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 barotropic and baroclinic conditions?
BAROTROPIC- Region of uniform temperature distribution; A lack of fronts. The tropical latitudes are barotropic. There are no fronts in the tropics. BAROCLINIC- Distinct air mass regions exist.
What is baroclinic torque?
The baroclinic torque →B is the mechanism by which density variations influence vorticity. This torque is zero in the case of a barotropic fluid (section 6.6. 2), where ρ=ρ(p), because →∇ρ and →∇p are then parallel.
What is the cause of baroclinic instability?
In baroclinic instability, the horizontal temperature gradient, which is proportional to vertical shear of the wind through the thermal wind relation, is the key source of a change in sign of the potential vorticity gradient.
What is barotropic instability?
Barotropic instability proceeds with the extraction of kinetic energy from the horizontally sheared flow to feed the growing meander. The greater the shear in the jet, the more likely is this type of instability.
What is the relationship between baroclinic instability and thermal wind instability?
The formal relationship is a consequence of the significance of the potential vorticity gradient for both instabilities. In baroclinic instability, the horizontal temperature gradient, which is proportional to vertical shear of the wind through the thermal wind relation, is the key source of a change in sign of the potential vorticity gradient.
How do baroclinic instabilities grow?
Baroclinic instabilities grow by converting available potential energy to kinetic energy; the horizontal temperature gradient associated with vertical shear of the mean flow is the source of this available potential energy. Examples of the traditional method of instability analysis are to be found in Holton (1992).