Wind is the movement of large bodies of air. Air is made up of gas molecules and those molecules are already whizzing around – that’s what makes air a gas instead of a solid. But the motion of individual molecules is chaotic. They are constantly bouncing off one another and changing direction. When you add all the trillions of tiny collisions together, you get an overall pressure that increases as the temperature rises, because the molecules are moving faster. Air at the equator gets heated by the Sun more than air at the poles so it exerts a greater pressure and pushes the colder air out of the way. Because the Earth is also rotating, the atmosphere gets pulled into huge vortices. These rotating pressure systems move across the planet and we feel the result as wind. The exact pattern of the wind is further complicated by differences between the temperature of the land and sea, obstructions from mountains and buildings and even the energy released when water vapour condenses as rain. This is why predicting the weather is so hard!
Answered by Luis Villazon.