How To Read Mirage and Estimate Wind Speed Using a Spotting Scope

Summary: A spotting scope is a valuable tool for cutting through a mirage and reading wind speed. In this article, we walk you through a guide on how to learn to use them, and we will also recommend some of our top spotting scopes.

A mirage will distort your view of a target. Wind will push your bullet’s trajectory off its usual path.

A spotting scope will help cut through both challenges if you know how to use one. Here are some tips that will help you become more accurate under these conditions.

We explain what a mirage does. We tell you how wind affects bullet performance. We explain how the two work together to prevent you from getting a proper shooting solution and sight picture.

How does a spotting scope help you read mirage and estimate wind speed?

Your spotting scope will tell you about the wind based on the angle of the mirage. With that information, you make an educated guess about the wind speed. A mirage will distort your view of the target and wind can knock your bullet off target. Learning to use a spotting scope to overcome these challenges.

With some practice, you can use a quality spotting scope to find your target, check your zero and shoot better and tighter groups. Below, we tell you how to do this and recommend a few quality spotting scopes.

How to Use a Spotting Scope to Read Mirage and Estimate Wind Speed?

To use your spotting scope to read mirage and estimate wind speed, you need to take a few steps.

1. Find your target.
2. Get the distance to the target.
3. Look through your spotting scope.
4. Watch the distortion, making note of the angle. Use a clock face for this. Distortion is 0 – 12 o’clock; light – 11 or 1 o’clock, Medium – 10 or 2 o’clock; heavy – 9 or 3 o’clock.
5. Use ballistic charts to compute the wind drift for your load. Every bullet is different so you need the chart for your ammo. These are available online.
6. Do the math. “The formula for wind load is F = A x P x Cd x Kz x Gh, where A is the projected area, P is wind pressure, Cd is the drag coefficient (ballistic chart info), Kz is the exposure coefficient, and Gh is the gust response factor.” 

What is a Mirage in Shooting?

A mirage is a distorted image seen from a distance. The most common mirage people think of is a shimmering on the horizon. It looks like water, but it is not.

In shooting terms, a mirage causes your target to look like it is moving like a wave. Mirage can be caused by wind and by heat. Heat-caused mirages are also air-based because the heat rises, moves the air and distorts your view of what you are looking at.

The direction of these waves is important because this tells you the approximate wind speed.

Now, let’s take a closer look at types of mirages.

1. Boil

A boil mirage is where the waves are straight up and down. This means you have little to no horizontal wind between you and the target. You do not need to make windage adjustments for the wind in this case.

2. Slow

A slow mirage means the waves are moving at a slight angle. As the mirage angle moves from vertical to horizontal, the wind speed increases. A 30-degree angle means the wind is blowing around 3 miles an hour.

A 30-degree angle is around the 11 o’clock position if the mirage rises right to left. The wind is from the right.

If the mirage is in the 3 o’clock position or rising to the right, the wind is left to right. A 3 MPH win may require a minor windage adjustment. As the distance to the target increases, you have to increase your windage adjustment.

3. Medium

With a medium mirage, the wind is blowings 4-7 MPH. The angle is around 60 degrees. This is the 10 o’clock or 2 o’clock position.

If the mirage rises to the left at the 10 o’clock position, the wind is right to left. If it is in the 2 o’clock position, the wind is left to right

Bullets with a low ballistic coefficient start having real problems here. As the distance increases, this gets worse.

4. Fast

If the mirage is horizontal, the wind is at least 8 MPH and could be more. That is a 90-degree angle or the 9 o’clock or 3 o’clock position. At the 9 o’clock, the wind is right to left. At 3 o’clock, the wind is left to right.

All bullets will now have windage issues. As the distance increases, these windage issues will get worse.

Wind and Shooting

A lot of people use wind speed monitors to gauge the wind. These work but only at the exact location where the monitor is standing.

At the 50 Caliber World Championships at the NRA’s Whittington Center, I saw one competitor with a wind speed monitor. I also watched the wind socks every 100 yards down to the 1,000-yard targets. Some flags were completely flat. Some were flying at an angle. This happened at the same time over that 1,000-yard distance.

If the shooter’s wind speed monitor was still, but a flag at the 500-yard line was flapping, his device was useless for plotting his shot.

This is why a spotting scope is better. You can judge the maximum wind speed by checking the angle of the mirage. Wind socks and a spotting scope are the best combination.

Now, let’s look more closely at the factors that are affected by wind when shooting.

1. Distortion

Distortion is how much the image you see is twisted or wavy. The amount of distortion is irrelevant. You are worried about the angle, because the angle tells you the wind speed.

Distortion could be mild or severe. Keep a close eye on the angle. You may see a lot of distortion but have an 11 o’clock angle, which means the wind is mild.  If you have just a little distortion, but a 9 o’clock angle, you have a lot of wind.

2. Bullet Coefficient 

Bullet manufacturers publish coefficient tables on their websites. Look up your bullet on the maker’s website to get this information. 

Coefficient is how well the projectile bucks the wind, how straight it shoots in other words. Some bullets are terrible and wind pushes them all over the place. Some are good and wind affects them less.

Wind is always going to affect a bullet. As the target gets farther and farther away, the wind deflection will be worse. At extreme long ranges, a bullet’s wind deflection can be several yards. 

SPOTTING SCOPES

Several optics companies make spotting scopes. If you are looking to buy one, here are the important parts:

1. Mount

It needs to attach to a tripod through a mounting point. The scope needs a stable platform for ideal performance.

2. Magnification

More magnification is good. The drawback is higher magnification means the image quality drops. 

3. Glass

Quality glass in the scope gives you the best possible image looking down range.

4. Case

A spotting scope is big and can be expensive. A good carrying case is essential to protect this investment.

Suggested Spotting Scopes

Editor’s pick – Vortex Viper

Specifications

• 4 models to choose from
• Extra-low dispersion (ED) glass
• External lenses protective coat
• Waterproof
• Detachable eyepiece
• Mounts to a standard camera tripod
• Fine and fast focus dials
• Lifetime warranty
• No carrying case

Mid-range – Celestron Ultima 80

Specifications

• Coated lenses
• Lifetime US warranty
• Carry case
• Separate case for eyepiece
• Tripod mount plate
• Waterproof

Best budget – Bushnell 20-60×65 Trophy Xtreme Spotting Scope

Specifications

• Waterproof
• Standard tripod mount
• Tabletop/window mount tripod included
• Porro prism (clear picture)
• Coated lenses
• Soft carry case
• Hard carry case

FAQS

Conclusion

Learning how to use a spotting scope will make you a better shot at long and extreme long range shooting. It will take practice under varying wind conditions to learn how to use the scope.

You also need to know your bullet’s performance under various wind conditions.

If your hunting is a maximum of 300 yards, a spotting scope is not necessary for gauging mirage and wind conditions unless you are shooting bullets with speeds under 1,500 feet per second.  

If you shoot tournaments, a spotting scope will help you even shooting at 100 yards.