Chapter 3 - Collisionless Hydrodynamic Generators in a Planetary Atmosphere

Abstract

In this chapter, we study how atmospheric winds and waves in the 90-300-km height range create electric fields. The processes discussed here dominate the earth’s electric field below 60° latitude. The phenomena discussed in Chapters 4 and 5 dominate above this latitude. In each case, the key diagnostic equation is that the divergence of current must vanish—basically Kirchhoff’s Current Law from electrical circuit theory and conservation of charge from a physics viewpoint. In Section 3.2, we discuss the motion of the dense neutral upper atmosphere and how its interaction with the plasma creates electrical currents. For these currents to be divergence-free, electric fields must exist, and we provide some simplified models that predict the magnitude and direction of these fields. To proceed further, we need a better understanding of these atmospheric motions, which are better characterized by the terms “tides” and “internal waves.” After this discussion, we examine how such waves can generate electric fields and other issues relating to the earth’s electric field.