Dictionary:

convection

  (kən-vĕk'shən)

(Click to enlarge)

convection

Air heated by a space heater rises and is replaced by cool air, creating a convection current that circulates hot air throughout a room. (Precision Graphics)

1. The act or process of conveying; transmission.
2. Physics.
   1. Heat transfer in a gas or liquid by the circulation of currents from one region to another.
   2. Fluid motion caused by an external force such as gravity.
3. Meteorology. The transfer of heat or other atmospheric properties by massive motion within the atmosphere, especially by such motion directed upward.

[Late Latin convectiō, convectiōn-, from convectus, past participle of convehere, to carry together : Latin com-, com- + Latin vehere, to carry.]

Concept

Convection is the name for a means of heat transfer, as distinguished from conduction and radiation. It is also a term that describes processes affecting the atmosphere, waters, and solid earth. In the atmosphere, hot air rises on convection currents, circulating and creating clouds and winds. Likewise, convection in the hydrosphere circulates water, keeping the temperature gradients of the oceans stable. The term convection generally refers to the movement of fluids, meaning liquids and gases, but in the earth sciences, convection also can be used to describe processes that occur in the solid earth. This geologic convection, as it is known, drives the plate movement that is one of the key aspects of plate tectonics.

How It Works

Introduction to Convection

Some concepts and phenomena cross disciplinary boundaries within the earth sciences, an example being the physical process of convection. It is of equal relevance to scientists working in the geologic, atmospheric, and hydrologic sciences, or the realms of study concerned with the geosphere, atmosphere, and hydrosphere, respectively. The only major component of the earth system not directly affected by convection is the biosphere, but given the high degree of interconnection between different subsystems, convection indirectly affects the biosphere in the air, waters, and solid earth.

Convection can be defined as vertical circulation that results from differences in density ultimately brought about by differences in temperature, and it involves the transfer of heat through the motion of hot fluid from one place to another. In the physical sciences, the term fluid refers to any substance that flows and therefore has no definite shape. This usually means liquids and gases, but in the earth sciences it can refer even to slow-flowing solids. Over the great expanses of time studied by earth scientists, the net flow of solids in certain circumstances (for example, ice in glaciers) can be substantial.

Convection and Heat

As indicated in the preceding paragraph, convection is related closely to heat and temperature and indirectly related to another phenomenon, thermal energy. What people normally call heat is actually thermal energy, or kinetic energy (the energy associated with movement) produced by molecules in motion relative to one another.

Heat, in its scientific meaning, is internal thermal energy that flows from one body of matter to another or from a system at a higher temperature to a system at a lower temperature. Temperature thus can be defined as a measure of the average molecular kinetic energy of a system. Temperature also governs the direction of internal energy flow between two systems. Two systems at the same temperature are said to be in a state of thermal equilibrium; when this occurs, there is no exchange of heat, and therefore heat exists only in transfer between two systems.

There is no such thing as cold, only the absence of heat. If heat exists only in transit between systems, it follows that the direction of heat flow must always be from a system at a higher temperature to a system at a lower temperature. (This fact is embodied in the second law of thermodynamics, which is discussed, along with other topics mentioned here, in Energy and Earth.) Heat transfer occurs through three means: conduction, convection, and radiation.

Conduction and Radiation

Conduction involves successive molecular collisions and the transfer of heat between two bodies in contact. It usually occurs in a solid. Convection requires the motion of fluid from one place to another, and, as we have noted, it can take place in a liquid, a gas, or a near solid that behaves like a slow-flowing fluid. Finally, radiation involves electromagnetic waves and requires no physical medium, such as water or air, for the transfer.

If you put one end of a metal rod in a fire and then touch the "cool" end a few minutes later, you will find that it is no longer cool. This is an example of heating by conduction, whereby kinetic energy is passed from molecule to molecule in the same way as a secret is passed from one person to another along a line of people standing shoulder to shoulder. Just as the original phrasing of the secret becomes garbled, some kinetic energy is inevitably lost in the series of transfers, which is why the end of the rod outside the fire is still much cooler than the one sitting in the flames.

