Making rain?

Well, my brother recently showed me this news story about them making it rain in Beijing to clean the city. I don't have the exact link anymore so i'll just give you the story. From ninemsn news. I don't know if this has been used before...but if it has delete away.

Artificial rain washes dust from Beijing
Friday May 5 19:50 AEST

Chinese technicians have artificially generated heavy rainfall to wash a layer of sand and dust off Beijing, the official Xinhua news agency said.

The Chinese capital was hit by a fierce wind storm last month which left the city cloaked in sand, much of it scooped up from the Gobi desert.

The Beijing Weather Modification Office responded with a major cloud seeding operation.

"A total of 163 pieces of cigarette-like sticks containing silver iodide were burnt and seven rocket shells were launched in six districts and counties, which resulted in the heaviest rainfall in Beijing this spring," Xinhua said.

Although the science of weather seeding is controversial and some doubt its effectiveness, China often seeds clouds in an effort to end droughts in the arid north.


Anyway, I just wanted to know in greater detail how it works, and the enviromental effects of them doing it. Silver iodide cant be good for the ground.

No matter how much rain-making they can accomplish, I have read about the Asian deserts, and how their size had increased unprecedented amounts last century due to human tampering, and how once fertile farm lands are now buried under metres and metres of unmovable sand. All this has something to do with more erratic wind patterns and the warming of the planet a few degrees every 10 or so years and all that. Can't remember properly now; but this rain thing would only be a quick-fix, like putting a band-aid on a compound fracture. In the end, it's just not going to work.

If this truly can be done one most ask the question, why isn't the US doing it over the parched areas of the country that are on fire? Surely there are large economic impacts at this point by the droughts affecting the country.

Is it because we don't have the technology, there are side affects that are incosequential in China, or they just don't care?

The idea of "making rain" is quite old actually. It was first tried in the 1940's and is actually called "cloud seeding".

In short it works like this:

silver iodide flares will be ignited as an aircraft flies through a cloud. When released by devices on the ground, air currents may pull the fine particles up into the air. These chemicals provide a nucleus for moisture in the cloud to form around (heterogeneous nucleation), which in turn will usually cause the precipitation to increase from the clouds or cause the clouds to become less dense.

Much more on Wikipedia!

it just goes to show that silver iodide has a lot of uses - many still left to be discovered...

Interesting enough - Beijing "fires" silver iodide rockets when "rain is desired". This causes political issues as neighboring regions complain that Beijing is "stealing" their rain.

This sites may also interest you:
www.weathermodification.org...
www.hydro.com.au...
www.lightwatcher.com...

You could also try the Zulu method of “making rain” by doing a rain dance…

Edit: Added links

[edit on 8-5-2006 by Gemwolf]

Yup, as said, cloud-seeding has been around for awhile. I remember it being done before.

Why isn't it done more often? It's a bit expensive, and its not 100% reliable. Imagine spending $10,000 for something that didn't work.

As for how it works, from what I can remember they "seed" the clouds by dusting the air. The tiny particles in the air then attract moisture. Since you seed an area, this moisture becomes a cloud, and then continues until it rains.

There's probably more to it than that (the type of material used to seed the clouds is probably some kind of chemical that easily attracts moisture), it might not always be able to be used - especially if it's, say, windy, and the wind blows the rain clouds away.