What Is Convection Essays - Meteorology, Continuum Mechanics

What Is Convection ? Convection is the heat transfer in a gas or liquid by the circulation of currents from one region to another or convection can also be defined as a flu i d motion caused by an external force of gravity. Convection is heat transfer by circulating currents of air as in 'THERMALS' in the atmosphere. Heated air has a lower density than cool air and therefore rises. Cooler air moves in below the rising warm air and circulatory currents are set up. Thermals are used by Hang-gliders and Para-gliders to gain lift. Convection is also used in space heating as in the home. Radiation is due to rays of direct heat as from the sun or an open fire . It is the phys ical movement of warm air (or other fluid) into an area of cooler air (or other fluid). Normally the movement is vertical as the horizontal movement is called advection. Significant evidence can be found in many places in the natural world. The first one that comes to mind is the development of cumulonimbus clouds. Warm, moist air flow upwards because it is more buoyant than the surrounding air. As it moves upwards it cools as it expands and eventually forms clouds. Another example would be the convective cells found in hot springs. The hot water is less dense and rises, sometimes quite vigorously, producing a lot of turbulence at the surface.