While it takes time, coaching and practice, learning to read mirage will help you own long-range shooting.
Why it's important to read mirage:
- Gives you not only wind speed, but also value.
- You can better estimate the wind's effects down range.
- Requires less reliance on technology to make an accurate shot.
Reading wind is truly as much art as it is science. While a wind meter can’t always give you the correct windage for a long-range shot, if you read mirage in conjunction with a wind meter it can do as much to teach you how to read wind as years of shooting experience. Learning to read mirage normally requires spending time with someone who can read mirage and is willing to share it, or you can spend a lot of experimental shooting time.
Reading mirage involves observing light waves as they’re disturbed by heat, and using the amplitude and frequency of those light waves to determine the required amount of windage to hit center. The great thing about using mirage is that it shows wind value as it shows speed. An 8 mph wind blowing straight up or downrange appears as a no-value wind, and it looks almost the same as a zero-wind situation. A half-value 8 mph wind looks almost exactly like a full-value 4 mph wind. The reason for this is that wind speed is only observable as to its relative speed perpendicular to the line of sight.
To read mirage, focus your spotting scope about halfway between you and the target. The amplitude shows up better on a horizontal line, so if there is one, look for the mirage as it distorts that line. In high power, I focused on the top of the target frame at 600 and 1,000 yards, and the bottom of the frame at 300 yards. The faster the wind speed, the faster the mirage will appear to move. At zero wind value, it appears to not move from left or right, but rather it appears more as a boil. The slower the wind, the greater the amplitude of the waves, and at wind speeds above about 10 mph it almost fl attens out. Above that speed I think in terms of frequency: Imagine a sine wave that flattens as it speeds up.
More Long-Range Shooting Info:
- Buying the Perfect Precision Scope
- Ballistics Basics: Initial Bullet Speed
- The Effects Of Air Temperature On Bullet Flight
- Mils vs. MOA: Which Is The Best Long-Range Language?
Your ability to learn from experience is limited to your ability to shoot. If you can only hold within 2 MOA, your ability to judge your wind calls will be limited to that level. Learning from experience is best accomplished by coaching, or by listening to a good coach while he or she coaches an excellent shooter on the line. Under those circumstances, you can instantly see if the wind call is good or not. When shooting with a coach, the shooter needs to advise the coach if he calls a shot left or right because a shot that comes up right of the coach’s estimate will make the coach believe the wind has more value than is being seen.
Learning Mirage From A Wind Meter
To use a wind meter to learn to read mirage, find a large, flat area unobstructed by fences, buildings or trees. Read the wind speed with the meter, factor in the value that’s based on wind direction, and observe the mirage. Rotate the scope directly into and away from the wind and notice how a boil appears. Observe the difference between a half- and full-value wind. I suspect you’ll learn to read mirage much faster that way than from experience.
It’s also important to receive instant feedback on your results. This can be done where a dust signature can be observed, though spotting hits in dust can be deceiving. Obviously, it works very well on known distances, in ranges with pits or when shooting electronic targets, but there’s another affordable option in the form of remote target cameras. With a remote target camera, you can instantly see the results of each shot and most will indicate the location of the most recent shot. They’re a great aid to learning to read wind without the assistance of another person.
The ability to reliably read wind for long-range shooting requires time, and a lot of range time, but there’s nothing more satisfying than making the wind call on a long shot in a crossing wind — and nailing it.
Editor's Note: This article originally appeared in the December 2018 issue of Gun Digest the Magazine.