As for radiation, it is distinguished from conduction and convection by virtue of the fact that it requires no medium for its transfer. This explains why space is cold yet the Sun's rays warm Earth: the rays are a form of electromagnetic energy, and they travel by means of radiation through space. Space, of course, is the virtual absence of a medium, but upon entering Earth's atmosphere, the heat from the electromagnetic rays is transferred to various media in the atmosphere, hydrosphere, geosphere, and biosphere. That heat then is transferred by means of convection and conduction.

Heat Transfer Through Convection

Like conduction and unlike radiation, convection requires a medium. However, in conduction the heat is transferred from one molecule to another, whereas in convection the heated fluid itself is actually moving. As it does, it removes or displaces cold air in its path. The flow of heated fluid in this situation is called a convection current.

Convection is of two types: natural and forced. Heated air rising is an example of natural convection. Hot air has a lower density than that of the cooler air in the atmosphere above it and therefore is buoyant; as it rises, however, it loses energy and cools. This cooled air, now denser than the air around it, sinks again, creating a repeating cycle that generates wind.

Forced convection occurs when a pump or other mechanism moves the heated fluid. Examples of forced-convection apparatuses include some types of ovens and even refrigerators or air conditioners. As noted earlier, it is possible to transfer heat only from a high-temperature reservoir to a low-temperature one, and thus these cooling machines work by removing hot air. The refrigerator pulls heat from its compartment and expels it to the surrounding room, while an air conditioner pulls heat from a room or building and releases it to the outside.

Forced convection does not necessarily involve man-made machines: the human heart is a pump, and blood carries excess heat generated by the body to the skin. The heat passes through the skin by means of conduction, and at the surface of the skin it is removed from the body in a number of ways, primarily by the cooling evaporation of perspiration.

Real-Life Applications

Convective Cells

One important mechanism of convection, whether in the air, water, or even the solid earth, is the convective cell, sometimes known as the convection cell. The latter may be defined as the circular pattern created by the rising of warmed fluid and the sinking of cooled fluid. Convective cells may be only a few millimeters across, or they may be larger than Earth itself.

These cells can be observed on a number of scales. Inside a bowl of soup, heated fluid rises, and cooled fluid drops. These processes are usually hard to see unless the dish in question happens to be one such as Japanese miso soup. In this case, pieces of soybean paste, or miso, can be observed as they rise when heated and then drop down into the interior to be heated again.

On a vastly greater scale, convective cells are present in the Sun. These vast cells appear on the Sun's surface as a grainy pattern formed by the variations in temperature between the parts of the cell. The bright spots are the top of rising convection currents, while the dark areas are cooled gas on its way to the solar interior, where it will be heated and rise again.

A cumulonimbus cloud, or "thunderhead," is a particularly dramatic example of a convection cell. These are some of the most striking cloud formations one ever sees, and for this reason the director Akira Kurosawa used scenes of rolling thunderheads to add an atmospheric quality (quite literally) to his 1985 epic Ran. In the course of just a few minutes, these vertical towers of cloud form as warmed, moist air rises, then cools and falls. The result is a cloud that seems to embody both power and restlessness, hence Kurosawa's use of cumulonimbus clouds in a scene that takes place on the eve of a battle.

A Sea Breeze

Convective cells, along with convection currents, help explain why there is usually a breeze at the beach. At the seaside, of course, there is a land surface and a water surface, both exposed to the Sun's light. Under such exposure, the temperature of land rises more quickly than that of water. The reason is that water has an extraordinarily high specific heat capacity—that is, the amount of heat that must be added to or removed from a unit of mass for a given substance to change its temperature by 33.8°F (1°C). Thus a lake, stream, or ocean is always a good place to cool down on a hot summer day.

