Rate of change of wind velocity with distance perpendicular to the wind direction. A very narrow zone of abrupt velocity change is known as a shear line. Wind shear is observed near the ground and in jet streams, where it may be associated with clear-air turbulence. Vertical wind shear is closely associated with the vertical flux of momentum, heat, and water vapour.

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For similarly pronounced words, see sheer, Shere, or sher.

Shear as a noun may refer to:

• Bias (textile), in clothing design, fabric may be cut on the shear
• Cosmic shear, an effect of distortion of image of distant galaxies due to deflection of light by matter, as predicted by general relativity (see also gravitational lens)
• Shear (geology), a form of fault in rocks
• Guillotine (metalwork), also called a shear, a machine used to cut sheet metal
• Simple shear, a special case of deformation of a fluid
• Shear (fluid), in fluid dynamics, refers to the shear stresses and responses thereto in fluids
• Shear mapping, a particular type of mapping in linear algebra, also called transvection
• Shear rate, a gradient of velocity in a flowing material
• Shear stress in physics, refers to a stress state that will cause shearing (see verb) when it exceeds a material's shear strength
• Shear strength (soil), the shear strength of soil under loading
• Shear line (locksmithing), where the inner cylinder ends and the outer cylinder begins in a cylinder lock
• Shear line (meteorology), an area of wind shear
• Wind shear, a difference in wind speed or direction between two wind currents in the atmosphere
• Shear wall, in structural engineering
• Shear forming in metal working (manufacturing), a metal spinning

Shear as a verb or shearing may refer to:

• Shearing (physics), the deformation of a material substance in which parallel internal surfaces slide past one another
• Shearing (metalworking), a metalworking process
• Shearing interferometer, in optics, a simple and very common means to check the collimation of beams by observing interference
• Sheep shearing, the process of removing the wool from a sheep
• Shearing in computer graphics, more commonly called page tearing

SHEAR as an acronym may refer to:

• Society for Historians of the Early American Republic, dealing with United States History 1775-1861