Facts about Convection
On astronomical scales, convection of gas and dust is thought to occur in the accretion disks of black holes, at speeds that may approach the speed of light.
Vibration-induced convection occurs in powders and granulated materials in containers subject to vibration, in a gravity field.
Oceanic convection is also frequently driven by density differences due to varying salinity, known as thermohaline convection, and is of crucial importance in the global thermohaline circulation.
The convection currents of the red liquid will be seen to rise and fall, then eventually settle, illustrating the process as heat gradients are dissipated.
A common use of the term convection leaves out the word "heat" but nevertheless refers to heat convection.
An example of gravitational convection is the diffusion of a source of dry salt downward into wet soil, assisted by the principle that, once the salt becomes wet, saline water is heavier than freshwater.
Convection currents occur on large scales in the Earth's atmosphere, oceans, and planetary mantle.
Common fluid heat-radiator systems, and also heating and cooling of parts of the body by blood circulation, are other familiar examples of forced convection.
A convection oven thus works by forced convection, as a fan that rapidly circulates hot air forces heat into food faster than would naturally happen due to simple heating without the fan.
Convection, especially Rayleigh-Bйnard convection, where the convecting fluid is contained by two rigid horizontal plates, is a convenient example of a pattern forming system.
Buoyancy-induced convection not due to heat is known as gravitational convection.
Current movement during convection may be invisibly slow, or it may be obvious and rapid, as in a hurricane.
In zero-g environments, there can be no buoyancy forces, and thus no natural (free) convection is possible.