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Supercells. MICRO-. PHYSICS. Physical processes controlling cell types:. Buoyancy processes: basic updraft/downdraft, (ordinary cells) Gust front processes : triggering of new cells, upscale growth, (multicells)
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MICRO- PHYSICS
Physical processes controlling cell types: • Buoyancy processes: basic updraft/downdraft, (ordinary cells) • Gust front processes: triggering of new cells, upscale growth, (multicells) • Dynamic processes: rotating updraft, dynamic vertical pressure gradient forcing, (supercells)
Physical processes controlling cell types: • Buoyancy processes: basic updraft/downdraft, (ordinary cells) • Gust front processes: triggering of new cells, upscale growth, (multicells) • Dynamic processes: rotating updraft, dynamic vertical pressure gradient forcing, (supercells)
Momentum Eq. Dynamic Pressure Eq. --
Linearise pressure eq. about U(z), V(z) (environmental vertical wind shear) So, since
Vorticity Equation: Vertical Vorticity: tilting stretching
Vortex Tube Circulation:
Theorems for inviscid fluids with conservative external forces (e.g., no baroclinicity, buoyancy) (Helmholtz, 1858) ….Vortex lines (tubes) are material lines that are frozen into the fluid. ….The circulation (strength) of a vortex tube is invariant …The circulation on any curve around a vortex tube is constant along the tube.
Tilting: Linearized about a mean vertical wind shear:
Vertical Momentum Eq. (rewritten) (dynamic) + (buoyancy)
(H = horizontal shearing deformation) So, for a wind profile in pure rotation: So, again, since
Supercell Hodographs: Supercell processes are Galilean invariant!!!
Linearise pressure eq. about U(z), V(z) (environmental vertical wind shear) So, since