The force responsible for causing air movement is known as pressure gradient force. To display wind speeds, the pressure gradient is plotted onto a weather map using isobars that are mapped between areas of low and high pressure.
Bars that are spaced close together are an indication of strong winds and steep pressure gradient force. Bars spaced far apart are an indication of light winds and gradual pressure gradient. In the atmosphere, there are a number of forces that have an impact on the direction and speed of winds. However, the most important is Earth’s gravitational force. Without gravity, there would be no wind, air pressure or atmosphere.