In order to see this mirage the Sniper must focus his spotting scope on an object at midrange, then place the scope back onto the target without readjusting the focus. As observed through the telescope, the mirage appears to move with the same velocity and direction as the wind, except when blowing straight into or away from the scope. Then the mirage gives the appearance of moving straight upward with no lateral movement. In general, changes in wind, up to 12 mph can be readily and accurately determined by observing the mirage. All telescopic sights have windage adjustments that are graduated in minutes of angle or fractions thereof.
Snipers use min.
After finding wind direction and velocity in MPH, the Sniper must then convert it into MOA using the following formula. This formula is a rule of thumb only and is used as a starting point. Practice and keeping a good data book are the ultimate goals and tools. This can be helped by practice and a good data book . Temperature affects the firer, ammunition, and air density.