An investigation of whistling atmospherics
An investigation of whistling atmospherics
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呼啸大气的调查
DOI：
10.1098/rsta.1953.0011
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发表时间：
1953
期刊：
影响因子：
--
通讯作者：
L. R. O. Storey
中科院分区：
文献类型：
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作者：
L. R. O. Storey
本文分两部分，描述了有时在低于15 kc/s的频率下观察到的“哨声大气”或“哨声”的性质和起源的调查。第一部分是对哨声性质的实验研究，记录和分析了大量的哨声，确定了哨声频率随时间的变化规律。一些哨声被听到跟随着脉冲大气，并且这些哨声被发现是由在大约2000公里的距离内发生的雷击以正常的方式产生的。其他的哨声没有大气层的伴随，它们在几个方面与前一种不同。还研究了这两种哨声性质的日变化和年变化。本文的第二部分详细阐述了巴克豪森（1930）和埃克斯利（1935）关于哨声大气起源的理论。该理论提出，它们是由于波起源于正常的脉冲大气层，并穿过外电离层，遵循地球磁场的力线，并在很高的高度穿过赤道。在他们的旅程中，他们变得分散，以便作为“口哨”到达。它们可能会从地球表面沿同一路径沿着反射回来，一次或多次，产生色散增加的哨声。负责引导波沿着地磁场的线的效应提供了足够的聚焦作用，以防止能量被不适当地扩散。哨声的分散程度的测量已经被解释为产生关于在非常高的高度大气中的电子密度的信息。所需的密度似乎比合理预期的要大得多。如果自由电子是由地球大气电离产生的，那么这些区域的温度至少为7200° K。另一种解释是，假设电子是从外部落进来的，如果是这样的话，就可以解释哨声的出现与磁活动之间的关系。
The paper, which is in two parts, describes an investigation of the nature and origin of the ‘whistling atmospherics’ or ‘whistlers’ which are sometimes observed at frequencies below 15 kc/s. The first part describes an experimental study of their properties, in the course of which a considerable number of whistlers were recorded and analyzed, and the law of the variation of their frequency with time determined. Some whistlers are heard to follow impulsive atmospherics, and these are found to be produced in the normal way by lightning strokes taking place within a distance of about 2000 km. Other whistlers are unaccompanied by atmospherics; they differ from the former type in several further respects. The diurnal and annual variations of the properties of both types of whistler have also been studied. In the second part of the paper a theory of the origin of the whistling atmospherics, originally due to Barkhausen (1930) and Eckersley (1935), is developed in detail. The theory proposes that they are due to waves which originate in normal impulsive atmospherics and travel through the outer ionosphere, following the lines of force of the earth’s magnetic field and crossing over the equator at a great height. During their journey they become dispersed so as to arrive as ‘whistlers’. They may be reflected from the earth's surface back along the same path, one or more times, to produce whistlers with increased dispersions. The effects responsible for the guiding of the waves along the lines of the geomagnetic field provide sufficient focusing action to prevent the energy from being spread unduly. Measurements of the degree of dispersion of the whistlers have been interpreted to yield information about the density of electrons in the atmosphere at very great heights. The density required seems considerably larger than could reasonably have been expected. If the free electrons are produced by ionization of the terrestrial atmosphere its temperature m these regions must be at least 7200° K. The results might alternatively be explained on the assumption that the electrons are falling in from outside, and if this were so it might account for the relationship between the occurrence of whistlers and magnetic activity.