Answer:
Winding mills are made on hills because of air flow and currents.
Step-by-step explanation:
Winding mills capture wind to turn blades and produce energy. In order to do so, it needs winds! Strong winds, in order to turn the blades. You will notice that if you ever scale a mountain or go higher, it starts to become windier/the wind blows harder.
If the wind mills are placed higher, it can capture these windier conditions, thus moving the wind blades to produce energy. The higher the hill, the stronger the wind current, the more energy it produces.