| 单词 | sporadic e |
| 释义 | > as lemmassporadic E b. sporadic E-layer, sporadic-region: a discontinuous region of ionization that occurs from time to time in the E-layer of the ionosphere and results in the anomalous reflection back to earth of VHF radio waves. Also elliptical as sporadic E, sporadic-E, used attributively and absol. ΘΚΠ the world > the earth > weather and the atmosphere > [noun] > specific regions of > specific regions of ionosphere Heaviside layer1911 F-region1928 D-region1930 E-region1930 sporadic E-layer1937 ledge1949 protonosphere1960 topside1962 the world > matter > physics > electromagnetic radiation > radio wave > [noun] > layer reflecting long or waves Heaviside layer1911 E-layer1930 sporadic E1937 sporadic E-layer1937 1937 Terrestrial Magnetism XLII. 76 No relation between the sporadic E-region ionizations and magnetic disturbances of widespread character is apparent so far. 1949 Nature 2 Apr. 528/2 The usual measure of sporadic E-layer ionization is the so-called ‘critical frequency’, that is, the highest reflected frequency for this layer. 1955 Sci. Amer. Sept. 129/1 One of the outstanding mysteries of the ionosphere is a type of irregularity called ‘sporadic E’. 1967 Economist 22 July 280/1 UHF is virtually immune to sporadic-E problems which so beset VHF. 1974 E. Harnischmacher in F. Verniani Struct. & Dynamics of Upper Atmosphere 272 The Sporadic E layer, Es, is the most irregular and the thinnest layer of the ionosphere. < as lemmas |
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