The land, then, tends to heat up more quickly, as does the air above it. This heated air rises in a convection current, but as it rises and thus overcomes the pull of gravity, it expends energy and therefore begins to cool. The cooled air then sinks. And so it goes, with the heated air rising and the cooling air sinking, forming a convective cell that continually circulates air, creating a breeze.

Convective Cells Under Our Feet

Convective cells also can exist in the solid earth, where they cause the plates (movable segments) of the lithosphere—the upper layer of Earth's interior, including the crust and the brittle portion at the top of the mantle—to shift. They thus play a role in plate tectonics, one of the most important areas of study in the earth sciences. Plate tectonics explains a variety of phenomena, ranging from continental drift to earthquakes and volcanoes. (See Plate Tectonics for much more on this subject.)

Whereas the Sun's electromagnetic energy is the source of heat behind atmospheric convection, the energy that drives geologic convection is geothermal, rising up from Earth's core as a result of radioactive decay. (See Energy and Earth.) The convective cells form in the asthenosphere, a region of extremely high pressure at a depth of about 60-215 mi. (about 100-350 km), where rocks are deformed by enormous stresses.

In the asthenosphere, heated material rises in a convection current until it hits the bottom of the lithosphere (the upper layer of Earth's interior, comprising the crust and the top of the mantle), beyond which it cannot rise. Therefore it begins moving laterally or horizontally, and as it does so, it drags part of the lithosphere. At the same time, this heated material pushes away cooler, denser material in its path. The cooler material sinks lower into the mantle (the thick, dense layer of rock, approximately 1,429 mi. [2,300 km] thick, between Earth's crust and core) until it heats again and ultimately rises up, thus propagating the cycle.

Subsidence: Fair Weather and Foul

As with convective cells, subsidence can occur in the atmosphere or geosphere. The term subsidence can refer either to the process of subsiding, on the part of air or solid earth, or, in the case of solid earth, to the resulting formation. It thus is defined variously as the downward movement of air, the sinking of ground, or a depression in the earth. In the present context we will discuss atmospheric subsidence, which is more closely related to convection. (For more about geologic subsidence, see the entries Geomorphology and Mass Wasting.)

In the atmosphere, subsidence results from a disturbance in the normal upward flow of convection currents. These currents may act to set up a convective cell, as we have seen, resulting in the flow of breeze. The water vapor in the air may condense as it cools, changing state to a liquid and forming clouds. Convection can create an area of low pressure, accompanied by converging winds, near Earth's surface, a phenomenon known as a cyclone. On the other hand, if subsidence occurs, it results in the creation of a high-pressure area known as an anticyclone.

Air parcels continue to rise in convective currents until the density of their upper portion is equal to that of the surrounding atmosphere, at which point the column of air stabilizes. On the other hand, subsidence may occur if air at an altitude of several thousand feet becomes denser than the surrounding air without necessarily being cooler or moister. In fact, this air is unusually dry, and it may be warm or cold. Its density then makes it sink, and, as it does, it compresses the air around it. The result is high pressure at the surface and diverging winds just above the surface.

The form of atmospheric subsidence described here produces pleasant results, explaining why high-pressure systems usually are associated with fair weather. On the other hand, if the subsiding air settles onto a cooler lay of air, it creates what is known as a subsidence inversion, and the results are much less beneficial. In this situation a warm air layer becomes trapped between cooler layers above and below it, at a height of several hundred or even several thousand feet. This means that air pollution is trapped as well, creating a potential health hazard. Subsidence inversions occur most often in the far north during the winter and in the eastern United States during the late summer.

When a Non-Fluid Acts Like a Fluid

Up to this point we have spoken primarily of convection in the atmosphere and the geosphere, but it is of importance also in the oceans. The miso soup example given earlier illustrates the movement of fluid, and hence of particles, that can occur when a convective cell is set up in a liquid.

