Please google this topic?
We have been able to modify rainfall, by creating storms, for over 50 years. 4 persons were killed in Cornwall in UK, in 1954 or so, by artificially created storm. The efficacy surprized the scientists.
All member countries of ANZUS are restricting publication of scientific and technical advances if they have war weapon potential!
HAARP is a civilian research facility, based upon this science. It can spot warming that is artificially caused. To warm air, we zap it and the water it contains, with microwave EM radiation. RADAR uses this for detection of movement even as far as China, from Australia! The amounts of energy require a small nuclear reactor at Pine Gap.... OTH, stands for over the horizon, radar is well known but can be used only against the country of the operator, as otherwise it is an act of war!
Warming the atmosphere causes the air to rise, sucking in new air which then also rises. Vortices are then formed which will cause deposition of the warmed water, once the vortex reaches self sustaining energy levels that drag warmed air back down to the lower altitudes where the water reaches the dew point!