Aeronautical Information Manual (AIM), page 591

Index   590 -- Page 591 -- 592

12/10/15                                                                                                            AIM

                                                       TBL 10-2-3
                              Table of Common References for Estimating Wind Velocity

    Wind             Wind                                     Appearance of Wind Effects
   (Knots)       Classification                 On the Water                                  On Land
Less than 1    Calm                Sea surface smooth and mirror-like         Calm, smoke rises vertically
1-3            Light Air           Scaly ripples, no foam crests              Smoke drift indicates wind direction,
                                                                              wind vanes are still
4-6            Light Breeze        Small wavelets, crests glassy, no          Wind felt on face, leaves rustle, vanes
                                   breaking                                   begin to move
7-10           Gentle Breeze       Large wavelets, crests begin to break,     Leaves and small twigs constantly
                                   scattered whitecaps                        moving, light flags extended
11-16          Moderate Breeze     Small waves 1-4 ft. becoming longer,       Dust, leaves, and loose paper lifted,
                                   numerous whitecaps                         small tree branches move
17-21          Fresh Breeze        Moderate waves 4-8 ft. taking longer       Small trees in leaf begin to sway
                                   form, many whitecaps, some spray
22-27          Strong Breeze       Larger waves 8-13 ft., whitecaps           Larger tree branches moving, whistling
                                   common, more spray                         in wires
28-33          Near Gale           Sea heaps up, waves 13-20 ft., white       Whole trees moving, resistance felt
                                   foam streaks off breakers                  walking against wind
34-40          Gale                Moderately high (13-20 ft.) waves of       Whole trees in motion, resistance felt
                                   greater length, edges of crests begin to   walking against wind
                                   break into spindrift, foam blown in
41-47          Strong Gale         High waves (20 ft.), sea begins to roll,   Slight structural damage occurs, slate
                                   dense streaks of foam, spray may reduce    blows off roofs
48-55          Storm               Very high waves (20-30 ft.) with           Seldom experienced on land, trees
                                   overhanging crests, sea white with         broken or uprooted, "considerable
                                   densely blown foam, heavy rolling,         structural damage"
                                   lowered visibility
56-63          Violent Storm       Exceptionally high (30-45 ft.) waves,
                                   foam patches cover sea, visibility more
64+            Hurricane           Air filled with foam, waves over 45 ft.,
                                   sea completely white with driving spray,
                                   visibility greatly reduced

Wind from the South-East, estimated speed 15 knots. Wind shifted from North-East about fifteen minutes ago, and is gusty.

Special Operations                                                                                              10-2-13

Page 591 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   590 -- Page 591 -- 592