Analyzing wind drift with trigonometry explained.

[BillyGoatCrawler]

So wind drift and the trigonometry behind it can be confusing for shooters that do not have a math background. I put this together to help depict the math behind the physics of wind drift. I put this together because when to use sin or cos can be confusing if you do not understand what is going on. Many people hear of cosine and think it should be used indiscriminately. But, using the incorrect trigonometric function will yield an incorrect result.

This is simply the physics of wind and vector components. In real life your projectile will most likely not experience one simple and steady wind on its path to the target. It will most likely experience a few vectors, so this is not an exact science all the way to impact, but this can clarify how wind angles truly affect a projectile.


The purpose of this to help new and interested shooters understand the subject, math, and the physics of wind drift. It is not a cure all approach to making a wind call, as a range will have many varying winds on the path down range.


Basically think of viewing yourself, the target, and the wind as a right triangle, as viewed from above. Remember back to the Pythagorean theorem and that a^2 + b^2 = c^2 (^2 means "squared")
Trigonometry uses angles to determine one of these components based off an angle within the triangle. In our case the angle will be in reference to the wind direction.

Now, think of that triangle being superimposed on a Cartesian coordinate system(x, y graph). Wind can be broken down into unit vectors. What this means is that the wind value affecting the x component can be calculated as well as the y component. Since only one of these values affect lateral drift, we only need to treat wind in regards to that, since that is the component of the wind that will affect our projectile.

As they say, a picture is worth 1000 words. So, here is 2000 more words consolidated into some images. Again, the take away of what we are doing is vector anaylsis to find the component that affects drift experienced by wind since this is a different value than a measured wind at an angle.



Now, you're creating a simple equation to solve for the component that affects left and right drift. Sin=opposite/hypotenuse so plug in these numbers and solve for the desired side. Basic formula if you're measuring the wind at your position:

(wind experienced)sin(angle of wind)=(wind value for hold) Use this wind value for your true hold.


If you're referencing wind with respect to the target, use this method:

[BillyGoatCrawler]

Reserved.

[Delfuego]

...and the anti-gun establishment thinks that we (gun enthusiasts) collectively have a 6th grade education.

[kcstott]

...and the anti-gun establishment thinks that we (gun enthusiasts) collectively have a 6th grade education.

they got the numbers confused. it's an education to the sixth power, buy they can't perform scientific notation

[kcstott]

Standish

Not to criticize but you should draw the last vector correctly with regard to the correction in angles.

Some may not be familiar with trig and not know that all your angle need to add up to 180˚ meaning the angle opposite your 30˚ vector = 60˚ and there fore has more of the available wind acting on the bullet

With the triangles all the same in your example people may not see the increase

an other way to look at it is to use a sail boat tack angle calculator for those that want to envision it.

[BillyGoatCrawler]

Standish

Not to criticize but you should draw the last vector correctly with regard to the correction in angles.

Some may not be familiar with trig and not know that all your angle need to add up to 180˚ meaning the angle opposite your 30˚ vector = 60˚ and there fore has more of the available wind acting on the bullet

With the triangles all the same in your example people may not see the increase

an other way to look at it is to use a sail boat tack angle calculator for those that want to envision it.

I had thought of doing that. Using a 30/60/90 triangle throughout, but if I used 30 in the sin function and 60 in the cosine function they would have both equaled 5 and that might have been confusing. I wanted to illustrate the fact that the same angle at different vectors require different trig functions and will result in different holds.

If I used a 30/60/90 triangle and kept the angles the same throughout, we would work with all the same numbers and that would be even more confusing. I left out the complimentary angles to stream line the image by keeping angles that are not directly relevant out and to keep it less confusing for those who are not used to looking at more clutter.


Edit: Corrected vector error. Thanks for catching that. I made these quickly.

[kcstott]

the thing is I'm a 42 year old Toolmaker that hit trade school right out of High school and you should see the look on people face when you tell them that a 10 mph wind @ 45˚ is not half value it's .7 or .707% if you want to be that precise

if you want to see a grown man cock his head and wrinkle his lip tell him that.

just take that wind angle and look up the Sin x your wind speed and done.

[BillyGoatCrawler]

the thing is I'm a 42 year old Toolmaker that hit trade school right out of High school and you should see the look on people face when you tell them that a 10 mph wind @ 45˚ is not half value it's .7 or .707% if you want to be that precise

if you want to see a grown man cock his head and wrinkle his lip tell him that.

just take that wind angle and look up the Sin x your wind speed and done.

I know exactly what you mean. That is why I wanted to explain that this is actually dealing with vector analysis. It helps to explain why exactly we are getting approximately 70.7% of the perceived value of wind at a 45˚ angle. The math behind sin and cos, their opposite relations, and their parent graphs is very interesting. But the application is where the rubber meets the road.

As you said, just taking (windspeed)(sin(angle)) and done is easy if you're in a constant wind, I wanted to break it down so people could see what is happening with the whole representation.

Plus, if one is truly interested in shooting long range consistantly, then they are really just interested in physics. And this is a basic principle of physics. That may clear up some of the cos errors I see. I see lots of people using cos in place of where sin should be used. They're opposite functions.

