Trinka

Turbulence is any form of chaotic change in the wind direction, and doesn't come from obstacles only. It can also come from the air rising up because of the hot ground. You can really notice that when flying over drying cut grass, roads or asphalt runways, or really hot days. Also turbulence from obstacles can reach really high and far, especially if there are high mountains around.

Exactly. During my AFF I was jumping with weights. When I've finished it and started jumping solo without them, I had a similar problem. The only thing I've did is just tried to arch more. Anyway, I've stopped falling like a "ship on waves" after 3 or 4 more jumps. Don't mind it that much, it will go away as you get more experience. After awhile you'll see that you can fall stable even without arching.