how-to-read-the-wind-2

How To Read the Wind – The Ultimate Guide – 2

In Blog by Rich4 Comments

Welcome to the second segment of our How to Read the Wind – The Ultimate Guide series at AccuracyTech! In this installment we’re going to discuss angles. The wind is always changing and depending on your angle in relation to the target and the wind, the effects of the wind will change as well. You have to be able to assess the conditions and how they affect your adjustments quickly so that you can make the shot before conditions change. We’re going to give newer shooters the tools to do that by discussing the different components of a firing solution in detail. Today, let’s dive into angles!

Wind Reading – Doping the Angle

There are two things that matter when wind reading and trying to actually dope the wind for the shot: the wind speed and the angle. Obviously the speed matters because the greater the wind speed, the more influence it has on your projectile while in flight. The angle also matters, in fact, it really matters more than speed. You could have a full 20mph wind blowing at your shooting position, but if it’s a steady tailwind that isn’t shifting, it will have zero effect on your shot for practical shooting. Even a 5mph wind blowing from a 90 degree angle will have a large effect over longer distances.

So, first thing is first. Either stand up at your shooting position, or as close to it as possible, and figure out what angle the wind is coming from. I turn my face until I feel the wind hitting it equally on the left and right sides of my face. Then I compare the angle the wind is coming from to the the direction of fire from my shooting position. The angle between the direction of fire and where the wind is coming from is what you want to get an idea of. This is where the wind clock diagrams come from.

wind clock

This is a typical wind clock diagram, pay attention to the terminology used, which is often incorrect!

Note that wind coming from approximately 45 degrees, or 1:30 and 11:30 on a clock, are notated as “half value” wind on the clock. That’s incorrect. A 45 Degree wind is actually closer to three quarter value wind. We wrote an article on proper wind call communication, if you haven’t read it, that article really applies here so please have a look at it. Also note that you are really only concerned with angles between 0 and 90 degrees. You don’t have to complicate it beyond that. The effect at 45 degrees is the same as the effect at 135 degrees, so keep it simple. Deal with angles between 0 and 90 degrees.

Wind Reading – Angles

Obviously, the angle of the wind is pretty significant. I’ve been stressing that since we started. You can get crazy and break those 90 degrees worth of angle down into all kinds of small increments. Again, keep it simple. The more complicated you make this, the longer it takes you to dope the wind and take a shot. The wind changes often, so you really need to embrace rules of thumb and shortcuts. You need to be able to ascertain the speed and angle, and make a wind call in seconds. The wind can change often, so pay attention to trends. What is the average speed? What angle is the wind coming from most of the time?

For the most part, you need only be concerned with a couple of angles. Wind coming from either directly in front or behind you is zero value. It does not affect the bullet’s flight path at all. Keep in mind this tends to be exceedingly rare. Head and Tail winds can also be extremely tricky. While it may seem to be coming from directly ahead, it need only shift a few degrees in either direction to move your projectile’s path. It can also change by a few degrees back across the zero degree angle mark and effectively change the direction the wind is coming from completely. If it’s a few degrees off to the left, after a small shift, it can be coming from the right, which would completely reverse the wind hold necessary for a hit. They’re tricky, watch head and tail winds carefully!

The opposite end of the spectrum is the full value wind angle. This is wind coming from your 90 degree angle, directly to your left or right. This has the most effect on your bullet’s flight path. It is also the angle I recommend you run your drop charts on. This way you have an excellent base line to dope your wind call from. If your 10mph, full value wind, adjustment at 500 yards is 1.0 Mils, that is an easy number to work with. You can halve the number if it’s only a 5mph wind. Likewise you can also adjust the effect based on an angle easier. Please note, you can’t multiply the 1mph full value wind by 10 to get the same effect, because the effect isn’t linear. Again, that’s why I suggest you start with the 10mph full value wind.

Between the no value and full value holds, at the 45 degree angle, you have a three quarter value wind. The reason it should be referred to as a three quarter value wind, not a half value wind, despite being exactly halfway between 90 degrees and 0 degrees again has to do with the wind’s effects. At 45 degrees the wind has a cosine value of around 0.707 which is a lot closer to 71% of the full value wind than 50%…hence the confusion and the emphasis on proper terminology!

millett-clock

Millett Scopes has a pretty simple clock diagram and it’s more accurate than the first example

You can further break the angle down into half value and quarter values in the same manner by halving and quartering the effects of the full value wind angle. Just remember that the real “half value” is more like halfway between the 0 and 45 degree angles than coming directly from the 45 degree angle. Same with the quarter value wind, it’s barely off to either side of zero. Once you get a feel for this and you start thinking of the 45 degree angle as three quarter value the rest of the angles and effects are easier to approximate and understand!

Wrapping Up

In the next installment of our How to Read the Wind – The Ultimate Guide series we’re going to be discussing wind speed. How to measure it, rules of thumb for determining wind speed without instruments, and how to incorporate that information into our firing solution. Remember you can get pretty fancy with angles and how specific you want to be, but in general, apply the KISS principle. Keep It Simple, Stupid! Split your wind clock into zero value, full value, and three quarter value winds. As you get better at it you might even be able to incorporate a true half value wind into your clock. Getting more specific than that probably isn’t necessary, and it certainly isn’t expedient. At some point the angle change becomes more hassle to split into small fractions than it’s really worth for the difference in the net effect of the angle change. This is a complex subject, so if you have questions, drop them in the comments below!

Owner and Proprietor of AccuracyTech, LLC. Rich is a Firearms Enthusiast, Precision Rifle Competitor, and Writer. He is committed to bringing readers quality reviews and articles related to the Precision Shooting Sports. If you have any questions for him, please use the contact form on the site.

Comments

  1. I wonder why you say that the effect of wind speed is not linear? Are you sure about that?

    1. Author

      “Please note, you can’t multiply the 1mph full value wind by 10 to get the same effect, because the effect isn’t linear.”

      Is that the part we’re talking about? Try it out. Run a firing solution for a 500yd shot with a 1mph wind at 0900. Then run it again for a 10mph wind at the same distance and angle. It won’t be an adjustment exactly 10x the amount of the 1mph shot.

      That’s why I say “the effect isn’t linear” The physical drift distance of the bullet is linear, but I’m talking about the difference in accuracy of using a 10mph solution and halving it versus a 1mph solution multiplied by 10. Make sense?

      Would, “the adjustments needed for the wind’s effects are not linear” sit with you better? The goal is clear information and I’ve rephrased things by request before.

  2. I was thinking that the reason the 1mph value doesn’t seem linear is because we usually have to round off the correction for a 1mph value. When rounding off the correction we loose some resolution.

    The converse would be to use the 10mph correction and divide it by 10 to come up with the 1mph correction. Is that result pretty close?

  3. It’s a lot closer, Todd, that’s why I suggest using 10mph for a good baseline. If you divide the 10mph corrections by 2, 10, whatever the end result is much closer to the real world result. Yeah the math would be easier for us to use the 1mph correction and just multiply it by the wind speed but it doesn’t work. You can try it in any ballistics software and see how far it’s off. I’ve had this debate a couple times now. I may dedicate an article to it in the future.

Have a question or comment? We want to hear it!