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Make it Rain
Wouldn't it be nice to change the weather? Well,
it might surprise you to know that scientists and meteorologists have
been doing just that since the 1940s. The technique is called cloud
seeding, and it involves releasing 'seeds' in the form of silver iodide
into the atmosphere to encourage the formation of clouds.
How are clouds formed in the first place?
Clouds appear when evaporated water molecules
condense around dust and ice. This is known as a nucleus. As more and
more of these water droplets collect around the nucleus, larger droplets
collide and begin to form clouds. This natural seeding is what
scientists have been able to copy. They do this by shooting flares from
airplanes or even by sending up rockets into the air.
This process isn't possible if there is no water vapour or small clouds
in the area to begin with. There needs to be a catalyst to encourage
clouds to form.
Why do it?
There are many dry places on earth that need a
rainfall boost. For example, the United Arab Emirates (UAE) is one of
the driest countries on the planet. It gets a mere 120 millimetres of
rainfall each year, on average. In order to grow anything, cloud seeding
programmes are essential in such areas.
Cloud seeding is not only used for agricultural purposes. It was put
into practice in China before the 2008 Beijing Olympics to make sure
there were blue skies above the games. It can also help to prevent
extreme weather conditions such as hail storms.
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