Wind Force

Beaufort	scale of the wind	effects	m/s	Km/h
0	calm	none	0 - 0,5	0 - 1
1	very slight draft	smoke does not rise up straight	0,5 - 1,5	1 - 5
2	very light breeze	just perceptable	1,5 - 3	6 - 11
3	light breeze	leaves move	3 - 5	12 - 19
4	moderate breeze	small twigs move	5 - 8	20 - 28
5	fresh breeze	larger twigs move	8 - 10,5	29 - 38
6	strong wind	larger branches move	10,5 - 14	39 - 49
7	stiff wind	weaker tree trunks move	14 - 17	50 - 61
8	stormy wind	stronger tree trunks move	17 - 20,5	62 - 74
9	storm	roof tiles are taken off	20,5 - 24,5	75 - 88
10	strong storm	trees are uprooted	24,5 - 28,5	89 - 102

This is an excerpt from "The New Boomerang Booklet", which the author kindly put to our disposal. For further and very detailed information on the topic of boomerangs and also on this subject, see "The new Boomerang Booklet" by Michael Siems.