Vertical Shear- The rate of change of wind speed or direction, with a given change in height.
Polar JetMarked by a concentration of isotherms and strong vertical shear, this jet is the boundary between the polar air and the subtropical air.
BRKBreakBRN(Bulk Richardson Number) A non-dimensional number relating vertical stability and vertical shear (generally, stability divided by shear).
Mixing DepthVertical distance between the ground and the altitude to which pollutants are mixed by turbulence caused by convective currents or vertical shear in the horizontal wind.
Looking north from about 15 miles, we see a storm embedded in strong vertical shear. Upper level winds near cloud summit were blowing from west to east (left to right) at 130 MPH.
Vertical shear (which doesn't have to be throughout the troposphere, but can also be over a very shallow layer) destroys the convection around the centre of the tropical cyclone (the 'eye').
Energy Helicity Index (or EHI) - An index that incorporates vertical shear and instability, designed for the purpose of forecasting supercell thunderstorms.
Marked by a concentration of isotherms and strong vertical shear, this jet is the boundary between the polar air and the subtropical air.
Thus, higher values indicate unstable conditions and/or strong vertical shear. Since both parameters are important for severe weather development, higher values generally indicate a greater potential for severe weather.
The vertical shear can be expressed in terms of height ¶[∂]V/¶[∂]z or of pressure ¶[∂]V/¶[∂]p as the vertical coordinate. If the wind is geostrophic, the vertical shear is given by the thermal wind equation.
Helicity is proportional to the strength of the flow, the amount of vertical shear, and the amount of turning in the flow (i.e. vorticity).
The Bulk Richardson Number is a dimensionless number in meteorology relating vertical stability and vertical shear (generally, stability divided by shear).
Bulk Richardson Number (or BRN) - a non-dimensional (i.e., no units) number relating vertical stability to vertical shear (generally, stability divided by shear).
SUBTROPICAL JET Marked by a concentration of isotherms and vertical shear, this jet is the boundary between the subtropical air and the tropical air.
Cloud street Clouds aligned in rows due to strong vertical shear in horizontal wind speed or direction.
Cold air advection Flow of air from relatively cool localities to relatively warm localities.
where g is the acceleration of gravity, β a representative vertical stability (commonly ∂θ/∂z, where θ is potential temperature), and ∂u/∂z is a characteristic vertical shear of the wind.
Strong winds aloft providing vertical shear over an extratropical storm strengthen it, as well as having a greater difference between the warm and cold air masses.
For example, it does not take in account the specific effects of directional and speed shear components. High values indicate unstable and/or weakly-sheared environments; low values indicate weak instability and/or strong vertical shear.
 See also: Shear, Storm, Surface, Wind, Air
  
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