By Guy J. Sagi
It doesn’t take a degree in physics or a working knowledge of the theory of relativity to harness the power mirage to improve your shooting. In its most basic application, it can be an advantage in hunting, explain one problem at the range, and, with practice, provide an improved ability to hit the bullseye at distance.
At the very foundation of reading mirage is the basic principle that light often bends when passing through different, even transparent, materials or those with different densities. Although not classic mirage, shooters witness the effect every day when they put something in a glass of water. No imagine if the tip of this ballpoint is the bullseye—exactly where would you put the crosshair?
You digested most of the science in elementary school and the phenomenon surrounds you daily, so relax. No test follows this primer, which is hopefully entertaining enough that is gets you looking for mirage at home and on the range—because proficiency cannot be created by reading an article. Practice is the only way to harness this power.
Classic road mirage reflects the sky, which provides the road a shimmering-blue, waterlike look. In this case the tree line behind is refracted/reflected toward the viewer.
Deer hunting provides a simple application, despite the fact shots are usually within 100 yards. All of us have decided to close the gap once we’ve spotted our quarry at a distance too long to deliver an ethical shot. However, wildlife has an uncanny sense of smell, so approaching from downwind to minimize the chances of detection is the best option.
Unfortunately, wind is fickle. At the very least you can expect it to vary in speed between your position and that of the animal, but topography can also create a situation where it’s moving in a different direction entirely. Add occasions when winds swirl around a canyon, and mirage becomes a powerful tool.
This image of power lines at about 500 yards are not the result of Photoshop manipulation. A “boil” is creating a fuzzy group of “ghost wires” above each one. At this distance holding slightly under a target in these conditions may not be necessary (depending on rifle, load and required precision), but the image illustrates the manner in which some mirage can falsely add elevation to a target.
Yes, reading leaves/branches along your preferred route is the fastest method, but that requires enough breeze to move foliage. Wind-reactive plants are also mandatory, which is a challenge in many portions of Afghanistan as well as a few of the Sonora Desert’s most popular mule deer hunting areas—where monolithic saguaro cacti barely budge in gale-force winds.
Light bounces off a target, transmits through the air, and finally it’s collected by our eyes for the brain to process. Sounds simple, but nature can alter things during its long trip to our scope.
Light can bend, or refract, as it passes through materials of different densities. You witness the phenomena every time you visit a restaurant, where a straw in a glass of water seems disjointed at the point it submerges.
These railroad tracks are used to this day, but they have a tendency to look like a wet noodle on sultry days with a high sky. Of note is the upper left hand corner, where the tracks meet a road crossing. Notice how the right track is “smudged” or “fattened” toward the left, which indicates a breeze of 12 miles or less from right to left. The rest of the track, sheltered from the wind by trees, appears to have a “boil” elevating random sections of the steel.
Different densities of the same material can produce a similar effect, one you often see when driving in the summer. That distant “water” on the roadway you never seem to reach is a textbook definition of mirage.
When first learning to read mirage, it sometimes helps to focus on the target, then move that focus so that it is slightly fuzzy (out of focus). In this case the railroad tracks in the foreground are clear, and the “boil” behind is easy to see.
Here’s how it works. Blacktop collects heat in the sun, and then warms air directly above, reducing its density. Higher in the atmosphere, though, there has been no change. When light from the sky passes from the dense material into a “lighter” one, it refracts enough to create a shimmering, blue reflection on the roadway ahead. Bear in mind, though, hot temperatures are not required. I’ve seen it on the ocean in Alaska and above parked cars in Virginia, both cases in which the temperature was well below freezing and the sun was shining.
High contrast targets with very visible vertical lines will help beginners sport mirage more quickly. Yes, this is a real, non-damaged road sign seen through a mirage I’d guess as boiling.
Thankfully, there are some things that provide a solid foundation, starting with optics. Firmly anchored, 15X or higher-magnification optics are best for reading mirage—like the Nikon 20-60. Naturally you focus on the target, but don’t be afraid to adjust to make the image a little fuzzy. Sometimes that helps pull it out, and down the line it’ll help you DOPE (Data On Previous Engagement, or so I’ve been told) the wind better along the entire flight path.
Mirage on the pavement would make navigation something of a challenge for newcomers to town, except for the fact that it always disappears upon your approach. Notice the distortion in the nearby road sign, and the more distant 45 miles per hour speed limit sign, which seems to indicate a slight right to left wind.
Don’t select a practice distance too close. Remember the road example. The big pool of water is always distant, and regardless of your speed you never seem to get your wheels wet. Three hundred yards or further is a good starting point, on a warm and sunny day, but don’t be surprised when down the line you witness the effect at shorter ranges.
