I have set a ten-mile per hour wind speed as my arbitrary wind effect-shooting environment. The reason is that in the evergreen forest of the West there are always a few bug kill or lighting killed trees around. I have a tendency of getting nervous when I hear large trees crash to the ground on a windy day. When the wind gets strong I try and find a safe location to set it out, or give up the hunt for the day. There is a reason they call dead limbs and tree tops Window Makers. I carry a chainsaw in my pickup to cut out trees that have fallen across the road.
I have notice that deer normally stop moving around on windy days unless there is rain or snow with the wind. And the weather is pushing them to a lower elevation.
But what got me on the subject was the effect of the wind on my bullet. Using the Sierra Bullets Infinity software I used the data collected from my Chrony, when firing a Savage 110, in 270 Winchester, with the Hornaday 140 grain BTSP at 3030 fps.
In this case I used a 10-mile per hour wind at 90 degrees to bullet travel.
100 yards = 0.97 inches of drift
200 yards = 3.97 inches of drift
300 yards = 9.47 inches of drift
400 yards = 16.68 inches of drift
500 yards = 26.76 inches of drift
I do not consider a ten-mile per hour wind a major factor at one hundred yards. I shake that much. But depending on the presentation of the target the shot gets a little more difficult at two hundred yards. At three hundred yards the drop of the bullet and the wind drift becomes a critical factor for the average hunter.
The last time I went out to practice for a couple of hours I was getting a strong north wind. The trees around me were swaying with the wind, and it was kicking up clouds of dust off a dirt road. I had placed some surveying flags down by my targets and the wind was lifting them. Competition shooters have wind flags and I assume that some of them are using a handheld anemometer. I have an older type, but I do not carry it with me when hunting. But on some days an anemometer is not helpful because the burst of wind comes in gust with high and low wind speed.
I have been known to toss a little dry dirt in the air, some pine needles or oak leaves to get the wind direction or a little spit on a finger. All scientific in nature.
But on that day the wind was a factor on the range. I was shooting three different rifles which normally shot good groups. But every shot would have taken a deer out to 200 yards. A side, behind the shoulder shot would have been do able at 300 yards, but a frontal shot at that distance on a small buck might place the bullet on the edge or outside the kill zone. A four hundred yard shot with the cross hairs centered on the front of a deer’s chest at 400 yards with 16.68 inches of drift, and 17.45 inches of drop would result in a miss.
At times I have taped a drop chart to the stock of my hunting rifle. Especially if I am hunting an area where a long shot might present itself. I believe that I will included wind drift data at ten miles per hour.
As a kid I learned about the Beaufort Wind Scale in Scouting. I believe that a hunter can use this system to his advantage. It is not as fool proof as plugging numbers into a computer program but it might help you manage bullet drift. I believe that people have a tendency to over estimate wind speed.
http://home.comcast.net/~garyt1/wind.htmlhttp://www.answers.com/topic/beaufort-scale?cat=technology&method=22