Potential vorticity

	Email		Print
	Bookmark		Link

Potential vorticity

Potential vorticity (PV) is a quantity which is proportional to the dot product of vorticity

Vorticity

Vorticity is a mathematical concept used in fluid dynamics. It can be related to the amount of "Circulation " or "rotation" in a fluid.The average vorticity in a small region of fluid flow is equal to the Circulation around the boundary of the small region, divided by the area A of the small region....
and stratification

Stratification

Stratification is the building up of layers, and can have several meanings*Social stratification, is the dividing of a society into levels based on wealth or Power ....
that, following a parcel

Air parcel

An air parcel is an imaginary volume of air used by meteorologists to conceptualize the thermodynamic fluid motions of the Earth's atmosphere for use in weather forecasting....
of air or water, can only be changed by diabatic

Diabatic

In quantum chemistry, the potential energy surfaces are obtained within the adiabatic process or Born-Oppenheimer approximation. This corresponds to a representation of the molecular wave function where the variables corresponding to the molecular geometry and the electronic degrees of freedom are separation of variable ....
or frictional processes. It is a useful concept for understanding the generation of vorticity in cyclogenesis (the birth and development of a cyclone), especially along the polar front

Polar front

In meteorology, the polar front is the boundary between the polar cell and the Ferrel cell in each hemisphere. At this boundary a sharp gradient in temperature occurs between these two air masses, each at very different temperatures....
, and in analyzing flow in the ocean.

It is also useful in tracing intrusions of stratospheric air deep into the troposphere

Troposphere

The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75% of the atmosphere's mass and almost all of its water vapor and particulate....
in the vicinity of jet streaks, a concentrated region within a jet stream

Jet stream

Jet streams are fast flowing, narrow thermal winds found at the tropopause, the transition between the troposphere and the stratosphere ,and are located at 10-15 kilometers above the surface of the Earth....
where the wind speeds are the strongest.

Discussion

Ask a question about 'Potential vorticity'

Start a new discussion about 'Potential vorticity'

Answer questions from other users

Full Discussion Forum

Encyclopedia

Potential vorticity (PV) is a quantity which is proportional to the dot product of vorticity

Vorticity

Stratification

Stratification is the building up of layers, and can have several meanings*Social stratification, is the dividing of a society into levels based on wealth or Power ....
that, following a parcel

Air parcel

Diabatic

Polar front

Troposphere

Jet stream

Flow tracer

A flow tracer is any fluid property used to track flow. The concentration of a chemical compound in the fluid can be used as a chemical tracer, and characteristics such as temperature are physical tracers....
in the ocean as well. It can also be used to explain how a range of mountains like the Andes

Andes

The Andes form the world's longest exposed mountain range. They lie as a continuous chain of highland along the western coast of South America. The range is over 7,000 km long, 200-700 km wide , and of an average height of about 4,000 m ....
can make the upper westerly winds swerve towards the equator

Equator

The equator is the intersection of the Earth's surface with the Plane perpendicular to the Earth's rotation and containing the Earth's center of mass....
and back.

Baroclinic instability requires the presence of a potential vorticity gradient along which waves amplify during cyclogenesis.

PV conservation

Mathematically, one form of potential vorticity is given by the equation: where is the fluid density

Density

The density of a material is defined as its mass per unit volume. The symbol of density is ....
, is the absolute vorticity

Vorticity

Gradient

In vector calculus, the gradient of a scalar field is a vector field which points in the direction of the greatest rate of increase of the scalar field, and whose magnitude is the greatest rate of change....
of the potential temperature

Potential temperature

The potential temperature of a Air parcel of fluid at pressure is the temperature that the parcel would acquire if Adiabatic process brought to a standard reference pressure , usually 1000 millibars....
. It can be shown through a combination of the first law of thermodynamics

First law of thermodynamics

In thermodynamics, the first law of thermodynamics is an expression of the more universal physical law of the conservation of energy. Succinctly, the first law of thermodynamics states:...
and momentum conservation that potential vorticity can only be changed by diabatic heating (such as latent heat released from condensation) or frictional processes. This conservation is the atmospheric equivalent to inertia

Inertia

File:192447main 017 law of inertia.oggInertia is the resistance of an object to a change in its state of motion. The principle of inertia is one of the fundamental principles of classical physics which are used to describe the Motion of matter and how it is affected by applied forces....
. A spinning ice skater with her arms spread out laterally can accelerate her rate of spin by contracting her arms. Similarly, when a vortex of air is broad, it is in turn, slow. When the air converges, to maintain potential vorticity, the air speed increases, resulting in a stretched rince vortex. Divergence causes the vortex to spread, slowing down the rate of spin.

Potential vorticity

PV conservation

See also