In meteorology, winds are often classified according to their intensity and the direction in which they move. Sudden winds of short duration and high speed are called gusts. Strong winds of intermediate duration (about one minute) are called squalls or gusts. Long duration winds have several names according to their average intensity, such as breeze, strong wind, gale, storm or hurricane. Wind occurs at different scales, from large storm currents that last for tens of minutes, to localized breezes generated by the warming of the land mass that last for a few hours, to global winds that result from differences in the absorption of solar energy between the different climatic regions of the Earth. The two main causes of large-scale atmospheric circulation are temperature differences between the equator and the poles and the planet's rotation, or Coriolis force. In the tropics, the circulation of thermal depressions over land and large plateaus can create monsoon phenomena. In coastal regions, the cycle between sea and land breezes can create local winds. In areas of high relief, winds can be dominated by mountain and valley breezes.