As wind blows air over a mountain or other obstacle air is forced upwards and gravity forces it back down. This generates a wave in the atmosphere called a “gravity” wave. The wave amplitude of a such a vertically propagating wave can increase with altitude because air density decreases with height. The increased energy in the wave can exceed the local speed of sound and result in a broken crest as shown in the photograph above. Cosmic ignited plasmas in the atmosphere can be heated by microwaves and generate gravitational waves.
There is some indication that HAARP may be generating them now. (See Penn State Lecture below)
COSMIC IGNITION WEATHER MODIFICATION TOOLS
The plasma formed in the atmosphere using the cosmic particle ignition methods can be used for weather research and weather modification in a number of ways. The plasma can act as a heater. It can be designed to have energy deposited in the air. This energy can be used to heat water droplets in the case of tornado modification or to generate acoustic and gravitational waves by heating the atmosphere and modulating the heating rate by
modulating the power of the heating beam. The heating can be applied to specific portions of a hurricane and potentially modify its strength or direction.
For more go here: http://eastlundscience.com/CIPPAWEATHER.html