Russell, and is remarkable in this respect, that the quantity of air admitted to the fuel, the loss by convection and radiation, and the composition of the smoke were determined.
These results show how extremely accurate the observations must have been, and that the loss mainly arises from convection and radiation from the boiler.
Convection is responsible for winds and ocean currents, for land and sea breezes, and other daily phenomena.
Even in these processes of convection and radiation, a similar law prevails to that which is discovered in examining into the rate of calorific absorption.
Before, however, we proceed to the examination of the phenomena of terrestrial heat, a few of the great results of the laws of radiation and convection claim our attention.
It is obvious that this should be the case, but the result cannot generally be applied toconvection currents.
Moreover, although the effects of cooling by convection currents are practically eliminated by exhausting to 3 or 4 mm.
The rate of loss of heat by radiation, and also by convection and conduction to the surrounding air, increases much more rapidly than in simple proportion to the temperature difference, and the rate of increase of each follows a different law.
The low conducting power of such materials is principally due to the presence of air in the interstices, which is prevented from forming convection currents by the presence of the fibrous material.
This has been verified experimentally by Kundt and Warburg, Stefan and Winkelmann, by taking special precautions to eliminate the effects of convectioncurrents and radiation.
The rate of loss by convection and conduction varies greatly with the form of the surface, and, unless the enclosure is very large compared with the cooling body, the effect depends also on the size and form of the enclosure.
Thus radiation differs from conduction and convection in taking place most perfectly in the absence of matter, whereas conduction and convection require material communication between the bodies concerned.
Molecular convection or diffusion, which cannot be distinguished experimentally from conduction, as it follows the same law, is also the main cause of conduction of heat in liquids.
In space void of matter, we should have pure radiation, but it is difficult to obtain so perfect a vacuum that the effects of the residual gas in transferring heat by conduction or convection are inappreciable.
This coefficient represents the rate of loss of heat from a body per unit area of surface per degree excess of temperature, and includes the effects of radiation, convection and conduction.
In reality the effect is due chiefly to the greater velocity of motion of the ultimate molecules of hydrogen, and is most marked if molar (as opposed to molecular) convection is eliminated.
In general, the less the gradient, that is, the less the contrast between the temperature at the surface and higher up, the less convection takes place.
The presence of carbon dioxide lessens convection because it increases the absorption of heat in the zone above the level in which water vapor is abundant, thus warming these higher layers.
The climatic effects of such extensive lava flows would be essentially as follows: In the first place so long as the lavas were hot they would set up a local system of convection with inflowing winds.
The amount of water vapor in the air diminishes as convection increases, since upward convection is a chief method by which condensation and precipitation are produced, and water vapor removed from the atmosphere.
This is because the trades are produced by the convection due to excessive heat along the heat equator.
The most important of these was the rapid upward convectionin the centers of cyclonic storms whereby abundant heat was carried to high levels where most of it was radiated away into space.
Local convection would also be strengthened in harmony with the expansion of the lands, for the more rapid heating of land than of water favors active convection.
In summer, when the gradient is steepest, convection reaches its maximum.
Local convectionis influenced by carbon dioxide because this gas lessens the temperature gradient.
Beneath the convective ceiling the process of convection is characteristic, and this zone is therefore described as the convective zone (Fig.
Convection currents must, therefore, adjust themselves by the air expanding as it rises.
An electron in motion is analogous to a convection current; therefore every magnetic field, in particular that due to the luminous perturbation itself, must exert a mechanical action upon this electron.
There are also the cases in which electric discharges describe a closed contour, being displaced by conduction in one part of the circuit and by convection in the other part.
It seemed that if the current were closed, it could only be by the current of convection itself.
But Rowland has proved that currents of convection produce the same magnetic effects as currents of conduction; they should produce also the same effects of induction.
For example, if we connect by a wire the two poles of a Holtz machine, the charged rotating disc transfers the electricity by convection from one pole to the other, and it returns to the first pole by conduction through the wire.
For that it sufficed to assume that a 'convection current,' that is to say a charged conductor in motion, could act on the galvanometer.
The air is not warmed by the passage of the sun's heat through it, but by convection from the earth, in the same way that it is warmed by the surfaces of stoves.
