What Is Convection?

Convective activity in the Earth's atmosphere

The areas of heating and cooling are usually fixed. The convective currents that develop when a saucepan of water over a flame rises to the surface are related to the temperature of the water. The water sinks back to the bottom of the saucepan after being cooled enough.

The process of convective activity helps to redistribute energy away from hotter areas to cooler areas of the Earth, aiding temperature circulation and reducing temperature differences. Without the use of a heat ring at the bottom of the kettle, boiling water in a kettle would be much slower as the water at the top would stay cool. The rising and sinking of cooler areas of liquid or gas can form a complete cycle.

Convective heat transfer through a fluid

Mass transfer or heat transfer is the two main types of convection. Liquids and gases can transfer heat quickly by the way of convection. Advection, diffusion or both are the ways in which the air is moved.

Significant dispersal of matter and bulk current flows can't take place in most solid objects. Thermal conduction is the process of Diffusion of heat in rigid solids. Energy flow is only possible through the process of conduction, even at the surface.

There is always a thin stagnant fluid film layer on the heat transfer surface. In the next layers there is movement in themolecular level or the macroscopic level. The rate of energy transfer is higher when there is mass movement.

The stagnant fluid film layer will be thinner if the rate of mass movement is higher. The heat transfer through a fluid is done by two processes: convection in the presence of mass movement and by the absence of it. The case of quiescent fluid can be seen as the limiting case of thermal conduction.

The rate of heat loss of a body is directly proportional to the temperature difference between the body and its surroundings if the nature of the surface remains the same. The convective heat transfer coefficients are dependent on the physical properties of the fluid. The convective heat transfer coefficients are not a part of the fluid.

Solar Radiation, Wind and Hydrologic Activity

The solar radiation per unit area is highest at the heat equator and decreases as the latitude increases. The polar vortex and the Hadley cell are the primary cells that experience stronger convection due to the release of heat energy by condensation of water vapor at higher altitudes. The wind and the cycle of the hydrologic are more local than global atmospheric movement.

A foehn wind is a down-slope wind which occurs on the side of a mountain range. The air on the leeward slopes is warmer than the air on the wind because of the different adiabatic lapse rates. The visible tops of the cells in the photoosphere are caused by the activity of the plasma in the photoosphere.

The rising part of the granules is located in the center. The outer edge of the granules is darker. A typical granule has a diameter of 1,000 kilometers and lasts 8 to 20 minutes before dissipating.

The layer of larger "supergranules" up to 30,000 kilometers in diameter are covered by the photoosphere. Convection can happen in fluids of all sizes. There are a variety of circumstances in which the forces required for the formation of the convection are needed.

Body forces acting within the fluid are what causes the convection. In a zero-gravity environment, there can be no buoyancy forces, and thus no convection possible, so flames in many circumstances without gravity smothering their own waste gases. The flame can be ventilated by using thermal expansion and chemical reactions resulting in contraction gases.

Heat Transfer by Bodies

The mechanisms of heat transfer are Convection and Radiation. They allow thermal energy to be moved. The main difference between the two is that radiation involves a mass flow of material while the other is a mechanism of heat transfer.

Radiation is a transfer of heat using energy. Radiation can transfer heat through a vacuum. When the movement of material is done using an external mechanism, it is called forced convection.

Fan heaters are an example of forced convection. The human body has a pump in the heart that helps to circulate heat around it. The quantity is called emissivity.

It takes a value between 0 and 1. It is higher for objects with darker surfaces. The surfaces absorb and emit less radiation.

A blackbody is a surface that is both a perfect absorber and an emitter of radiation. The primary wavelength of the radiation by bodies is in the red range. The graph shows the energy density of a wavelength at different temperatures.

The Smart Slide-In Range

A conventional oven has heating elements that heat the air inside. The heating element at the bottom of the oven is used for cooking and baking, while the heating element at the top is used for broiling. The dish that cooks the fastest is the closest to the heating element.

Which oven will help you make after-school snacks, bake cookies for the bake sale or have dinner at the table between soccer practice and ballet class? You can ask Whirlpool to help you decide. The Smart Slide-In Range is designed to help you cut down on steps to get food to the table.