= Buoyant plume
A <buoyant plume> is a localized rising or sinking flow driven by a density difference from its surroundings. Heating fluid can lower its <mass density> and produce upward <buoyancy>; a denser injected fluid can produce a descending counterpart. The sign of the density anomaly and the direction of <gravity> specify the motion being described.
As a plume travels, <fluid entrainment> incorporates ambient fluid, increasing its <volume flux> and diluting the source anomaly. A warm narrow stream can therefore carry a growing amount of air while its mean excess <temperature> decreases. The <buoyancy flux> has a different balance from the volume transport, especially when the ambient fluid is stratified or heat is lost. Dye or temperature measurements across successive heights reveal widening and dilution; their interpretation requires the cross-sectional <velocity> as well as anomaly size to determine a transported flux.
Back to article page
