Tree leaves don't move, smoke rises vertically, sea is calm, mirror like.

Tree leaves don't move, smoke drifts slowly, direction of wind shown by smoke, not by vane, sea a light ripple.

Tree leaves rustle, flagswave slightly, vanes show wind direction, small wavelets or scale waves.

Leaves and twigs in constant motion, small flags extended, long unbreaking waves.

Small branches move, flags flap, waves with whitecaps.

Small trees sway, flags and ripple, moderate waves with many whitecaps.

Large branches sway, umbrellas used with difficulty, flags beat and pop, larger waves with regular whitecaps.

Sea heaps up, white foam streaks, whole trees sway, difficult to walk, large waves.

Twigs break off trees, moderately high sea with blowing foam.

Branches break off trees, tiles blown from roofs, high crested waves.

Some trees blown down, damage to buildings, high churning white seas and exceptionally high waves hiding ships from view.

Widespread damage to trees and buildings, mountainous waves, sea covered in white foam.

Severe and extensive damage.