A critical survey of ionospheric temperatures

摘要: The relative order of importance the various methods available for evaluation temperature from an ionospheric parameter is (a) and collisional frequency, (b) auroral scale heights, (c) electron concentration, (d) influx function, (e) recombination coefficient. Method (e), still in its infancy, does not yet permit accurate evaluations ionosphere. Some indication a diurnal variation may be obtained method (d). probable temperature-altitude relationship atmospheric regions 100-400 km., as determined by several techniques, tabulated below: Upper Atmospheric Temperatures (°K.) Altitude (km.) Determination Collisional frequencies Auroral heights Electron concentration 100 300 219 - 150 825 531 200 1350 1580 250 2175 2073 2400 2455 330 1530-2680 350 3225 2704 400 3450 500 2200-3910 These values are considered to represent mean annual temperatures at middle latitudes. gas essentially identical. If free electrons have excess energy (as result during ionization process) this quickly distributed among other particles. Thermal equilibrium therefore Maxwellian velocity distribution particles exists gaseous constituents range km. kinetic equivalent temperature. Fluctuation phenomena deviations probably do occur terrestrial atmosphere until much higher altitudes. A totally ionized below agree with experimental evidence inasmuch deduced on such basis will support observed number density. Tentatively it has been shown that no large variations found altitude Preliminary estimates rate heating based upon dissipation absorbed process appear confirm preceding statement. However, attributable non-detectable absorption processes, electrical currents ionosphere or bombardment numbers high unknown. existence than those given above Table would difficult explain atmosphere. Indeed, qualitatively concluded maximum near somewhat Above maximum, general decrease occurs meet boundary interstellar space. arises processes together sufficient density