The direct cause of formation of the wind, is the horizontal pressure gradient force. By the winds of atmospheric circulation, terrain, water and other factors, various forms, such as the monsoon, local sea-land breeze, wind, foehn, valley. Simply put, wind is air in molecular motion. To understand the causes of the wind, you have to figure out two key concepts: air and air pressure. Air consists of: molecular nitrogen ( accounting for total air volume 78% ), molecular oxygen (approximately 21%), water vapor and other trace elements. All the molecules of air moving at a rapid rate, rapid collision between each other, and the horizon of any object collision.