In this unaltered image of a road sign taken this summer, it’s obvious how mirage can distort what we see when looking at a distant. The strong vertical lines will be moving and shimmering when you watch them through a scope and their orientation during movement indicates wind direction.
Use a black or dark target, one with highly contrasting vertical lines. There’s less energy required to “bend” the air than move flags/leaves, so you might as well see all the information possible in the beginning.
Expect mirage to disappear as wind speeds approach and exceed 12 miles per hour. Perhaps the air densities effectively mix at that point, but it’s going to get tough or impossible at those velocities.
The sweltering heat rising up off this road has provided lots of waves in a classic mirage that is reflecting the trees behind. Notice how the distant road seems to be wavy in form along its side, with a boil elevating random sections of the view.
An elite former military sniper told me in an interview that wintertime in Afghanistan often made reading mirage a challenge, regardless of wind speed. That’s when he’d find a dark object near the target at the same elevation and read mirage just above it—black hood of a car, trash can lid, etc.
There’s little, if any, distortion in the nearby corn field, but the more distant solar panels are so distorted by mirage the that back row is no longer straight—it looks more like a saw blade in these conditions. When first practicing, make sure you give yourself enough distance to the target that mirage is visible.
The Tales It Tells
Volumes have been written about intensity of the mirage, wind value, direction and speed. It can be information overload for beginners and some of us who’ve dabbled in the black magic. Bill Porter probably summarized the basics of information interpretation best in the Smith & Wesson Shooting Academy’s Winter 1999 NFTC Newsletter. “You will see it elongate the target. If the wind is blowing from left to right you will see the right side of the target get bigger. This area of the target will appear to swell in the direction the mirage is moving.”
As for hunting applications, don’t expect the winds to be steady throughout canyons like this. Branches may not be moving, but even a slight wind can push your scent downwind and alert your quarry.
How much you adjust your windage hold is determined by a host of ballistic variables, but at least you now know which side of the bullseye in which you should hold (assuming that’s the only breeze at the time). Take serious notes every time you practice and it won’t be long until you’re translating the severity of the apparent deformation into the precise point you should place the crosshair. Stick with one notebook per rifle, and stay with the same ammunition/bullet combination (at least in the beginning). Changing ammo introduces a host of other variables, including a different ballistic coefficient and flight time, which alters how long the wind has a chance to change point of impact.
The wind in this valley could be going in the opposite direction as on the ridgeline. There may be no wind at all—or it’s too subtle to move even the dried grass.
Keep it simple and you’ll be surprised how fast you can dial into the breeze. In most of the classes I’ve attended, the instructors take it a step further by recommending you dial your scope for elevation and hold for windage—one less thing to worry about during mirage practice.
When learning mirage, and windage holds, detailed note taking is critical—otherwise you start over every time you go out. Also, keep one notebook for each rifle and load.
When there is no wind at all, but conditions are right for refraction, mirage can literally boil straight up, which can make the bullseye appear higher than it really is. Military marksmen adjust for the effect by aiming slightly lower on the target on warm and steamy days. At 300 yards, failure to do so would be of negligible concern, but push that distance to 1,000 or 1,500 and the oversight can have a significant impact on shot placement.
Using mirage to DOPE the wind requires a good, solid optic on a sturdy mount to read the subtle messages from hundreds of yards away. Some long-distance schools team shooters into pairs, with one calling windage holds as he reads mirage—take my word for it, shooting is the easy part.
In addition, even if you don’t have access to a 300-yard range, there’s another frustrating “boil.” Deliver too many shots, too fast, heat your barrel, reduce air density above it (right in front of your scope) and you might as well hit the road for the day because you’ll be chasing that mirage-elevated bullseye around all day.
There’s a lot more to delivering precision shots at distance that just proper form and trigger work. For more long-distance shooters, mirage is part of the equation.
Word of Caution
If you expect instant expertise from this article, Col. Clive R.E. Halnonan has a warning in his book Shooting Sport Technique and Practice. “The ability to read wind by mirage can only be acquired by experience,” he wrote. “There is no yardstick, and no tables or calculators illustrating degrees of wind strength and direction can be applied. To the experienced marksman, mirage is the truest guide as it conveys to him an ever-moving picture of the wind through which the bullets travel.”
Shooting from ridgetop to ridgetop means by the time the bullet arrives on the other side, wind direction may have changed or stopped completely. Even a rudimentary understand of mirage can help shooters connect.
Despite my fascination with all things physics, I learned that lesson the hard way at Gunsite’s long-range course, where one student sits behind a scope and calls windage adjustments, while his training partner works the trigger. It took at least an hour to get my hold calls right during the course. It was exhilarating when that clang finally came back from nearly 1,000 yards, but then the wind shifted, I started over, and Col. Halnonan’s wisdom was obvious.