The wind value should be almost 71% instead of 50%.Ī 45° wind actually has a value of 70.7% of a full wind value, which is often rounded to 75% or referred to as ¾ wind value (see Table 1).Ī 30° wind actually has a value of 50.0% of a full wind value. So how much value do we give to a wind that is not blowing straight across our target?Īt first glance, a 45° wind angle would seem to exert half the sideways force on the bullet and half the force pushing with or against the bullet, so the bullet would be pushed half the distance in a 45° wind is it is in a 90° wind, but that is not correct. These are referred to as a full wind drift values. Most wind drift calculations are based on full cross winds (90°). ![]() Wind Angle Changes Amount of Bullet Drift Bullet Wind Drift Compared for 90° (left) and 45° (right) Angles. A single gust of wind that hits the bullet as it comes out of the barrel changes the angle of the bullet and it will continue traveling at that angle until it is acted upon by another gust of wind.įigure 1. To further complicate matters, both you and the game can be in protected areas with slower wind, but the wind is probably blowing much harder across the canyon between you and the target. Also, you may be in an area protected from the wind, but the target is in an area with more wind or vice versa. If you are shooting across a canyon, the wind is probably blowing up on the up-slope and down on the down-slope. Wind blowing across flat lands may be very smooth, like a slow moving flat bottomed section of stream, but winds blowing in the mountains are more likely to have swirls, upwellings, plunges and backwashes. Wind does the same thing as it moves across the land. Next time you have a chance to look at a creek or river, notice all the little eddies, swirls, upwellings and backwashes you see in the current and look to see if you can find what causes them. Wind has a tendency to blow parallel to the ground and is effected by hills, rock outcrops and trees. Most ballistics calculators assume a constant wind speed at 90°, but in mountainous terrain and in areas of mixed forests and open areas, it is rare to have both a constant wind and a perfect cross wind. We don’t care what the Beaufort Scale number is, we just want an accurate estimate of wind speed based upon the clues. ![]() Otherwise I suggest using a rangefinder to get an accurate distance, but learn to estimate wind speed using the wind conditions described in the old Beaufort Scale. If you have a trusted spotter, they can be responsible for reading the anemometer and range finder for you, while you get ready to take the shot. If you are in a concealed position, you may not be able to accurately measure the wind speed anyway. It also has to be carried in a way so you can find it and use it quickly, but you also have to keep it from banging against other gear while you are moving.Īn anemometer also requires hand movements to measure the wind speed, which may be a problem if you are not in a concealed position. Like a rangefinder, an anemometer is a valuable piece of equipment, but it is another piece of gear to carry. ![]() I’ve used hand held anemometers and am usually surprised by how hard the wind is blowing based upon my estimate. The most accurate method to measure the wind at the shooter’s location is with an anemometer. So, how can we improve our chances when shooting in the wind? Accurately Measure or Estimate Wind Speed If you are shooting at paper targets, there is not much at risk if you make a mistake, but when hunting, there is a lot at stake and I believe many misses and wounded animals are due to our failure to properly measure and adjust for the wind. ![]() In a previous post, I demonstrated the problem of wind drift when shooting at targets farther than 200 yards in the wind.
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