Why does convection occur?
Heat causes fluids to become less dense; so warmer fluids rise above cooler fluids, transferring energy.
Heat increases the kinetic energy of molecules; the molecules have greater energy when they collide, increasing energy transfer.
Heat is released during some types of reactions and absorbed during others, transferring energy to the system or surroundings.
Heat flows through the air as electromagnetic radiation, transferring energy without matter.
Convection occurs as a result of heat transfer from a hotter region to a cooler region in a fluid, such as air or water. It happens due to the relationship between heat and fluid density.
When a fluid is heated, the molecules within it gain energy and start moving more quickly. This increase in kinetic energy causes the molecules to collide with one another more frequently, leading to an overall increase in energy transfer. As a result, the warmer fluid becomes less dense than the cooler fluid.
Since denser fluids tend to sink, the cooler and denser fluid displaces the warmer and less dense fluid, causing it to rise. This upward movement of the warm fluid and downward movement of the cool fluid creates a circulation pattern known as convection currents.
Convection is a major contributor to heat transfer in everyday situations. For example, it plays a vital role in the distribution of heat in the Earth's atmosphere and oceans, as well as in cooking food on a stove.