Maintain even pressure to maintain turn shape and speed control. A board or ski turns best when there is enough pressure to flex it like a bow. Usually the act of standing still is enough pressure to bend the ski or board. (camber)
I emphasize control because a goal of good riders is to maintain even steady pressure on your board of choice from the beginning of the turn to the end.
Ways to pressure.
Up-unweight.
Down-unweight
Terrain unweight
Retraction
Extension
Up-unweighting
Extend the legs rapidly and abruptly stop that movement. Your mass stays elevated momentarily. (your feet stay light) during this time your ski or board is light or even slightly airborne.
PRO: An easy way to start a turn, especially when managing difficult snow conditions.
CON: Takes a lot of strength to make continuous turns this way. Each time you come back in contact with the snow, there is instability as the edge tries to reorient itself.
Down-unweighting
Dropping down or dipping in your legs so rapidly that your mass floats in the air momentarily. (Your feet get light) The Vomit Comet comes to mind.
PRO: Very quick movement is useful in emergencies to aid in quicker turn initiation.
CON: Once you make this move you run out of room to move and stay in good balance.
Terrain-unweighting
Simply put. Every time your skis or board ride over a rise that acts like a teeter-totter to turn yourself, you used the terrain change to lighten the ski. Launching a jump or having the hill drop away suddenly is other examples.
Retraction
Flexing legs when the ground rises at you. Similar to absorption. The goal is to keep even pressure at the feet. Useful in moguls and powder.
Extension
Extending your legs when the ground drops away to increase pressure. Very handy in moguls and powder.
