Convection is the heating process by which heat travels through air, water, and other gases. It is the heat transferred due to the bulk movements of molecules with the fluids such as gases and liquids includes molten rocks. Convection takes place through advection, diffusion or both. It occurs due to the fluid that is heated becomes less dense, and as a result, it rises. Convection is the major factor in weather. The sun heats the earth’s surface and when the cooler air comes in contact with it, the air warms and rises, creating an upward current in the atmosphere. The current can result in the wind, clouds, or other weather. Convection currents within the earth move layers of magma and convection in the ocean creates currents. Convection ovens use fans to circulate heat so that whatever you are cooking cooks faster and more properly.
A convection current is a process which involves the movement of energy from one place to another. Convection current transfers heat by mass motion of a fluid such as water air or molten rocks. The heat transfers function of conversation currents drives the earth’s ocean currents, atmospheric and weather. It is different from conduction which is a transfer of heat between substances in direct contact with each other. Convection currents are an important form of heat transfer. Convection occurs when heat cannot efficiently be transferred through radiation of thermal conduction. In astronomy, convection currents occur in the mantle of the earth and on other planets, and convection zone of the sun.
Examples of convection:
- Boiling water: The heat is carried to the burner then into the container, heating the water at the bottom then this hot water rises and cooler water moves down to replace it causing a circular motion.
- Radiator: Puts the warm air at the top and becomes cooler at the bottom.
- A cup of steaming hot tea: The steam that is coming from hot tea is being transferred into the air.
- Melting ice: from the air, heat move to the ice due to which the ice melts from solid to liquid.
- Hot air balloons: The heater present inside the balloon heats the air and so the air moves upward. This causes the balloon to rise because the hot air gets trapped inside.
Difference between convection and conduction:
Conduction and convection are similar in that both mechanisms require the presence of a material medium. On the other hand, they are different in that convection requires the presence of fluid motion. Conduction is the transfer of heat in the material due to molecular motion, such that energy transfers through matter from particle to particle. Convection is the transfer of heat between a solid surface and the adjacent fluid that is a motion by the actual movement of the warmed matter.
Facts about convection:
- The heat source and liquid are needed to form convection current therefore, heat transfer can be conducted.
- Convection occurs in the atmosphere. The air is considered as the fluid, while the sun is considered as the heat source.
- Magma is considered as the fluid, while the core of the earth is called as the heat source.
- Convection is important since it can affect the weather. The large masses of gases, liquids, and solids can be removed by the circulating fluid of the convection current. The movement of tectonic plates on the earth’s crust occurs because of the convection currents. Other phenomena affected by convection currents include the production of ocean currents and wind in the atmosphere.
- The most effective way to transfer the heat via gases and liquids is by using the convection current even though both are considered as the poor conductors of heat.