Examples of Convection

In last weeks physics friday we discussed convection. Before I will give some examples where convection occurs in nature I will shortly repeat the basics (quote from physics.info): "Convection is the transfer of internal energy into or out of an object by the physical movement of a surrounding fluid that transfers the internal energy along with its mass. Although the heat is initially transferred between the object and the fluid by conduction, the bulk transfer of energy comes from the motion of the fluid. Convection can arise spontaneously (or naturally or freely) through the creation of convection cells or can be forced by propelling the fluid across the object or by the object through the fluid. "

For the examples we focus on spontaneous convection. Spontaneous convection is mainly driven by buoyancy but also surface tension plays a role to a lesser extent.

Some of the physical processes most influencing people's live are driven by convection:

Atmospheric circulation on a local level through anabatic (updraft) and katabatic (downdraft) winds.

But also on a global scale atmospheric circulation is driven by convection - tropical and polar cells are common termini in weather reports.
Ocean currents are driven by a combination of temperature and salinity gradients (thermohaline circulation) in the deep ocean, by winds near the surface, and by topography everywhere water touches land. Examples include the gulf stream, the historical first reported ocean current, and the deep ocean return current both effecting the local (the gulf stream for example keeps eurpoe warmer than north america at the same lattitude) or the global climate.
Also geologic effects like plate tectonics are driven by mantle convection and the outer core convection (along with charge separation) generates earth's magnetic field.


From the above examples you see that convection is really an important physical effect really influencing people's everyday live. The role of convection in finance will be discussed in our next physic's friday blog.