As above, the Windtronic 2 is the better offer on the market. I don't own one, but I have looked into the purchase in the past. This is the critter from one of the sponsors web sites
http://www.kitepower.com.au/catalog/product_16505_Windtronic_2_Windmeter_cat_323.html They have a threaded socket on the base, for pole or tripod mounting, so you could potentially raise it above the crappy ground wind/turbulence to get a more accurate measurement of what's there... or, you could just look at the environmental effects and rig your kite accordingly.
Google "beaufort scale" or go here
en.wikipedia.org/wiki/Beaufort_scale PS. my personal favourite is "Beaufort 6"