wind

Wind is the motion of air relative to the surface of the Earth. It arises primarily from horizontal differences in air pressure created by the differential heating of the Earth's surface by the sun. Warm air rises where pressure is lower, and cooler air moves in to replace it, generating flow. The rotation of the Earth (Coriolis effect) deflects moving air, shaping large-scale wind patterns such as trade winds, the westerlies, and polar easterlies. At smaller scales, local winds develop from differences between land and sea, or between valleys and plateaus, including sea breezes, land breezes, mountain and valley breezes, and katabatic winds from elevated regions.

Wind is described by its speed and direction. Speed is commonly measured with an anemometer and reported in meters per second or knots; direction is the compass bearing from which the air is moving. The Beaufort scale provides qualitative descriptions of wind strength. Near-surface winds are influenced by surface roughness, terrain, and atmospheric stability.

Global wind patterns and jet streams influence weather and climate, while wind energy captures a portion of the kinetic energy of moving air using turbines. Wind also affects aviation, ship navigation, and erosion processes, and is a key factor in weather forecasting and climate models. Wind is highly variable across time and space, with gusts, shear, and turbulence posing challenges for operations and safety.