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Atmospheric convection is the vertical transport of heat and moisture in the atmosphere.It occurs when warmer, less dense air rises, while cooler, denser air sinks. This process is driven by parcel-environment instability, meaning that a "parcel" of air is warmer and less dense than the surrounding environment at the same altitude.
Convection is also seen in the rising plume of hot air from fire, plate tectonics, oceanic currents (thermohaline circulation) and sea-wind formation (where upward convection is also modified by Coriolis forces). In engineering applications, convection is commonly visualized in the formation of microstructures during the cooling of molten ...
This force occurs between two colliding plates where one is subducting beneath the other. As one plate subducts, it sets up convection currents in the upper mantle that exert a net trenchward pull, and acts to suck both the plates together. [2] Slab suction is weaker than slab pull, which is the strongest of the driving forces.
The figure is a schematic diagram depicting a subduction zone. The subduction slab on the right enters the mantle with a varying temperature gradient while importing water in a downward motion. A model of the subducting Farallon slab under North America. In geology, the slab is a significant constituent of subduction zones. [1]
The polar cell is a simple system with strong convection drivers. Though cool and dry relative to equatorial air, the air masses at the 60th parallel are still sufficiently warm and moist to undergo convection and drive a thermal loop. At the 60th parallel, the air rises to the tropopause (about 8 km at this latitude) and moves poleward.
Forced convection: when a fluid is forced to flow over the surface by an internal source such as fans, by stirring, and pumps, creating an artificially induced convection current. [ 3 ] In many real-life applications (e.g. heat losses at solar central receivers or cooling of photovoltaic panels), natural and forced convection occur at the same ...
Convection causes it to rise, causing a valley breeze. At night, the process is reversed. During the night the slopes get cooled and the dense air descends into the valley as the mountain wind. [4] These breezes occur mostly during calm and clear weather. Mountain and valley breezes are other examples of local winds caused by an area's geography.
Convection is caused by yeast releasing CO2. In fluid dynamics, a convection cell is the phenomenon that occurs when density differences exist within a body of liquid or gas. These density differences result in rising and/or falling convection currents, which are the key characteristics of a convection cell. When a volume of fluid is heated, it ...