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  • Reading the wind

    Hey Folks,

    I wanted to post a thread for those of you that have trained here at CVT and for the ones that can't make it. This will be a review of wind reading basics. First thing is our formula: Inches X wind speed / by 1 minute of our distance. We have to have a range card that breaks our wind down to 1 mph. So that it shows us how many inches our bullet will move for every 1 mph of wind speed. Here's link to a ballistic chart you can use. You can fill in the blanks but be sure to only use 1 mph of wind speed rather than 10 mph.http://www.eskimo.com/~jbm/calculations/tr.../traj_card.html

    Now it should look something like this:



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    Now the one on the left is for 40 degrees and under. The one on right is any over 70 degrees. Remember these are just a starting place. Now notice the column that reads 1 mph wind. Now scroll down to 600 yards. Both cards say at 600 yards your bullet will move 3" (inches) for every 1 mph of wind speed. So if we have a wind speed of 5 mph all we do is multiply 3" x 5 mph= 15" So now we know our bullet will move 15 inches in a 5 mile per hour wind at 600 yards. Now we need to change this to moa so we can dial it in our scope. So we now need to divide our 15 inches by 1 minute of angle of our distance. Which 6" in 1 moa of 600 yards. Right? So 15"/ by 6= 2.5 moa. Now we dial 2.5 moa of wind in our scope depending on which direction it is and we are ready to shoot. Now we must always figure our wind as a full wind (either 3 to 9 or 9 to 3 o'clock) first. Then if our wind is a different direction we simply look at our rosette and multiply our formula by the cosign. Here's the rosette:


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    Now for an example we had a 5 mph wind at 600 yards and for a full wind we dialed 2.5 moa in our scope. Now lets say our wind was coming from 1:30 o'clock. We look at our rosette and the cosign is .707. Now just multiply 2.5 X .707= 1.7675 which is 1.75 moa which is 70% of a full wind value. So with a small plastic oil bottle, we fill it with baking powder and by pointing at our target and squeezing it we can tell exactly what direction the wind is coming from.

    Now, first and for most we need to be able to read our natural wind indicators. Shocker!!!! Boys and girls there are no wind flags on the battle field. With that said we need to be able to read our indicators. Here is a good list EShell a great student and friend of mine put together: C.V.T. Wind Indicators

    Tactile and Visual Indicators
    • 0-1 MPH Wind imperceptible.
    • No grass or leaf movement.
    • Smoke rises straight up.
    • Mirage runs vertical.
    • 1-2 MPH Cooling effect of wind may be noticed.
    • Light movement of grasses.
    • Only a few leaves on any given tree in motion.
    • Mirage begins to lean to 12:30.
    • 3 MPH Wind pressure can be felt on bare arms.
    • Grasses obviously in motion.
    • All leaves on any given tree in light motion.
    • Mirage leans to 1:00-1:30.
    • 4 MPH Wind pressure can be felt on face.
    • Small twigs bearing leaf clusters begin light motion.
    • Mirage leans to 1:30-2:00.
    • 5 MPH Tips of smaller branches begin motion that hold the leaf limbs.
    • Mirage leans to 2:00-2:15.
    • 6 MPH The trunk branches start to move. These are the heavy limbs holding the smaller branches.
    • Mirage leans to 2:15-2:30.
    • 7 MPH Larger (trunk) limbs begin motion.
    • Young (softer) leaves begin to flip over on windy side of trees.
    • Mirage leans to 2:30.
    • 8 MPH Tree tops are in light motion.
    • Mature leaves flip over on windy side of trees.
    • Mirage leans to 2:45.
    • 9 MPH Tree tops show obvious movement.
    • Almost all leaves flip over.
    • Mirage leans to 2:45-3:00 and begins to run.
    • 10 MPH Wind pressure can be felt against the body.
    • Tree tops show substantial movement.
    • Mirage runs slowly and parallel to ground.
    • 11 MPH Mirage runs quickly along the ground, begins to break up.
    • 12 MPH Wind pressure can be felt against the body.
    • Mirage runs very quickly in sheltered places, mostly broken up in exposed areas.
    • 12-15 MPH Dust is raised.
    • Lighter debris moves around.
    • Mirage blows off completely in exposed areas.
    • 15-20 MPH Dust clouds blow around.
    • Debris blows around.
    • Smaller tree trunks sway.
    • Major limbs on larger trees in constant motion.
    • 20+ MPH Difficulty walking.
    • Larger tree trunks sway.


