested good at the range being shot.
Getting one of the wind charts that Shiloh sells will also go a long way to help make good wind calls. Kenny and Jimbo put an awful lot of time and testing into that thing, and it's a true assest to shooters that use it.