Out in the Elements: Military Sniper
A blog series detailing impacts the weather has on a variety of professions.
Many of us have nice jobs in nice buildings in nice places. But not everyone. There is a large segment of the population that consists of hands-on, outdoors, all-weather professionals. These guys don’t get snow days. Some are obvious: take for example the farmer whose very livelihood is tied to the earth in the purest sense. Others are less so: The railroad engineer who finds himself traveling a one-way route through a hail core.
For this series, I wanted to explore just how the weather and by extension the environment affects a variety of workers. Pop culture has examined everything from the jobs that make you wealthy to the jobs that make you filthy. I think it’s time we honor some more of our hard workers. The ones that find themselves out in the elements.
The military sniper is perhaps one of the hardest jobs on the planet. Picture this: you are told you will be going to a place where almost everyone will want you dead. Great. You are told you will be alone; if you are lucky there will be one other with you. Even better. You are told you will be there at least 3 days, possibly longer. Couldn’t be happier. You are told you will be required to remain perfectly still for almost the entire duration. Sounds easy enough. You are told that if you fail to make your shot from a distance greater than several football fields, you very well could die. Alright. And finally, you are told you will be required to perform with the wind blowing, rain falling, and a temperature around freezing. Sign me up!
Oh, and I almost forgot. In addition to everyone there wanting to kill you and your allies, they particularly hate snipers.
Snipers really do perform a duty that most others are simply not cut out for. I know I’m not! But how do they do it? Sure, a very high degree of mental fortitude, proper training, and a desire to fight for their country are certainly prerequisites, but what’s the science of survival? How do these men and women cope when they are out in the elements?
I had an opportunity to interview an army marksman, and some of what I found out was beyond any of my expectations. He has requested anonymity. Here’s what I learned!
The military marksman, also called a sniper, faces many environmental obstacles. Of primary concern is wind, precipitation, changes in pressure, and ambient temperature.
Wind poses a very significant challenge to a sniper. I was told that if not corrected for, the wind could push a bullet off target by more than a foot at relatively short distances! According to the Physics department of the University of Utah (http://www.physics.utah.edu/~mishch/wind_drift.pdf) The distance a bullet moves when impacted by wind can be estimated as :
While the math may seem daunting, it’s still just estimation! It basically means that the distance a bullet moves left or right (∆x) is equal to how strong the wind is blowing divided by how fast the bullet is moving (Uwind/U0) multiplied by the density of the air (ρ) multiplied by the cross-sectional area, or the portion of the bullet that is being hit by wind (A˔) multiplied by the distance the shot was fired squared (L^2) divided by the mass of the bullet (m) and multiplied by a drag factor (C/4).
Okay, now that everyone has a headache, let’s put that into perspective. For the University of Utah’s experiment, a bullet drift of 6cm was calculated with winds at 20 miles per hour. Over a distance of only 50 meters! Imagine the drift if we tried to make that shot over a mile away! So what can a sniper do to compensate for that?
To start, they use very high velocity and very heavy rounds. This reduces the amount of time the wind has to act on the bullet as well as increased the bullets mass. As you can see, these two factors (m and u0) are on the bottom portion of the equation. That means as these numbers get bigger, the movement (∆x) gets smaller! Similarly, if the equation was y=1/x where x gets bigger and bigger, y gets smaller and smaller! Y=1/2, Y=1/3, Y=1/4 and so on.
These military folks are pretty smart! By using very high velocities and heavy rounds, they are setting themselves up for success before they even leave for the field!
With ammunition that is designed specifically for the job, what else could possibly affect a sniper? Despite having lessened the impacts of wind, a sniper must still adjust for it. At long distances, even a heavy fast moving bullet drift some in the wind. To account for this, the sniper uses a number of techniques to account for wind speed
A sniper can watch how heat near the ground distorts the light. In a calm wind, these distortions are mostly vertical. As the winds increase, these distortions can appear to bend over. By noting how much the mirages are tilting over, a sniper can discern an estimated wind speed.
