It will be a hole lot of screen dumps.
The easiest way to try to measure 20m jumps without a device is by boosting next to a friend who has his kite straight up.
If you can see the upper graphics on the kite your high (as a kite
The condition where really crazy. The wind went from 23kn to about 40knots or more in gusts, guessing. The biggest jumps were when I got hit by freak gust in mid air. In those kind of jumps you go almost straight up. It's not your every day jump.
Imagine you're self on a 8m high ar kite when 40kn gusts hits you mid air. The lift was quite violent and scary at some of the jumps.
If I hadn't my Woo on the board I wouldn't jumped in those gusts. My biggest regret was not to bring my camera
I didn't expect those kind of conditions. The other guys were on 9 and 10m. For the record I've been kite for about 10 years and consider myself a very experienced kiter.
Would nice to get someone to stand under you and point a laser distance meter to see the hight and compare it with the Woo.