The Invisible Wall
Wind doesn't pass through solid objects. It flows over and around them, creating a zone of disturbed air behind every obstacle. This is the wind shadow—and it's one of the most dangerous zones for launching.
Inside a wind shadow, the air is chaotic, gusty, and unpredictable.
⚠️ Launch Risk
Launching in a wind shadow causes wing flips, sudden lulls, and violent gusts. Your wing experiences different wind speeds at different heights simultaneously, making it impossible to control.
The Shadow Rules
Wind shadow extent depends on obstacle height and shape:
Turbulence Distance Rules
Smooth Obstacles (buildings, walls)
Shadow extends 7-10x height downwind
Rough Obstacles (forests, cliffs)
Shadow extends 15-20x height downwind
Vertical Cliffs
Shadow extends 20-30x height downwind + creates violent updrafts
Shadow Zone Calculations
Real-world examples of turbulence distances:
Turbulence Distance Examples
5m tree line
75-100m shadow
10m building
70-100m shadow
20m forest
300-400m shadow
50m cliff
1000-1500m shadow
100m mountain
2-3km shadow
What Happens Inside the Shadow
Wind shadow turbulence manifests in several dangerous ways:
- Wind shear: Top of wing gets wind, bottom doesn't—wing flips violently
- Gustiness: Sudden 0-15 knot swings every few seconds
- Rotors: Horizontal vortices that can slam you into the water
- Direction shifts: Wind comes from random angles, impossible to position wing
- Dead zones: Complete wind loss for 5-10 seconds at a time
The Danger Zone Experience
Launching in a wind shadow feels like this:
- Wing fills, then collapses, then fills again
- Wing tip hits the water while you're still standing
- Sudden gust flips the wing over your head
- You can't waterstart because wind keeps changing
- Frustration builds—you're exhausted before you even start riding
How to Identify Good Launch Sites
Use these criteria to evaluate launch spots:
Clean Air Checklist
Trace wind backwards: Where does it come from before reaching you?
Look for clear water fetch: At least 1km of open water upwind
Avoid urban downwind zones: Towns create massive turbulence
Check for cliffs/forests upwind: Calculate shadow using 20x rule
Cross-shore is safer than onshore: Reduces shadow impact
If obstacles exist, position perpendicular: Side wind reduces turbulence
When You're Stuck in a Shadow
If you must launch from a shadowed spot:
- Walk downwind: Move beyond the turbulence zone before launching
- Use larger wing: Helps maintain power through lulls
- Launch aggressively: Get on foil fast before wind shifts
- Expect frustration: It's not your skill—it's physics
Summary
Launch where the wind has a clear path from open water. Avoid spots where wind blows over towns, forests, or cliffs before reaching you. Calculate shadow distances using the 7x-20x height rule and position yourself outside the turbulence zone.