Likewise, in the ocean convection—driven both by heat from the surface and, to a greater extent, by geothermal energy at the bottom—keeps the waters in constant circulation. Oceanic convection results in the transfer of heat throughout the depths and keeps the ocean stably stratified. In other words, the strata, or layers, corresponding to various temperature levels are kept stable and do not wildly fluctuate.

Ocean waters fit the most common, everyday definition of fluid, but as noted at the beginning of this essay, a fluid can be anything that flows—including a gas or, in special circumstances, a solid. Solid rocks or solid ice, in the form of glaciers, can be made to flow if the materials are deformed sufficiently. This occurs, for instance, when the weight of a glacier deforms ice at the bottom, thus causing the glacier as a whole to move. Likewise, geothermal energy can heat rock and cause it to flow, setting into motion the convective process of plate tectonics, described earlier, which literally moves the earth.

Where to Learn More

Educator's Guide to Convection (Web site). <http://www.solarviews.com/eng/edu/convect.htm>.

Erickson, Jon. Plate Tectonics: Unraveling the Mysteries of the Earth. New York: Facts on File, 1992.

Hess, Harry. "History of Ocean Basins" (Web site). <http://www-geology.ucdavis.edu/~GEL102/hess/jesse.htm>.

Jones, Helen. Open-Ocean Deep Convection: A Field Guide (Web site). <http://puddle.mit.edu/~helen/oodc.html>.

Ocean Oasis Teacher's Guide Activity 4 (Web site). <http://www.oceanoasis.org/teachersguide/activity4.html>.

Santrey, Laurence, and Lloyd Birmingham. Heat. Mahwah, NJ: Troll Associates, 1985.

Scorer, R. S., and Arjen Verkaik. Spacious Skies. Newton Abbot, England: David and Charles, 1989.

Sigurdsson, Haraldur. Melting the Earth: The History of Ideas on Volcanic Eruptions. New York: Oxford University Press, 1999.

Skinner, Brian J., Stephen C. Porter, and Daniel B. Botkin. The Blue Planet: An Introduction to Earth System Science. 5th ed. New York: John Wiley and Sons, 1999.

Smith, David G. The Cambridge Encyclopedia of Earth Sciences. New York: Cambridge University Press, 1981.

The transfer of thermal energy by actual physical movement from one location to another of a substance in which thermal energy is stored. A familiar example is the free or forced movement of warm air throughout a room to provide heating. Technically, convection denotes the nonradiant heat exchange between a surface and a fluid flowing over it. Although heat flow by conduction also occurs in this process, the controlling feature is the energy transfer by flow of the fluid—hence the name convection. Convection is one of the three basic methods of heat transfer, the other two being conduction and radiation. See also Conduction (heat); Heat radiation; Heat transfer.

Natural convection is exemplified by the cooling of a vertical surface in a large quiescent body of air of temperature t_∞. The lower-density air next to a hot vertical surface moves upward because of the buoyant force of the higher-density cool air farther away from the surface. At any arbitrary vertical location x, the actual variation of velocity u with distance y from the surface will be similar to that in the illustration b, increasing from zero at the surface to a maximum, and then decreasing to zero as ambient surrounding conditions are reached. In contrast, the temperature t of the air decreases from the heated wall value t's to the surrounding air temperature. These temperature and velocity distributions are clearly interrelated, and the distances from the wall through which they exist are coincident because, when the temperature approaches that of the surrounding air, the density difference causing the upward flow approaches zero.

Temperature and velocity distributions in air near a heated vertical surface at arbitary vertical location. The distance δ is that distance at which the velocity and the temperature reach ambient surrounding conditions.

The region in which these velocity and temperature changes occur is called the boundary layer. Because velocity and temperature gradients both approach zero at the outer edge, there will be no heat flow out of the boundary layer by conduction or convection. See also Boundary-layer flow.

