Here you can find a lot of helpful knowledge about Kitesurfing.
The wind window is the area where the kite can fly. On its edge, the kite generates its minimal power, because it only receives the true wind. It is also where we use the kite clock as reference for teaching. Positions 9 and 3 o'clock are also called launching and landing positions. 12 o’clock can be called the Zenith too. On the center of the wind window, the kite will be able to accelerate and create an “induced wind” which associated to the “true wind” will be called “apparent wind”. This is where the kite can generate its maximum power.
The Drop Zone
The drop zone is located under the wind window. The drop zone must be kept clear of any obstacle for the rider’s safety and others’. Do you know how to calculate it? The drop zone is anywhere underneath the wind window where the kite can drop, plus the size of the leash in extension and the size of the kite span in the case the rider releases the chicken loop quick release. This means that for a 12 m kite on 25 m lines, the diameter of the drop zone will be around 60 m!!! This is one of the reason why IKO uses short lines to teach beginners.
The Safety Zone
The safety zone corresponds to 3 lines length. This is the area beyond the drop zone that a pilot keeps clear of any obstacles because it takes time and distance to stop a kite. When the wind is stronger, the size of the safety zone should be increased. A cautious kiteboarder should also keep a safety zone upwind of him and not let another kiter get too close.