Incandescence of Meteros

Abstract

THE electric currents which the author of the above letter regards as possibly constituting an efficient source of the luminosity of meteors must no doubt arise, and play a certain part in the heat and light development. But the measure in which they can be supposed to contribute to it must clearly be extremely small; or rather, it must be incomparably subordinate to the intense ignition of the air produced, not at all by friction¹, but by the air's adiabatic compression against the front surface of the meteorite; which is certainly quite competent, by itself alone, to develop what may be said to approach pretty nearly to fabulous degrees of temperature. If the kinetic energy of translation, in foot-pounds (v²/2g), of 1 lb. of the air propelled (at, say, 30 miles per second) with the meteor's speed (v feet/sec.) on its front face, be divided by 330, the number thus obtained (1,180,620° C., in the case supposed) will be the number of centigrade degrees through which it will be heated by the pure process of compression, supposing that the air can continue to subsist at all with its ordinary mechanical deportment and thermodynamical properties unaffected at that enormously high temperature. In the further forward, gradually advancing layers, and in the laterally escaping currents of the air, on which the high forward speed of the meteor is only partially impressed, and which move more slowly on their various courses, the compressions are correspondingly less, and the lower but still exceedingly high temperatures can be similarly calculated from any fair estimates of the air's collective or absolute velocity of translation in those different positions.