When air is blown across a heated surface, forced convection results. Although the natural convection forces are still present in this latter case, they are clearly negligible compared with the imposed forces. The process of energy transfer from the heated surface to the air is not, however, different from that described for natural convection. The major distinguishing feature is that the maximum fluid velocity is at the outer edge of the boundary layer. This difference in velocity profile and the higher velocities provide more fluid near the surface to carry along the heat conducted normal to the surface. Consequently, boundary layers are very thin.

Heat convection in turbulent flow is interpreted similarly to that in laminar flow. Rates of heat transfer are higher for comparable velocities, however, because the fluctuating velocity components of the fluid in a turbulent flow stream provide a macroscopic exchange mechanism which greatly increases the transport of energy normal to the main flow direction. Because of the complexity of this type of flow, most of the information regarding heat transfer has been obtained experimentally. See also Laminar flow; Turbulent flow.

Convection heat transfer which occurs during high-speed flight or high-velocity flow over a surface is known as aerodynamic heating. This heating effect results from the conversion of the kinetic energy of the fluid as it approaches a body to internal energy as it is slowed down next to the surface. In the case of a gas, its temperature increases, first, because of compression as it passes through a shock and approaches the stagnation region, and second, because of frictional dissipation of kinetic energy in the boundary layer along the surface.

The phenomena of condensation and boiling are important phase-change processes involving heat release or absorption. Because vapor and liquid movement are present, the energy transfer is basically by convection. Local and average heat-transfer coefficients are determined and used in the Newton cooling-law equation for calculating heat rates which include the effects of the latent heat of vaporization.

The process whereby heat is transferred from one part of a liquid or gas to another, by movement of the fluid itself. (Because, in meteorology, the most striking weather events are due to upward convection, it is possible to forget that all convection currents also have a downward component.) Convection carries excess heat from the earth's surface and distributes it through the troposphere.

In the atmosphere, warmer, lighter air moves upward and is replaced by colder, heavier air. This is free convection, or thermal convection, propelled by buoyancy. The upward movement of an air parcel over mountains, at fronts, or because of turbulence is known as forced convection, or mechanical convection. See also cumuliform convection, slope convection.

For more information on convection, visit Britannica.com.

Heat transmission, either natural or forced (by means of a fan), by currents of air resulting from differences in density due to temperature differences in the heated space.

The transfer of heat from one place to another by the motion of a gas or a liquid across the heated surface.

The motion of warm material that rises, cools off, and sinks again, producing a continuous circulation of material and transfer of heat. Some examples of processes involving convection are boiling water, in which heat is transferred from the stove to the air; the circulation of the atmosphere of the Earth, transferring heat from the equator to the North Pole and South Pole; and plate tectonics, in which heat is transferred from the interior of the Earth to its surface.

The act of conveying or transmission; specifically, transmission of heat in a liquid or gas by circulation of heated particles.

Movements of mantle material, laterally or in upward-downward directions, due to heat variations.

Convection in the most general terms refers to the movement of currents within fluids (i.e. liquids, gases and rheids).

Convection is one of the major modes of heat and mass transfer. In fluids, convective heat and mass transfer take place through both diffusion – the random Brownian motion of individual particles in the fluid – and by advection, in which matter or heat is transported by the larger-scale motion of currents in the fluid. In the context of heat and mass transfer, the term "convection" is used to refer to the sum of advective and diffusive transfer.^[1]

A common use of the term convection relates to the special case in which the advected (carried) substance is heat. In this case, the heat itself often causes the fluid motion, while also being transported by it. In this case, the problem of heat transport (and related transport of other substances in the fluid due to it) may be more complicated.

Mechanism of the special case of heat-driven heat convection

The mechanism of heat-driven convection is that uneven heating of fluids may cause uneven densities due to temperature driven expansion or contraction. In a gravity field (or other equivalent acceleration situation), such differences cause forces due to buoyancy of the less-dense parcels of fluid.

