Posted: Tue Jan 21, 2003 11:27 pm
The other thing that is important to think about when interpreting these types of graphs is that they are for the average wind speed as a function of height. Averaged over some period of time longer then the turbulence time scale. The type of flow they describe is turbulent flow over a rough boundary.
For kiting it is important to remember that the instanteous variation of velocity with height may not look anything like these graphs. Turbulence is often descibed as sweeps of fast air moving down from above, during which the velocity at your 2m wind meter may be close to the velocity higher up , and then ejections of slow parcels of air from close to the boundary up into the higher flow. Under the right condtions it can average to something like those graphs, but your kite pretty much feels the instantaneous wind with a pretty fast reaction time. So if you want to be safe with your wind meter look at the gusts and base it on that. But still relying soley on a wind meter is probably a bad idea and you should use your experience tell you what kite to rig based on many factors..
For kiting it is important to remember that the instanteous variation of velocity with height may not look anything like these graphs. Turbulence is often descibed as sweeps of fast air moving down from above, during which the velocity at your 2m wind meter may be close to the velocity higher up , and then ejections of slow parcels of air from close to the boundary up into the higher flow. Under the right condtions it can average to something like those graphs, but your kite pretty much feels the instantaneous wind with a pretty fast reaction time. So if you want to be safe with your wind meter look at the gusts and base it on that. But still relying soley on a wind meter is probably a bad idea and you should use your experience tell you what kite to rig based on many factors..