Native American Indians have developed across centuries a rain dance (look at the clip for a bit of culture and fun) that was supposedly effective in bringing rain to an area. I can understand if you are a bit skeptical about its effectiveness ...
Anyhow, the need for rain is still present in our world in many areas. How many times we see clouds that are rich with water simply flying over dry fields and wished we could have a way to turn on a switch and have rain falling down.
Rain happens when "seeds" form in cloud, tiny aggregation that in turns pull water molecule together to the point where they can no longer float in the cloud and have to come down in droplets - i.e. rain.
Now researchers at the University of Central Florida College of Optics and Photonics in cooperation with colleagues at the Arizona University have worked out a method that for the non-initiated looks as esoteric as the Native american rain dance. This one is based on strage properties of laser beams.
It was already known that beaming a high energy laser beam into a dense water molecules environment (like a cloud) stimulates condensation (water droplets). The problem is that a high energy beam laser rapidly collapses on itself thus traveling for very few meters only (it will not reach the cloud...). Indeed a laser beam, that we have learned to travel amazing distances without losing its power (recently we have seen a proposal, and experiments, to use laser beams to connect spacecrafts with Earth base stations supporting high speed communications) once reaches certain energy thresholds starts to collapse and this in turns strips electrons out of oxygen and nitrogen molecules creating a plasma. The plasma interacts with the collapsing laser beams forcing it to disperse into filaments (the process is called filamentation), light strings that disperse in space.
Now the researchers have found a way to maintain the high energy beam by surrounding it with a second laser beam that basically stabilises it. This second beam behaves like a ring around the high energy beam extending its reach.
So far the extension has been limited (from 10" to 7') but researchers feel they can extend it much further to reach the clouds. The filaments would create the required charged static particles that will work like the seed needed for condensation.
Now this will really provide an interesting tool for many farmer to get rain. Of course, it will potentially create new matter for arguing, like todays management of river water leads to strong dispute among Countries. Imagine commanding a cloud to pour its water reservoir on this Country .... no more left for the Country that would have been on the cloud path...