What causes baroclinic instability?
Baroclinic instability is understood to be the dynamic cause for synoptic-scale, midlatitude storms. It is the result of a vertical shear in the basic-state zonal wind. The formal relationship is a consequence of the significance of the potential vorticity gradient for both instabilities. …
What is Barotropic instability?
The hydrodynamic instability arising from certain distributions of vorticity in a two-dimensional nondivergent flow. This is an inertial instability in that kinetic energy is the only form of energy transferred between current and perturbation.
What is a baroclinic instability?
Baroclinic instability refers to a process by which perturbations draw energy from the mean flow potential energy. The conversions of energy are proportional to perturbation heat fluxes in both horizontal and vertical directions. Baroclinic instability can be viewed as a shear instability.
What is baroclinic effect?
The baroclinic effect is due to the nonalignment of pressure and density gradients, and its result is to induce vorticity production. In the first section, the evolution of a flame front affected by a single baroclinic impulse is considered.
How is baroclinic instability investigated in the laboratory?
Baroclinic instability can be investigated in the laboratory using a rotating, fluid filled annulus. The annulus is heated at the outer wall and cooled at the inner wall, and the resulting fluid flows give rise to baroclinically unstable waves. The term “baroclinic” refers to the mechanism by which vorticity is generated.
How is the vorticity gradient related to baroclinic instability?
In baroclinic instability, the horizontal temperature gradient is the key source of a change in sign of the potential vorticity gradient. In fact, the conditions for instability can be satisfied even if the vorticity gradient is identically zero in the interior but a horizontal temperature gradient exists at the lower boundary.
How is wind shear related to baroclinic instability?
Thermal wind balance implies that wind shear accompanies baroclinic temperature gradients. Hence, addressing baroclinic phenomena requires a minimum of two levels for mean and perturbation geopotential in pressure coordinates. The β plane aproximation is applied.
How are eddies and baroclinic instability related?
The baroclinic instability theory indicates how depressions form in the atmosphere and how their initial structure is determined. Similarly, eddies can be generated in the ocean through instabilities of the mean flow.