Abstract
Dramatic irregularities in the plasma density of the ionosphere, first
discovered by their effects on radio wave propagation in 1938, and
despite decades of investigation, still remain puzzling. Their
deleterious effects on radio wave communication, satellite command and
control, GPS navigation are serious enough to strongly motivate better
understanding of their nature. Many aspects of such irregularities are
now understood, but the mechanism(s) of their formation and their
detailed nature remain a topic of great interest. In this work, detailed
time resolved measurements of lightning generated waves show
dispersionless, strongly attenuated propagation with substantial
propagation delays. These characteristics of the electromagnetic wave
propagation in the two-phase bubble/non-bubble ionosphere parallel the
characteristics of acoustic wave propagation through two-phase
liquid/vapor foams; and this motivates the suggestion that the
bottomside layer of the ionosphere may sometimes be foamy.