What causes the force of the wind?

Answer 1

Basically, wind is just air movement. There's a lot of very complicated physics involved in exactly how the air moves (which is why weather forecasting is so difficult) but this is basically how it works: Warm air rises and cold air sinks (because it's denser), so if one area of the earth's surface gets warmer (e.g. due to sunlight), the warm air rises which leaves less air there, so nearby air flows in to fill the gap - much like if you lift a bucket of water out of a pool, the nearby water rushes in to fill in the gap. That air flowing in is what we feel as wind.

Answer 2

High pressure will always tend to go to low pressure. When you hear a meteorologist talk of the barometer, it simply is one way of saying how high or low the atmospheric pressure is in a certain area.
A high pressure zone will travel toward a low pressure zone. As it does, wind is generated. The higher the high pressure and the lower the low pressure the higher the wind velocity.

Answer 3

Wind will move because of the difference in pressure. Any liquid or gases will follow the same theory. The air is also a type of gas.