http://www.newscientist.com/news/news.jsp?id=ns99991101
Storm experts make cloud vanish
19:00 01 August 01
Marina Murphy
Storm experts in the US have made a cloud vanish from the sky for the first
time.
They achieved the feat by sprinkling a water-absorbing powder over the cloud,
making it disappear from sight and weather station radar screens. They hope
the powder will one day dry up deadly hurricanes and tropical storms.
Photo: Image State
"It is the moisture that gives hurricanes their strength," says Peter Cordani
who runs Dyn-O-Mat, the company that makes the product. "In the case of a
huge hurricane, we would not be trying to soak it up altogether. But what we
would do is break it up and reduce its strength and killing potential. We
think we can save lives with this product and we are very happy about that."
The powder could also banish rain over open-air events and sports fixtures.
Cordani and his team hope to get government permission to tackle a hurricane
or tropical storm in the coming season.
Disappearing trick
In their latest experiment, large military aircraft scattered the powder
through a storm cloud 1600 metres long and over 4000 metres deep. It took
about 4000 kilograms of powder to soak up the moisture from the cloud, making
it virtually disappear. "I had calls from a weather tower and even from
Channel 5 news in Miami, saying that they had seen the cloud literally
disappear off the radar screen. They confirmed that there had been a tall
build-up and the next moment it was gone," Cordani says.
Each grain of the powder, called Dyn-O-Gel, is capable of absorbing 2000
times its weight in moisture, condensation and rain. Each molecule of powder
can hold several molecules of water. The wet powder becomes a gel.
The shape of the grains is also crucial for maximum absorption of moisture.
"If you were to look at a grain under a microscope, it would look rather like
a cornflake," says Cordani. "This means that they flutter back and forth like
a snowflake as they pass through the cloud, taking up as much moisture as
possible. The first polymer we made just went straight down through the
cloud," he says.
Soft landing
Once the polymer turns into a gel, it becomes heavier and falls to earth. The
gel dissolves when it hits salt water, so if possible, storm clouds will be
tackled over the ocean.
But the gel should still be safe if it falls over land. "Much of the gel
evaporates on the way down, and it is biodegradable and not hazardous to the
environment or anybody's health," says Cordani. The company spent $1 million
on the test, and hopes to sell their powder to the US government.
The same powder can also be used to help make rain. The tiny flakes help bind
rain drops together, stopping them from evaporating as quickly. Once the
powder is turned into a water-laden gel you could also use it to fight fires
by dousing the flames.
So, can we have sunny days whenever we like? Maybe. "If there was a 50-mile
storm front moving in, we could only put holes in it. It would just keep
coming," says Cordani. But "if there was a cloud threatening a sports
fixture, it would be possible to get rid of it".
19:00 01 August 01
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