Understanding the Wind Window is critical for managing the power of the kite and your direction of travel. This is basic theory that your kitesurfing lessons will cover.
The Wind Window is defined relative to the rider. The Wind Window is the three dimensional region of sky downwind of the rider in which the kite can be flown. When facing downwind, the wind window is roughly all the area the you can see.
Wind Window viewed from the side
Kitesurfers use a clock-type notation to describe the kite location and placement in the wind window.
When your kite is directly overhead at 12 O'Clock, this is also referred to as the Zenith. Avoid this position when on the beach
You should launch and land your kite at either 9 O'Clock or 3 O'Clock.
Wind Window clock notation viewed by rider looking downwind
Wind Window zones
There are three main zones within the Wind Window:
The Edge of the Wind Window is where the kite generates the least power. This is the zone used for launching and landing the kite, or for parking it in a neutral position while in the water.
The Intermediate Zone is where the kite generates medium power. You will fly the kite through or in this zone when the wind strength is good and you are cruising.
The Power Zone is where the kite generates maximum power. You will fly the kite through or in this zone when you want maximum power - for example when you are doing a water start or the wind speed is fairly low.
Three main zones in Wind Window (approximate only)
A kite flown out of the Wind Window will stall and is likely to fall out of the sky.
Do not fly your kite at 12 O'Clock when on the beach. A strong gust of wind with the kite in this position could result in you being lofted into the air and carried some distance, with a high risk of impact with something solid. Injuries and deaths have resulted from this.
If your kite is about to stall, you can reach up and pull on the front lines to keep in flying.
Direction of travel
Kitesurfers only use half the wind window depending on their direction of travel.
Right quadrant of Wind Window used when travelling to starboard (right)
Left quadrant of Wind Window used when travelling to port (left)
To generate maximum power for doing a water start in lighter winds, fly your kite first a short distance in the opposite direction, then bring it back in your direction of when diving it through the power zone. For example, if you are doing a water start for a right (starboard) tack, first fly your kite to 11 O'Clock (left quadrant) then bring it to 12 O'Clock, then dive it into the right quadrant of the wind window.
Apparent wind effect
The faster you go the more "apparent wind" you create, which has the effect of pushing the wind window behind you. The effect of this is:
Slower board speed - easier to upwind.
Higher board speed - harder to go upwind.