Thread: Acceptable group size at long range ?

Tussock I have no idea what m/sec is so looked it up and found out that 3 m/sec = 6.7mph

I also found this
Beaufort Wind Scale Windspeed
in MPH Description - Visible Condition

0 Calm smoke rises vertically
1 - 4 Light air direction of wind shown by smoke but not by wind vanes
4 - 7 Light breeze wind felt on face; leaves rustle; ordinary wind vane moved by wind
8 - 12 Gentle breeze leaves and small twigs in constant motion; wind extends light flag
13 - 18 Moderate breeze raises dust and loose paper; small branches are moved
19 - 24 Fresh breeze small trees in leaf begin to sway; crested wavelets form on inland water
25 - 31 Strong breeze large branches in motion; telephone wires whistle; umbrellas used with difficulty
32 - 38 Moderate gale whole trees in motion; inconvenience in walking against wind
39 - 46 Fresh gale breaks twigs off trees; generally impedes progress
47 - 54 Strong gale slight structural damage occurs; chimney pots and slates removed
55 - 63 Whole gale trees uprooted; considerable structural damage occurs
64 - 72 Storm very rarely experienced; accompanied by widespread damage
73+ Hurricane devastation occurs