Forcing for Upward Motion
1. Synoptic Scale: QGOmega Equation
Vertical Motion at Given Level (say, in the
midtroposphere)

Prop
To

Vorticity Advection
*
*(Really, differential vorticity advection centered at the level)

and/or

Temperature Advection at that Level

and/or

Sensible Temperature Change at that Level

and/or

Friction*
*(Really, differential friction centered at the level)



Term A


Term B


Term C


Term D

Description


Vertical motion
Related to Divergence/Convergence
aloft associated with instantaneous geometry of the pattern (e.g., troughs/ ridges)


Vertical motion
Related to Divergence/Convergence
aloft associated with thermal (temperature advection) development of the pattern (e.g., pressure rises/falls) 

Vertical motion
Related to Divergence/Convergence
aloft associated with thermal (sensible heating/cooling) development of the pattern (e.g., pressure rises/falls) 


Visualization


Vertical
Motion Associated With
"Dynamic*" Surface Pressure Systems
(Terms A and B)
*Generally connected to the stronger flow patterns associated with jet streams/low level jets etc. of baroclinic systems. However, Term C can modify the effects of Terms and B.


Vertical Motion Associated With "Thermal*" Surface Pressure Systems
(Term C)
*Seen uniquely only when Terms A and B are small or negligible. Generally connected to the usually weaker flow patterns (with no temperature advection) of barotropic systems.



The magnitude of the vertical velocity at a given level is directly proportional to (Term A + Term B + Term C + Term D). Note that meteorologists tend to look at each of these terms in isolation from one another. In the real atmosphere, Term C accounts alone for vertical velocity fields (and pressure patterns) only if the other terms are small/negligible, for example, during the summer over the middle latitude continents.
2. Nonsynoptic Scale (Not what forecasters refer to as "Dynamics")
1. Fronts (Solenoidallydirect): Upward in warm air,
downward in cold air
2.
Thermodynamics: Spontaneous
Upward Motion for Rising Air Parcels Above LFC