Scientist creating rain-making lasers, Rhone river Swiss

Published
30 August 2011

A team of researchers at the University of Geneva is coming ever closer to creating real-deal downpours by shooting beams from their laser system into the sky above the Rhone River.

While logging nearly 133 hours between the fall of 2009 and spring of 2010, the team observed that the beams actually triggered the creation of nitric acid particles, which bound water molecules together creating water droplets.

Those droplets proved too small and light to actually be categorized as rain, but the discovery has apparently spurred the scientists on. Previous efforts to make it rain, known as seeding, have used rockets and jets to shoot silver iodide and dry ice into the sky.

Hope this discovery be used only for good purposes, but I don't like it when scientists are still playing too mach specially with whether.

Because of the potential impact on agriculture and other key human activities, efforts have been dedicated to the local control of precipitation. The most common approach consists of dispersing small particles of dry ice, silver iodide, or other salts in the atmosphere. Here we show, using field experiments conducted under various atmospheric conditions, that laser filaments can induce water condensation and fast droplet growth up to several μm in diameter in the atmosphere as soon as the relative humidity exceeds 70%. We propose that this effect relies mainly on photochemical formation of p.p.m.-range concentrations of hygroscopic HNO3, allowing efficient binary HNO3–H2O condensation in the laser filaments. Thermodynamic, as well as kinetic, numerical modelling based on this scenario semiquantitatively reproduces the experimental results, suggesting that particle stabilization by HNO3 has a substantial role in the laser-induced condensation.

Owing to their impact on key human activities like agriculture, strong efforts have been dedicated in the last 70 years to seed clouds by dispersing small particles of dry ice, AgI, or other salts in the atmosphere1. However, the efficiency of these techniques is still debated2, 3. Recently, self-guided ionized filaments4, 5, 6, 7, 8, generated by ultrashort laser pulses, have been proposed as an alternative approach to trigger water condensation9.

Here, on the basis of field experiments performed under various atmospheric conditions, we show that laser filaments can induce water condensation and droplet growth up to several μm in diameter in the atmosphere as soon as the relative humidity (RH) exceeds 70%. We propose that the local photochemical formation of p.p.m.-range concentrations of hygroscopic HNO3 substantially contributes to this effect by enabling efficient binary HNO3–H2O condensation in the laser filaments. Thermodynamic as well as kinetic numerical modelling supports this interpretation. These results offer key information to optimize the water condensation process.

www.nature.com...

I wish the dates of experiments were included in there, just out of curiosity! I live along the Rhone (further down, in France though) and we had a very uncommon rain event recently, either the 30th or the 1st, in which a sudden and unexpected outpour came on. Such summertime showers are not uncommon... what was uncommon was the length (went on for more than an hour) and the STRENGTH of the downpour! I have never seen such a thing! I had to run outside to get a backpack one of my kids had dropped in the driveway, and even with a big jacket covering myhead and body, the rain almost hurt, as if I had a huge heavy pool being dumped on my head. I couldn't see a thing, and the damage it did to our property was extensive.

Then yesterday we had another replay of that.

If these experiments are being done around here, they really should find another area to do it! I live at a high altitude, but all along the Rhone, many villages are in great danger of flooding when there is much rain and people lose their homes.

reply to post by Bluesma


Rain event ? I think you need a word with Mr Carlin (Rest in peace old man)

www.youtube.com...

However, this is a serious matter. It is very important that these scientists ensure that they have control over ALL effects of thier work, and take responsibility for any negative outcomes of thier experiments. That said that if this idea can be shown to work over drought areas, like Sudan , Chad, and Somalia, then the people there would be an awful lot better able to look after themselves, which is , honestly speaking, what they want, and what the rest of us want for them .

If it works they could make it rain in places where there is no rain for the people to plant seeds and grow food