In many desert climates like the Middle East, a sniper can use dust and other small windblown debris to determine wind speed and direction.
In an active battle arena or an urban area, smoke is often widespread. This can be used in the same way as dust or natural debris to determine information about wind.
For a sniper, it is also important to remember that the wind closest to him is the most important. A small deflection in the trajectory early on can make much larger errors down range where as a small bump near the target remains a small error.
As you can see, if you bump the bullet early, huge errors occur later. But if you bump the bullet late, only a small movement can occur and a hit on the target can still be made.
Aside from wind, the other major impacts include precipitation, temperature, and changes in pressure. While precipitation and temperature can have degrees of impact on the physics of a shot, the primary issue these factors cause are to the human shooter, the sniper himself. According to the University of Maryland, (http://umm.edu/health/medical/altmed/condition/frostbite) hypothermia occurs when the body temperature falls to 98 degrees Fahrenheit, just 0.6 degrees below normal. In addition, in very cold weather frostbite can occur within minutes. Sniper’s adapt to this in a variety of ways, including dressing appropriately and through intense training to be able to withstand the cold and the heat.
Precipitation poses similar issues. When you are wet, water begins to evaporate off of your body. As this happens, a phase change in the water occurs as it goes from a liquid to a gas. This causes the water to sap extra heat energy from the environment, in this case the poor soaked sniper. Acting much like an abundance of unnecessary sweat, this can quickly lead to hypothermia even when the ambient temperatures are quite warm. Add to that the reduction in visibility of the target, and precipitation can become a huge problem for a sniper. Little can be done to stop the rain, and a sniper must rely on his training and proper attire to endure. Whoever it was that said “a little rain never hurt anyone” clearly was not a sniper!
Perhaps one of the most interesting aspects of the environment affecting a sniper is that changes in atmospheric pressure must be taken into account. As a sniper travels from place to place and his elevation changes, this affects the barometric pressure. Since pressure is directly related to density, this subsequently affects how much the wind is able to push a bullet. As you will recall from where we looked at the equation for how much wind pushes a bullet, the density (ρ) was a factor. The higher the density, the more the air can push. As an example, let’s imagine we are outside and the wind is blowing around 40 mph. It’s quite gusty but most of us can get out and about without much issue. Air isn’t very dense. So here we are, walking around in the wind and we get hit by a bus, which just so happens to be driving at 40 mph. A bus is VERY dense.
At sea level, the pressure is a bit over 1013 millibars on average. One mile up, say in Denver, the average pressure is in the neighborhood of 830 millibars. Utilizing the ideal gas law (Ugh, more math), we can say that ρ=P/RT. That means that density is equal to pressure multiplied by “R” multiplied by temperature. R is just a number that doesn’t change, we call it the gas constant and it can usually be approximated as 287 J/KG. If we assume that the temperature doesn’t change from our flight from Miami (near sea level) to Denver (one mile up) and stays 68 F (20C) the only change is the pressure. In Miami, the density would be about 1.2 kg/m^3. In Denver, the density would drop to about 0.99 kg/m^3. That means the density has dropped about 17%, which would mean that the bullet would be pushed a considerable amount less in Denver. This would also apply if the sniper is shooting at a high angle and not just travelling to a higher place: as the bullet changes elevation the density changes and this must be accounted for before the shot is made.
For those of you confused (I know I am..) it works like this: the higher you go, the less wind matters. So for a sniper shooting upward or travelling to a place with a higher elevation, he must remember to not adjust so much for wind. The same applies in the other direction: if a sniper goes from a higher place to a lower place, he must remember that the wind will have a larger effect.
Being out in the elements for a sniper isn’t easy, but with a little knowledge of physics and a whole heap of training, some pretty miraculous results can be had. Pretty neat stuff.
Next time, we’ll look at some of the myths and lesser effects that the environment has on a sniper. Beyond that, we’ll take a look at more jobs out in the elements. Feel free to message myself or Zach Roberts with requests. Think your job is tough? Let us know!