In a right triangle, the sin of an angle is equal to the cos of it's complimentary angle.
sin30=cos60
sin45=cos45
sin60=cos30


Plus, the Long Range sub forum is lacking stickies. Maybe this one can be stickied to help answer common questions.

[kcstott]

Standish I think you did a great job. My mind works a little different then most, so yeah a visual aid is helpful, Me I've been doing trig for 25 years I can do the most common stuff in my head. But I've also used trig everyday on the job so it comes pretty easy for me.

Now if we got into Calculous Screw that. I'm done

[Ahhnother8]

I just came from Sac Valley off the 1,000 yard range. Wind reading is an art, not a science. The ONLY way to learn it is to do it over and over. Wind velocities and angles are not constant. Over each 100 yard segment of a 1,000 yard range, the wind can be doing something different. That is at least 10 different variations that affect the flight of the bullet. Sometimes the wind at one end of a range is blowing left to right and at the other end of the range it is just the opposite. Or the true wind is blowing in one direction and the apparent mirage is going the opposite way. The ONLY way to begin to learn about it is to shoot in it!!!!!!!!

[BillyGoatCrawler]

Analyzing wind drift with trigonometry explained.

I just came from Sac Valley off the 1,000 yard range. Wind reading is an art, not a science. The ONLY way to learn it is to do it over and over. Wind velocities and angles are not constant. Over each 100 yard segment of a 1,000 yard range, the wind can be doing something different. That is at least 10 different variations that affect the flight of the bullet. Sometimes the wind at one end of a range is blowing left to right and at the other end of the range it is just the opposite. Or the true wind is blowing in one direction and the apparent mirage is going the opposite way. The ONLY way to begin to learn about it is to shoot in it!!!!!!!!

While I mostly agree. I am trying to be productive and offer insight into the workings of LR shooting. Simply saying its an art and cannot be explained to any degree is not helpful. Many approach the topic with the clock system and judge full value and half value. Obviously that's even worse off.

[diver160651]

Analyzing wind drift with trigonometry explained.

Ops I miss read the title.. It wasn't about reading the wind, but the math behind the drift values. Good OP regardless

[kcstott]

I just came from Sac Valley off the 1,000 yard range. Wind reading is an art, not a science. The ONLY way to learn it is to do it over and over. Wind velocities and angles are not constant. Over each 100 yard segment of a 1,000 yard range, the wind can be doing something different. That is at least 10 different variations that affect the flight of the bullet. Sometimes the wind at one end of a range is blowing left to right and at the other end of the range it is just the opposite. Or the true wind is blowing in one direction and the apparent mirage is going the opposite way. The ONLY way to begin to learn about it is to shoot in it!!!!!!!!

Incorrect.

An Art is doing something that can't be Quantified, calculated, or measured. Wind speed even broken down to the minutest increment can be measured and factored in to the firing solution.

Now there are people out there that make it look easy and that to me is an art.

[Ahhnother8]

Incorrect.

An Art is doing something that can be Quantified, calculated, or measured. Wind speed even broken down to the minutest increment can be measured and factored in to the firing solution.

Now there are people out there that make it look easy and that to me is an art.

Wait!! I thought SCIENCE is applied to things that can be quantified, calculated, or measured. ART is more nebulous. Things that cannot be quantified, calculated, or measured and is in the eye of the beholder (windreader). I disagree that wind can be broken down to the minutest increment and measured and factored into a firing solution. A number of people have shown up at matches over the years with their wizzbang wind reader thingys, charts, graphs, and .30+ caliber Superloudenboomeners and still get their @$$ whipped by those who can actually read the wind.

We shoot with quite a few of the top long range shooters in the nation and it is rarely made to look easy. It always comes back to: the only way to learn it is to do it. We have hosted two advanced long range shooting clinics in the last two years. I post invites on this and other forums to come out and shoot, but most would rather not leave the safety of the keyboard.

A couple of people posting in the long range forum have been out to shoot and I would like to hear their interpretation of wind reading.

[BillyGoatCrawler]

Wait!! I thought SCIENCE is applied to things that can be quantified, calculated, or measured. ART is more nebulous. Things that cannot be quantified, calculated, or measured and is in the eye of the beholder (windreader). I disagree that wind can be broken down to the minutest increment and measured and factored into a firing solution. A number of people have shown up at matches over the years with their wizzbang wind reader thingys, charts, graphs, and .30+ caliber Superloudenboomeners and still get their @$$ whipped by those who can actually read the wind.

We shoot with quite a few of the top long range shooters in the nation and it is rarely made to look easy. It always comes back to: the only way to learn it is to do it. We have hosted two advanced long range shooting clinics in the last two years. I post invites on this and other forums to come out and shoot, but most would rather not leave the safety of the keyboard.

A couple of people posting in the long range forum have been out to shoot and I would like to hear their interpretation of wind reading.

Maybe there is a reason people don't want to shoot with you? Personally, I'd rather shoot in the national forest among friends than join the pissing contest that keeps popping up on these threads. If you want to post about your matches, make a thread. If you want to make a post about the art of wind reading, make a thread. If you want to discuss the math and trigonometry behind wind values at different angles then you're in the right place.