By Ross Nuechterlein Convection Convection is the movement of molecules within fluids and is one of the major modes of heat and mass transfer in liquids and gas Buoyancy Buoyancy is an upward acting force exerted by a fluid that opposes an objects weight ID: 179866
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Slide1
Convection & Buoyant Force
By Ross
NuechterleinSlide2
Convection
Convection
is the movement of molecules within fluids and is one of the major modes of heat and mass transfer in liquids and gas.Slide3
Buoyancy
Buoyancy
is an upward acting force exerted by a fluid , that opposes an object's weight.
Buoyancy = weight of displaced fluid.Slide4
Convection Cells
A change in
Temperature, Salinity
or
Density
causes a fluid parcel to have
vertical
tendencies until a great enough force is achieved. Until then: Transport takes place horizontally
till the downward force becomes greater than the rising force below. Slide5
Types of Convection
Natural Convection
Gravitational Convection
Forced Convection
Granular Convection
Thermo magnetic convection.Slide6
Natural Convection or Free Convection
Occurs due to temperature differences affecting density resulting in buoyancy (more or less dense)
This leads to bulk fluid movement.
More rapid movement between two fluids of large density differences.
Larger acceleration occurs through greater mediumsSlide7
Gravitational Convection
Induced by buoyancy variations resulting from material properties other than temperature.
Variable salinity in water is a frequent cause of ocean convection.
Dependant on the effects of gravity and does not occur in micro gravity environmentsSlide8
Wind Driven Convection CellsSlide9
Circulation
Solar radiation warms the oceans near the Equator, driving warm water toward the poles.
Cold polar water replaces displaced warm water at the equator creating circulation. Slide10
Density differences also drive ocean convection due to varying salinity. This is known as
Thermohaline
convection.
In some cases warm saline water may sink being replaced by cooler fresher water which rises. This reverses the transport of heat. Slide11Slide12
Deep Ocean circulation is important because it determines the vertical stratification of the ocean and because it also modulates climate.
This circulation is caused by the convection processes discussed. Slide13
References
Stewart, R. H., 2002.
Introduction to Physical Oceanography
.Open ocean convection: observations, theories, models.
http://www.math.nyu.edu/caos_teaching/ocean_dynamics/reading/marshall_schott99.pdf