Winds generally blow from an area of high pressure to an area of low pressure. This is due to the difference in air pressure caused by uneven heating of the Earth's surface by the sun. When air is heated, it becomes less dense and rises, creating an area of low pressure. Conversely, when air cools, it becomes more dense and sinks, creating an area of high pressure. As air moves from high pressure to low pressure, it creates wind. The greater the difference in pressure between the two areas, the stronger the wind will be. This movement of air from high to low pressure is known as the pressure gradient force and is the main driving force of wind.