    Now if we can learn to read our natural wind indicators at our muzzle, mid-range and at our target, we simply aggregate the speeds together as one. Example: at our muzzle the leaves on the bushes are all in motion=3 mph, mid-range they are in motion but the small limbs that hold the leaves are moving as well= 4 mph. At our target the wind is the same as mid-range=4 mph. So we call this a 3.6 mph wind. We added all the wind speeds and divide them by 3 (our muzzle=1 our mid-range=2 our target=3).

    Now a good tool is the Kestrel 4000, not only will it read wind very accurately but it will give you temp, baro, humidity, altitude and density altitude. I want you to use this only to confirm your wind speed. You really need to able to read the wind by what you see and feel. NOW ONLY USE MIRAGE TO READ WIND DIRECTION. Why? Because wind speed can be very high but because of terrain it can be deflected and look like it's much slower.

    With our plastic oiler bottle we can determine wind direction at the muzzle. Mid-range and at the target we will need to follow the direction of the mirage until it starts to boil. Example: If the mirage is flowing from left to right then follow it to the left until you see it boil straight up. This is the direction the wind is blowing from. If you use your spotting scope next to you, follow it until it boils then look at the target in relation to the spotting scope and this will tell you if it's 1 o'clock or whatever. Think of yourself sitting in the middle of the clock and the target always being 12 o'clock.

    Lets review for a minute. Once we know our range of our target we find out how many inches our bullet will move for each mph. Then by using our natural wind indicators we determine our wind speed. Using our plastic bottle we determine our direction at the muzzle. With the spotting scope we determine wind speed and direction at mid-range and our target. We then take our inches X our mph= inch value now divide that by 1 moa of our distance and we have our moa wind value. If it's a full wind we can dial this into our scope, if not we determine our direction and apply our rosette cosign.

    This is not something you will master in three or four days. It will take much practice. However, as EShell will tell you it works. I think all of the students here at CVT will tell it works real well. Wind drift is over 120 years old. It was used by Artillery folks for many years, as well as our Military marksmen. It wasn't until the mid sixties it fell to the wayside.

    Congrats to Marc and Ed for winning and placing in the top five at the ASC match recently. You and the young folks did a great job. I'm very proud of each of you.

    This is very hard to put on paper. Being able to show you what the leaves and trees are doing is pretty easy however, writing it is tough. I hope this review has help you and bring to mind some of what I've taught you. Like I've always said just because your not here doesn't mean the training has stopped. If you have questions you can always call.

    God Bless America, flea



    If you would like to book training with Vern Harrison and Central Virginia Tactical, please see his contact information. It is worth every penny.

    --nate
    Last edited by nate; 01-03-2015, 04:32 PM.
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      nate
      Hey Folks,

      I wanted to post a thread for those of you that have trained here at CVT and for the ones that can't make it. This will be a review of wind reading basics. First thing is our formula: Inches X wind speed / by 1 minute of our distance. We have to have a range card that breaks our wind down to 1 mph. So that it shows us how many inches our bullet will move for every 1 mph of wind speed. Here's link to a ballistic chart you can use. You can fill in the blanks but be sure to only use 1 mph of wind speed rather than 10 mph.http://www.eskimo.com/~jbm/calculations/tr.../traj_card.html

      Now it should look something like this:




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      01-03-2015, 04:30 PM
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