All sports
Wind gradient
The change in wind speed and direction with height above the surface — friction slows wind near the ground.
Also known as: wind shear, boundary layer wind
Surface friction means wind is slower at ground level than 100 metres up. The vertical profile is the wind gradient (sometimes called wind shear when the change is sharp). Over flat water it’s mild — perhaps 10% slower at sea level than at 10 m. Over forest or city it can halve.
Why riders care:
- A kite at 25 m altitude feels noticeably more wind than a windsurf sail at 5 m
- A foil rider sitting above the board catches a different airflow than someone planing on the deck
- Thermal breakdowns at sunset often hit the surface first — the gradient inverts before the wind dies completely
Most weather models report 10 m wind; your actual rig is somewhere on a curve up from that.
Related reading: GFS vs ICON, Types of Wind.
Related terms
- Gust A short, sharp increase in wind speed lasting seconds, well above the average.
- Fetch The unobstructed distance of open water over which the wind blows in one direction — controls how big and clean waves get.
- Gradient wind The large-scale wind driven by pressure differences between weather systems — the synoptic background flow that everything else rides on top of.