A very good illustration of the convection of heat," said Mr. Wilton, "is seen in the common method of heating water.
Even at a distance, the dangerous potential of the cloud is reduced by these convection currents and the stroke ordinarily averted.
To sum the contents of this essay in the most general terms, we find that in the conception of denudation as producing the convection and accumulation of radiothermal energy the surface features of the globe receive a new significance.
Sedimentation from this point of view is a convection of energy.
Table 1 gives the sizes of fire-clay flue linings ordinarily provided for boilers, furnaces, stoves, or convection heaters burning soft coal.
The quantity and temperature of the heated air discharged from the grilles in figures 20 and 21 were measured to determine the merits of the convection features.
In mild climates a properly built fireplace will heat a single room, and when equipped with a convection heater will also heat a second room on the same floor or an upper floor.
If he gazed through to the bottom he detected a convectionin the sand below.
It took many a night's meditation for the evolution of any fixed idea from the bewilderingconvection of thought.
From the bottom of the Nile a turbid convection was taking place, as if the river silt had been stirred up, but the fuming current was assuming a dull red tinge.
Make a cross-section sketch of your living room and indicate the convection currents by which the room is heated.
The trade winds are convection currents moving toward the hot equatorial belt from both the north and the south.
Ultimately he found that this was due to convection currents in the case containing the torsion rod, currents produced by temperature inequalities.
Convection currents constitute the chief disturbance and the chief source of error in all attempts to measure small forces in air at ordinary pressure.
Besides, theconvection of heat is greater in the former bulb.
When the currents are steady there is practically no bombardment, and convection may therefore with such currents also considerably modify the degree of incandescence and produce results similar to those just before shown.
Could the tubes be so highly exhausted that convection would be nil, then the relative amounts of heat given off by convection and radiation could be determined without the difficulties attending thermal quantitative measurements.
He showed also some interesting experiments in which the effect of convection is illustrated.
The convection on the contrary should be the smaller, the higher the frequency.
Were the variation sufficiently rapid, such a destructive break would not occur, no matter how great the force, for all the energy would be spent in radiation, convection and mechanical and chemical action.
Professor Ayrton and Mr. Kilgour some time ago published quantitative results concerning the thermal emissivity by radiation and convection in which the effect with thin wires was clearly shown.
Disregarding now the modifying effect of convection there are then two distinct causes which determine the incandescence of a wire or filament with varying currents, that is, conduction current and bombardment.
In this construction, of course, the small bulb becomes very hot and when it reaches an elevated temperature the convection and radiation on the outside increase.
This was explained in a plausible way by assuming that the convection was not widely different in the dense and rarefied places, and that the bombardment was greater on the dense places of the striated discharge.
In these experiments the gas acts in two opposite ways in determining the degree of the incandescence of the filaments, that is, by convection and bombardment.
Whether or not convection is important at the microscopic level remains an experimentally unsolved question.
This phenomenon would cause equilibration to occur much more slowly than that occurring with free convection and diffusion.
Free convection flow is a macroscopic phenomenon which increases not only with g, but varies also approximately with the five-fourths power of the bulk concentration involved.
Free convection flow is a major transport process, and under its influence the mixing of substances is much more effective than when diffusion operates alone.
The Grashoff number limits freeconvection to the macroscopic domain.
Though I have no decisive fact to quote at present, I cannot refrain from venturing an opinion, that the effect is analogous both to combination and convection (1623.
Whether convection or carrying discharge will produce the same phenomenon has not been determined, and the few experiments I have as yet had time to make do not enable me to answer in the affirmative.
Aided by convection currents in the air and in the ocean it continually equalises temperatures, but does so at an immense cost of useful energy.
The heat which arrives at the surface of the earth is radiated to the atmosphere or carried off by convection currents; there is no doubt that it is lost from the earth.
It is only possible to give here a very short indication of the thermodynamic treatment, and of the nature of Thomson's remarkable discovery of the electric convection of heat.
As the power available from convection currents is very slight, every care must be taken that the figure will work smoothly.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "convection" in a variety of sentences. We hope that you will now be able to make sentences using this word.
