The deviations are caused by the Coriolis force and conservation of potential vorticity which leads to changes of relative vorticity.
2.
Thus, as a fluid parcel moves equatorward ( ?y approaches zero ), the relative vorticity must increase and become more cyclonic in nature.
3.
Also the above approximation " U " > > " u "'ensures that the perturbation flow does not advect relative vorticity.
4.
Conversely, if the same fluid parcel moves poleward, ( ?y becomes larger ), the relative vorticity must decrease and become more anticyclonic in nature.
5.
Where f is the Coriolis parameter, \ sigma is related to the geostrophic velocity vector, \ zeta _ g is the geostrophic relative vorticity, \ phi is the geopotential, \ nabla ^ 2 _ H is the horizontal Laplacian operator and \ nabla _ H is the horizontal del operator.
6.
Considering a parcel of air that has no relative vorticity before perturbation ( uniform " U " has no vorticity ) but with planetary vorticity " f " as a function of the latitude, perturbation will lead to a slight change of latitude, so the perturbed relative vorticity must change in order to conserve potential vorticity.
7.
Considering a parcel of air that has no relative vorticity before perturbation ( uniform " U " has no vorticity ) but with planetary vorticity " f " as a function of the latitude, perturbation will lead to a slight change of latitude, so the perturbed relative vorticity must change in order to conserve potential vorticity.
8.
Because of conservation of potential vorticity caused by the northward-moving winds on the subtropical ridge's western periphery and the increased relative vorticity of northward moving water, transport is balanced by a narrow, accelerating poleward current, which flows along the western boundary of the ocean basin, outweighing the effects of friction with the western boundary current known as the Labrador current.
मोबाइल