* Restricted Information: specialist Air Elementalists only

General Notes for Air Spells

  1. The effects of wind are as follows:
Random Wind Generation

Beaufort Scale

Windspeed (miles per hour)

Visual indicators

Effects
0 to 20%

0  Calm

0 mph

lake surfaces calm, trees still

 
21 to 40%

Generate wind direction randomly, biased for prevailing wind in locality.

1 to 3  Light

1 to 12 mph

surface drift of loose sand / dust / snow, Tangleweeds in motion, flags stirring

 
41 to 60%

4  Moderate

13 to 18 mph

Tangleweeds rolling, flags flying

 
61 to 70%

5  Fresh

19 to 24 mph

tree branches in motion

 
71 to 80%

6  Strong

25 to 31 mph

wavelets on lake surfaces

severe windchill in winter conditions
81 to 85%

7  Strong

32 to 38 mph

horizontal precipitation

risk of frost-nip on exposed flesh in winter conditions
86 to 90%

8  Gale

39 to 46 mph

spindrift on snow-covered mountaintops, dust clouds in desert

leaning into wind (forward speed halved)
91 to 94%

9  Severe Gale

47 to 54 mph

streams blown backwards, large trees in motion, trailing ropes blow horizontally

 
95 to 97%

10  Storm Force

55 to 63 mph

raised whirlwinds and plumes of snow on snow-covered mountaintops, dust storm in desert

buckled against wind (forward speed quartered)
98 to 99%

11  Severe Storm Force

64 to 72 mph

storm shroud of suspended spindrift on snow-covered mountaintops

extreme windchill in winter conditions: st @ BTS [windspeed -10]% (Co) vs d4 Cold Damage from frostbite on exposed flesh / Wind Walkers st @ BTS [windspeed -10]% (St) vs being ripped apart if holding hands
100%

12  Hurricane

≥ 73 mph

trees uprooted, structural damage to buildings, ships sunk, can form twisters

need to crawl against windspeed ≥ 80 mph, breathing difficult facing wind, st @ BTS [windspeed - 20]% (St) vs being blown off ground for d100 ft if windspeed ≥ 100 mph (see the Falling and Landing systems for the consequences)
  1. A wind can be considered as having a N/S and E/W component, which can be phrased as (a,b) where a is the speed from the North and b is the speed from the East. For example a wind speed of 25 mph from the North is (25,0). A wind speed of 25 mph from the East is (0,25). A wind speed of 25 mph from the South is (-25,0) and a wind speed of 25 mph from the West is (0,-25). A wind speed of 25 mph from due North East is (17.68,17.68) approx. The total wind speed w follows the rule that a2 + b2 = w2.
  2. To work out the combined wind speed when there is a natural wind and one or more Control Winds Effects, simply add the components. For example if the natural wind is 20 mph from the North (20,0) and Control Winds Effect of 50 mph from the South (-50,0) and another Control Winds Effect of 50 mph from the East (0,50), then the combined effect is (-30,50) or 58.3 mph (square root of 30 squared plus 50 squared) from the South East in the proportions shown. A feather floating in this wind will travel 30 miles West and 50 miles North in an hour, assuming that the Control Winds Effects and the natural wind remain constant throughout this period.
  3. Most Effects of Air Spells that produce a wind count as Control Winds Effects cumulating with each other in the above fashion, except where expressly stated otherwise.
  4. Wind Walk Effects cumulate with natural winds and Control Winds Effects in the above fashion.  However, the Wind Walkers are immune from the effects of the wind created by their Wind Walk.  For example if a 20 mph Wind Walk is being accelerated by a Control Winds in the same direction, the Control Winds can be increased to 64 mph (not 44 mph) before the Wind Walkers are at risk of being blown apart as above.

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