Proposal for Water Tower Rain Generator
The engineering firm of Schlaich-Bergermann designed and built a “Solar Power Tower” in Manzanares, Spain, in the 1980s. The concept was to build a large area greenhouse and use sunlight to heat up the contained air and direct it up a tall chimney, where a wind power generator would turn the updraft into electricity. Their report is here:
https://www.sbp.de/en/project/solar-chimney-pilot-plant-manzanares/.
It, and subsequent project designs were intended to be placed in deserts or semi-arid areas, and only used for power generation.
Their New York office phone number is: 212-255-3682
However, consider if such a tower were placed over a water source, either a bay in the ocean, or a lake. The air directly over the water would be almost 100% saturated with water vapor. As air heats up, it can hold more water vapor, until at 212°F, the “air” is entirely steam or water vapor. At 38° C (100°F), it contains almost 20% water vapor, and at 62°C (140°F), it is almost 40% water vapor.
The air under the greenhouse membrane easily gets to 62°C. It can exit the chimney at more than 160 kph (100 mph), and if the top of the chimney is 20 meters across, the air exiting the chimney contains thousands of liters of water per hour.
The water vapor is also, “distilled” fresh water, no matter what the source of the water is.
Schlaich Bergermann has considered using this technology as a seawater distillation process, using condensing coils at the top of the chimney, and producing tens of thousands of liters of fresh water daily.
There is also the possibility of using it to inject these tens of thousands of liters of water into the atmosphere at a place of your choosing, and either using wind vanes, or tilting the tower, direct the plume of densely moist air in a direction.
By varying the height of the tower, and the dimensions of the aperture at the top of the tower, you can vary the speed of the resulting plume, and the distance it would travel before falling as rain.
They haven’t made a pilot project exploring the use as a water tower, but it would be reasonable to expect there would be something of a Bunsen burner effect, or Bernoulli effect, where the upwelling column of moist air would suck surrounding air along with it to magnify its effect.
It would also create a stationary, singular point low pressure area, which would create meteorological effects of its own. Along coastal waters, this would tend to bring more moist air along with it.
At first, I thought it would need to be constructed just offshore, which would be a shame along most of the coast, but then I realized that it could use an artificial lake 2 or three miles inland, and a pipeline to the ocean, and filled by a connected pipeline. A 45 hectare artificial lake (about 100 acres), 5 kilometers inland from the ocean wouldn’t be so hard to do, and the pipeline wouldn’t even need to be buried most of the way, it would just function as a siphon.
The pipeline would also be useful to turn off the rain when it wasn’t needed. When running it dry, it would continue to serve its purpose as an electrical generator.
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