Shear Assessment » Helicity Vorticity
Horizontal vorticity often results from vertical wind shear. A wind profile that maintains a single direction and increases its speed with height generates a shear vector parallel to the wind direction. This shear results in a horizontal vorticity whose axis (the vorticity vector) is perpendicular to the wind direction. We refer to this as crosswise vorticity. |
![]() |
On the other hand, a wind profile whose speed remains constant, but whose direction changes with height generates a shear vector perpendicular to the mean wind. The resulting vorticity vector is parallel to the mean wind. We refer to this as streamwise vorticity. In the real world, vorticity is rarely perfectly crosswise or streamwise. Thus, when we say streamwise vorticity we refer to the vector component of the vorticity that is oriented parallel to the mean flow. |
![]() |