Convection currents form because a heated fluid expands, becoming less dense. The less-dense heated fluid rises away from the heat source. As it rises, it pulls cooler fluid down to replace it.

mantle

Mantle convection is the very slow creeping motion of Earth’s solid silicate mantle caused by convection currents carrying heat from the interior to the planet’s surface. This hot added material cools down by conduction and convection of heat.

Convection currents occur within: the atmosphere – wind. the hydrosphere – ocean currents.

Convection currents describe the rising, spread, and sinking of gas, liquid, or molten material caused by the application of heat. Tremendous heat and pressure within the earth cause the hot magma to flow in convection currents. These currents cause the movement of the tectonic plates that make up the earth’s crust.

Convection occurs when heat is transferred through a gas or liquid by the hotter material moving into a cooler area. Discover what convection really is and review several examples of this phenomenon.

Natural convection can occur when there are hot and cold regions of either air or water, because both water and air become less dense as they are heated. In nature, convection cells formed from air raising above sunlight-warmed land or water are a major feature of all weather systems.

In natural convection, any fluid motion is caused by natural means such as the buoyancy effect, i.e. the rise of warmer fluid and fall the cooler fluid. Whereas in forced convection, the fluid is forced to flow over a surface or in a tube by external means such as a pump or fan.

Natural convection, known also as free convection is a mechanism, or type of mass and heat transport, in which the fluid motion is generated only by density differences in the fluid occurring due to temperature gradients, not by any external source (like a pump, fan, suction device, etc.).

A natural convection oven works with a fan that has a heating element around, providing the heat. Natural convection is a type of heat transport where the fluid motion is not generated by an external source. In this process the fluid that surrounds a heat, becomes less dense and rises.

Very simply put, a convection oven has a fan and exhaust system that a regular oven does not. The fan and exhaust help blow hot oven air over and around the food, then vent it back out. As a result, this hot air surrounds the food so that it cooks evenly and more quickly.

Free convection refers to fluid motion induced by buoyancy forces. Buoyancy forces may arise in a fluid for which there are density gradients and a body force that is proportional to density. In heat transfer, density gradients are due to temperature gradients and the body force is gravitational.

The convection caused by winds is natural convection for the earth, but it is forced convection for bodies subjected to the winds since for the body it makes no difference whether the air motion is caused by a fan or by the winds.

Convection is the transfer of heat energy through the movement of fluid particles. Hence, convection cannot take place in solids, since the solid particles are not fluid. Thus, convection only takes place in liquids and gases.

Convection, process by which heat is transferred by movement of a heated fluid such as air or water. Natural convection results from the tendency of most fluids to expand when heated—i.e., to become less dense and to rise as a result of the increased buoyancy.

gases

Convection happens because warm air is less dense than the cold air around it, so it is lighter and rises or goes up in the atmosphere. There is a constant balancing act going on all the time in our atmosphere as moist, warm air goes upward and cooler, denser air moves down.

Convection cannot take place in most solids because neither bulk current flows nor significant diffusion of matter can take place. Convection, additionally may take place in soft solids or mixtures where solid particles can move past each other.

While conduction is the transfer of heat energy by direct contact, convection is the movement of heat by actual motion of matter; radiation is the transfer of energy with the help of electromagnetic waves. The matter is present around us, in three states, solid, liquid and gas.

Conduction is the transfer of thermal energy through direct contact. Convection is the transfer of thermal energy through the movement of a liquid or gas. Radiation is the transfer of thermal energy through thermal emission.