Purely heat-driven convection in gravity fields, especially that which itself carries heat, is sometimes referred to as "natural heat convection." A familiar example is the process that carries heated air upward from a fire or hot object.

Atmospheric heat-driven convection

Main article: Atmospheric convection

In the case of Earth's atmosphere, solar radiation heats the Earth's surface, and this heat is then transferred to the atmosphere by processes that are mostly convective. When a parcel of air is heated, it expands, becoming less dense and is pushed upward by buoyancy, carrying the heat energy upward with it. The air then cools, so it contracts, and sinks. The cycle then repeats with the cold air reheating and rising again. Since it cannot sink through the rising air beneath it, it moves laterally (sideways) and then begins to sink. These convection currents cause local breezes, winds, thermals, cyclones and thunderstorms, and at a larger scale, produce the global atmospheric circulation features.

A single region of air with a falling and rising current is called a convection cell.

Forced convection

Natural heat convection (also called free convection) is distinguished from various types of forced heat convection, which refer to heat advection by a fluid which is not due to the natural forces of buoyancy induced by heating. In forced heat convection, transfer of heat is due to movement in the fluid which results from many other forces, such as (for example) a fan or pump. A convection oven thus works by forced convection, as a fan which rapidly circulates hot air forces heat into food faster than would naturally happen due to simple heating without the fan. Aerodynamic heating is a form of forced convection.

Buoyancy induced convection not due to heat

Buoyancy forces which cause convection in gravity fields may result from sources of density variations in fluids other than those produced by heat, such as variable composition. For example, variable salinity in water and variable water content in air masses, are frequent causes of convection in the oceans and atmosphere, which do not involve heat (see thermohaline circulation). Similarly variable composition within the Earth's interior which has not yet achieved maximal stability and minimal energy (densest parts deepest) continues to cause a fraction of the convection of fluid rock and molten metal within the Earth's interior (see below).

Oceanic convection

Solar radiation also affects the oceans. Warm water from the Equator tends to circulate toward the poles, while cold polar water heads towards the Equator. Oceanic convection is also frequently driven by density differences due to varying salinity, known as thermohaline convection, and is of crucial importance in the global thermohaline circulation. In this case it is quite possible for relatively warm, saline water to sink, and colder, fresher water to rise, reversing the normal transport of heat.

Mantle convection

Main article: mantle convection

Convection within Earth's mantle is the driving force for plate tectonics. There are actually two convection currents occurring within the Earth. The outer core has an extremely rapid convective turnover of fluid metals (primarily iron and nickel) which are responsible for the Earth's magnetic field. The movement of metals forms electrical currents, which in turn generate magnetic fields.

As heat from the inner and outer core heat the lower portion of the mantle, a second set of convective currents form. This mantle convection is extremely slow, as the mantle is a thick semi-solid with the consistency of a very thick paste. This slow convection can take millions of years to complete one cycle.

Neutrino flux measurements from the Earth's core (see kamLAND) show the source of about two-thirds of the heat in the inner core is the radioactive decay of ⁴⁰K, uranium and thorium. This has allowed plate tectonics on Earth to continue far longer than it would have if it were simply driven by heat left over from Earth's formation; or with heat produced by rearrangement of denser portions to the centre of the earth.

Vibration convection in gravity fields

Vibration-induced convection occurs in powders and granulated materials in containers subject to vibration, in a gravity field. When the container accelerates upward, the bottom of the container pushes the entire contents upward. In contrast, when the container accelerates downward, the sides of the container push the adjacent material downward by friction, but the material more remote from the sides is less affected. The net result is a slow circulation of particles downward at the sides, and upward in the middle.

If the container contains particles of different sizes, the downward-moving region at the sides is often narrower than the larger particles. Thus, larger particles tend to become sorted to the top of such a mixture.

