It is amazing how we sometimes can ride in 6 knots of wind (measured at 10 m height), and other times even 8 knots does not work.
"Cheese Wind" as I call it, micro bubbles/turbulence so small it can not be felt as gusty wind, it is just "powerless" wind, for the given wind strength
This is why, apart from measuring on the beach which sometimes gives an ok reading, at other spots rubbish, there are SO many different numbers for low end posted, which can not be compared.
But even if wind has same speed at kite height and same density, the pull is not always the same because of micro turbulence is my claim.
Amazing how low you can go Regis