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The existence of infrasonic pulses induced by lightning within thunderclouds is now firmly established from experimental observation. The observed waveform has a compressive pulse followed by a rarefactive pulse. This is of opposite polarity to that predicted by pre-existing theories. This thesis presents a version of a previous theory modified to explain the difference in polarity. It is shown that these infrasonic pulses are wholly electrostatic in origin and arise out of the interaction of the large space charges inside thunderclouds. The positive part of the pulse is due to the relaxation of the mutual attraction of the negative charge layer and the positive shielding layer beneath it during a lightning event. The negative portion of the pulse is due to the reduction in the mutual repulsion of the charged cloud particles in the negative charge storage layer. A series of calculations, done with spherical charges, is presented that describes the changes in the electrostatic potential energy in a simple thundercloud as the result of the partial neutralization of the stored charge by a lightning flash. These calculations are used to demonstrate that two competing theories, ohmic heating of the air within the charge storage region and rapid charge separation, cannot explain the amplitude of the initial positive excursion in the infrasonic waveform.

A series of 48-hour experiments performed quarterly in 1977 to study radar returns from the lower stratosphere is described. Current theories of stratospheric scatter of radio waves are presented and the radar equation pertinent to the large array at Jicamarca, Peru is derived. Observational and data reduction techniques are discussed. Experimental results concerning scattered power, mean wind velocities and velocity fluctuations are presented. It is found that isotropic turbulent scatter is not the only scattering mechanism operating in the stratosphere, and modifications to the radar equation which arise from turbulent rolls or thin layers of refractive index variation are needed. Mean winds measured by radar are comparable to those determined by rawinsonde ascent. Velocity oscillations of approximately 5-minute periods are interpreted as buoyancy oscillations with 2 km horizontal wavelength and phase velocity of 6 m/s. Tidal oscillations with periods of 24 and 12 hours are also observed. Suggestions for future measurements at Jicamarca and other institutions are offered.