The origin of the question is the fact that many herbicide labels, which have the force of law, restrict application at more than a set windspeed, often 10 mph. If asked to tell what the windspeed is, many people will reference weather forecasters or weather reports, which most often use ASOS/AWOS readings which are usually based on anemometers 10m (about 33 feet) AGL.
However, the wind at 10m is not the wind at 1 meter, which is often the height of the spray boom and the place where the wind restriction on the label is applicable.
Here is a discussion of how to extrapolate wind speeds:
http://belfortinstrument.com/height-wind-measurements-ground/
The bottom line is the herbicide sprayer is probably perfectly safe to spray assuming a <10mph wind speed when ASOS reported winds are 13 knots or 15 mph at 10m.
Now back to airplanes. At what altitude or height AGL does an airplane respond to the listed crosswind component? Is it when the wheels touch the surface? If so, it seems likely that the real wind the airplane feels is less, perhaps considerably less, than what the ASOS is reporting.
I was looking for information on the height of the aircraft when the demonstrated crosswind info was applicable (is it at touchdown?) and was curious to see if there was any discussion in the aviation industry about the known difference between wind speeds at 10m and at the demonstrated crosswind altitude (whatever that is).
In addition to the Belfort post there used to be a post by Iowa State University which addressed the spread of odor from a hog confinement facility and talked about the same issue of wind speed at various AGL. I don't find it right. Probably new hogs don't smell.
