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I'm impressed, Keith. Lots of information. However, is BP right or wrong? Here's what he wrote:
"As long as this big globe we are all on continues to rotate, there will be drag of the atmosphere's lower boundary layer with the terrain that creates turbulence ... and wind."

John I agree with you what it's doing at one elevation may not be doing at another, one side of the range or the other. At the firing line or at the target.. It not only changing but hard to read without instruments.

Years ago I worked for the Coast Survey, one of the things we did was establish and read tide and current meters.  Water level could be falling while the tide was coming in. Moving in on the surface while out down deeper was the culprit.  Once things got going with some velolicty current settled down to fairly consistent. Around the time of the change from high to low or low to high was the most inconstant

Wind is the same way, get a defined system strong one direction it's much more predictable than when one system is dying off and another coming in. 

I always look at the weather reports day before a match & make observations while shooting. Next day compare my observations with the official government reports near as possible to the range.  Data is wonderful today easy to access and accurate.  Gives you feedback on the accuracy of your observations. 

Still best way to see what the effect of wind is, bullet on the sighter target. Nothing is as accurate as actual shots falling

Boats

There are a number of mathematical tools to estimate wind speed at different elevations if you know the wind speed at a reference elevation.

The following graph was lifted from a triathlon forum and shows wind speed vs. elevation for a reference wind speed of 20 mph at 10 meters. 

The graph stops at one meter elevation - which is the important elevation for bicyclists and isn't far off from the height of a normal wind indicator.

The curve can be easily extended for greater elevations and, if extended, would show that the wind speed at the path of bullet is greater than the indicated wind speed at the height of the indicator.   

Nonetheless, the fact that wind speed at the indicator is less than wind speed at the bullet's path does not invalidate the indicator readings because we take sighters to determine proper hold-off based on the indicator rather than actual wind speed.

What the graph does tell us is that the effect of wind on the projectile's flight is likely greater than we would assume from the indicator (or from a wind gauge reading at the same height as the indicator).

So, just because an indicator is not moving, it doesn't necessary follow that the air isn't moving in the bullet's path.

JackHughs

If anyone has obtained aviation weather for a particular airfield, they know that winds at the surface vary in direction and magnitude from the winds aloft, and winds aloft vary at differing elevations, with mixing between layers.
The jet stream is called a stream for good reason, and weather uses many of the same descriptors such as troughs, ridges, depressions, etc, just as landforms (both continental and oceanic) have troughs, ridges, depressions, etc, which affect the flow of the respective overlying fluids.
As Boats mentioned, distant conditions affect local conditions.
Winds aloft over two distant airfields may be quite similar, but winds at the surface may be different because of the respective local terrain conditions.
Airfoils are considered to be relatively smooth surfaces (excluding rivets, stitching, taping, other imperfections, etc) but depending on the amount of camber (curvature) of the upper and lower surfaces (which often differ), for given velocities, flow over the surfaces may be laminar, or (as airspeed and angle of attack change) flow may separate from the surfaces creating turbulence, vortices, drag.
Local landforms vary in the amount of curvature and surface roughness, height, orientation to oncoming wind, angle of slopes, etc, which affect localized airflow.
Surface roughness will vary by vegetation type as well.
I'd love to see joeb post a simple list of all the variables that affect airflow, before the variables were entered into any spreadsheet.

joeb wrote Quote:

joeb,
Don’t those tunnels have ventilation?
Doesn’t ventilation require airflow?
Have you ever considered taking a geomorphology class, and maybe an aviation weather class too?

Tim maybe I wasn't clear in that I was talking about learning how to shoot the various conditions.

JLouis

JLouis wrote on Feb 28^th, 2014 at 5:38pm:


Well, if today was the first you've heard of thermals, as in another condition, you've got more learning to do.
The point, which you may have missed, is that it's another condition.
When present, often, the wind becomes your friend.

Frank I did not mention lighting as the subject was wind but now that you have mentioned a novice shooter could interpret an off shot due to lighting as a miss read in wind should he or she not know the differance. You are somewhat correct when visiting a new range as a good doper can quickly get a handle on it during practice. The exception being the Gremlins living in the creek at Emerald Empire in Springfield Oregon that reach up and flick your bullets as they pass by. The home range competitors  that I shot the CBA Nationals with were saying that even they cannot get a handle on that.

JLouis