Scale and rate of convection

Convection may happen in fluids at all scales larger than a few atoms. Convection occurs on a large scale in atmospheres, oceans, and planetary mantles. Current movement during convection may be invisibly slow, or it may be obvious and rapid, as in a hurricane. On astronomical scales, convection of gas and dust is thought to occur in the accretion disks of black holes, at speeds which may closely approach that of light.

Pattern formation

Picture of the thermal field and its two-dimensional Fourier transform of a fluid under Rayleigh-Bénard convection [1]

Convection, especially Rayleigh-Bénard convection, where the convecting fluid is contained by two rigid horizontal plates, is a convenient example of a pattern forming system.

When heat is fed into the system from one direction (usually below), at small values it merely diffuses (conducts) from below upward, without causing fluid flow. As the heat flow is increased, above a critical value of the Rayleigh number, the system undergoes a bifurcation from the stable conducting state to the convecting state, where bulk motion of the fluid due to heat begins. If fluid parameters other than density do not depend significantly on temperature, the flow profile is symmetric, with the same volume of fluid rising as falling. This is known as Boussinesq convection.

As the temperature difference between the top and bottom of the fluid becomes higher, significant differences in fluid parameters other than density may develop in the fluid due to temperature. An example of such a parameter is viscosity, which may begin to significantly vary horizontally across layers of fluid. This breaks the symmetry of the system, and generally changes the pattern of up- and down-moving fluid from stripes to hexagons, as seen at right. Such hexagons are one example of a convection cell.

As the Rayleigh number is increased even further above the value where convection cells first appear, the system may undergo other bifurcations, and other more complex patters, such as spirals, may begin to appear. These may be familiar as examples from systems in which viscosity is relatively low and heat through-put high, such as the spiraling upward flow of gases in a fire.

See also

• Bénard cells
• Fluid dynamics
• Advection
  • Vortex dynamics
  • Thermomagnetic convection
• Grashof number
• Heat transfer
  • Heat conduction
  • Thermal radiation
  • Convective heat transfer
• Heat pipe
• Churchill-Bernstein Equation

References

1. ^ Frank P. Incropera; David P. De Witt (1990). Fundamentals of Heat and Mass Transfer, 3rd Ed., John Wiley & Sons. ISBN 0-471-51729-1. 

External links

• Correlations for Convective Heat Transfer
• Introduction to Mechanism of Free Convection

Meteorological data and variables
Atmospheric pressure · Baroclinity · Cloud · Convection · CAPE · CIN · Dew point · Heat index · Humidex · Humidity · Lifted index · Lightning · Pot T · Precipitation · Sea surface temperature · Surface solar radiation · Surface weather analysis · Temperature · Theta-e · Visibility · Vorticity · Wind chill · Water vapor · Wind

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - varmestrømning, konvektion

Nederlands (Dutch)
convectie

Français (French)
n. - (Phys, Élec) convection

Deutsch (German)
n. - (Phys.) Konvektion (Hitzetransfer)

Ελληνική (Greek)
n. - (φυσ.) μετάδοση/διάδοση (θερμότητας) με ρεύματα
attrib. - (φυσ.) μεταφοράς, εκ μεταφοράς

Italiano (Italian)
convezione

Português (Portuguese)
n. - convecção (f), transporte (m), propagação (f)
attrib. - aquele que propaga

Русский (Russian)
конвекция

Español (Spanish)
n. - convección

Svenska (Swedish)
n. - konvektion
attr. - konvektions-

中文（简体） (Chinese (Simplified))
传送, 对流

中文（繁體） (Chinese (Traditional))
n. - 傳送, 對流

한국어 (Korean)
n. - 대류, 전달

日本語 (Japanese)
n. - 伝達, 対流

العربيه (Arabic)
‏(الاسم) انتقال الحارة بواسطه الحمل (صفه)‏

עברית (Hebrew)
n. - ‮זרימת חום‬

If you are unable to view some languages clearly, click here.

To select your translation preferences click here.