convection question for science final

convection in weather

"Convection" has several, related meanings in weather....but it always involves rising air. It usually refers to "moist convection", where the excess water vapor in rising air parcels condenses to form a cloud. The heat released through this condensation can help to sustain the convection by warming the air further and making it rise still higher, which causes more water vapor to condense, so the process feeds on itself. But convection can also be dry, as occurs on a sunny day over the desert, or in more humid regions early in the day before the convection has become strong enough to form clouds. The sun warms the ground, and convective air currents help to remove the excess heat from the surface. Dry convection also occurs during the day even when clouds are not forming...you just can't see it.

driving force for convection to occur

Convection may happen in fluids at all scales larger than a few atoms. There are a variety of circumstances in which the forces required for natural and forced convection arise, leading to different types of convection. In broad terms, convection arises because of body forces acting within the fluid, such as gravity, or surface forces acting at a boundary of the fluid. The causes of convection are generally described as one of either "natural" or "forced", although other mechanisms also exist. However the distinction between natural and forced convection is particularly important for convective heat transfer.

forced convection

In forced convection, also called heat advection, fluid movement results from external surface forces such as a fan or pump. Forced convection is typically used to increase the rate of heat exchange. Many types of mixing also utilize forced convection to distribute one substance within another. Forced convection also occurs as a by-product to other processes, such as the action of a propeller in a fluid or aerodynamic heating.

convection in geology

Mantle convection is the slow creeping motion of Earth's solid silicate mantle caused by convection currents carrying heat from the interior of the Earth to the surface. Mantle convection is the slow creeping motion of Earth's rocky mantle caused by convection currents carrying heat from the interior of the earth to the surface. It is the driving force that causes tectonic plates to move around the Earth's surface.

convection

Process by which, in a fluid being heated, the warmer part of the mass will rise and the cooler portions will sink. Don't mistake for conduction which happens on contact

convection in astronomy

The convection zone of a star is the range of radii in which energy is transported primarily by convection. It is the outermost layer of the sun. The convection zone surrounds the radiative zone. In the convection zone, hot material from near the Sun's center rises. This material cools at the surface, and then plunges back downward. The material then receives more heat from the radiative zone.