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Controlling The Weather
Can China control the weather?
BY JACOB SILVERMAN & ROBERT LAMB
In
the lead-up to the 2008 Summer Olympics,
the People's Republic of China garnered
a lot of press for all its housecleaning efforts.
The
country made strides toward cleaning up pollution, revamping public
transportation and generally tidying up the city of Beijing.
After
all, the event promised to be the biggest party of the year, with the entire
world invited to tune in.
Authorities
deterred potential party crashers by making it harder to visit the city and,
yes, even requiring the visiting Luchadores to
carry permits for their trademark Mexican wrestling masks.
If
you've ever thrown a party, you too may have fretted over every detail
concerning the evening.
Will
the guests think you're cheap if you don't use the good china? Will your kids
be on their best behavior, or should you banish them to their rooms?
Chinese
officials faced similar worries heading into the summer games, only they took
their micro planning to unheard of levels.
See,
the Aug. 8 opening ceremony happened to fall during a traditionally wet season
for Beijing. To avoid any crimp in their plans, they decided to shoot down any
cloud that looked as though it might try to enter the city uninvited.
That
may sound extreme, but Chinese authorities didn't become such meteorological
control freaks overnight. Chinese research into weather control dates back to
1958.
Forty
years later, the government-run Weather Modification Program launches thousands
of specially designed rockets and artillery shells into the sky every year in
an attempt to manipulate weather conditions.
Run
by the Weather Modification Department, a division of the Chinese Academy of
Meteorological Sciences, the program employs and trains 32,000 to 35,000 people
across China, some of them farmers, who are paid to handle anti-aircraft guns
and rocket launchers [source: Aiyar].
These
heavy-duty weapons launch pellets containing silver iodide into clouds. Silver
iodide is thought to concentrate moisture and cause rain, a process known
as cloud seeding.
China
has invested heavily in this technology, using more than 12,000 anti-aircraft
guns and rocket launchers in addition to about 30 planes [source: Aiyar].
With
a population of more than 1.3 billion, China requires vast amounts of water.
The
government practices cloud seeding to try to produce rain for farmers, stave
off drought, clear away air pollution and smog, fill water basins and, of
course, produce a picture-perfect opening Olympic ceremony.
Were
Chinese authorities successful in keeping their atmospheric gatecrashers at
bay? And how does cloud seeding actually work? Read on to find out.
Cloud
Seeding Methods
The
Beijing Weather Modification
Office spent a lot of time researching how to prevent rain in the city during
the Aug. 8 opening ceremony of the 2008 Summer Olympics.
The
government even guaranteed clear skies for the event -- a promise it managed to
deliver on. The feat only took the launch of 1,104 rain dispersal rockets from 21 sites
in the city to pull off [source: O'Neill].
A
rainstorm happens after moisture collects around naturally occurring particles
in the air, causing the air to reach a level of saturation at which point it
can no longer hold in that moisture.
Cloud
seeding essentially helps that process along, providing additional
"nuclei" around which water condenses.
These
nuclei can be salts, calcium chloride, dry ice or silver iodide, which the
Chinese use. Silver iodide is effective because its form is similar to ice
crystals. Calcium chloride is often used in warm or tropical areas.
Northern China, where Beijing is
located, doesn't receive much rain -- its rainfall levels are 35 percent below
the world average, and some of its water supplies are significantly polluted.
The
area relies heavily on cloud seeding. Zhiang Qiang, who runs the Beijing
Weather Modification Office, told the Asia Times that water levels in Beijing's
water basins have increased up to 13 percent due to cloud seeding [source: Aiyar].
Cloud
seeding also has been used to cool Beijing on hot days.
There
are three cloud seeding methods: static, dynamic and hygroscopic.
· Static cloud seeding involves
spreading a chemical like silver iodide into clouds. The silver iodide provides
a crystal around which moisture can condense. The moisture is already present
in the clouds, but silver iodide essentially makes rain clouds more effective
at dispensing their water.
· Dynamic cloud seeding aims to boost vertical air currents, which encourages more water
to pass through the clouds, translating into more rain [source: Cotton].
Up
to 100 times more ice crystals are used in dynamic cloud seeding than in the
static method. The process is considered more complex than static clouding
seeding because it depends on a sequence of events working properly.
Dr.
William R. Cotton, a professor of atmospheric science at Colorado State
University, and other researchers break down dynamic cloud seeding into 11
separate stages.
An
unexpected outcome in one stage could ruin the entire process, making the
technique less dependable than static cloud seeding.
Hygroscopic cloud seeding disperses salts through flares or explosives in the lower
portions of clouds. The salts grow in size as water joins with them. In his
report on cloud seeding, Cotton says that hygroscopic cloud seeding holds much
promise, but requires further research.
China
has a reputation for launching ambitious projects, from the Great Wall in
ancient times to the highest railroad in the world, connecting Qinghai to
Tibet.
But
is the investment in cloud seeding worth it, and can the government really make
it rain whenever it sees the need?
Cloud
Seeding Critics and Converts
Chinese
athletes won 51 gold medals in the 2008 summer games -- the most of any
participating nation [source: NBC].
The
Beijing Weather Modification
Office celebrated another key victory: the opening ceremony's defeat of its
dreaded adversary, the storm cloud.
The
ceremony went by without a drop, the temperature never rose above 83 degrees
Fahrenheit (29 degrees Celsius) and most of the day passed with no more than a
few scattered clouds. Impressed? Well, not everybody's sold on cloud seeding.
The United States began
weather control research in 1946. Currently, some states use cloud-seeding
programs in an attempt to increase precipitation levels or prevent
crop-damaging hail.
An
eight-year experiment in Texas and Oklahoma, conducted over
5,000 square miles (12,950 square kilometers), showed that cloud seeding
increased rainfall, cloud height, length of storms and the area in which rain
fell [source: Eckhardt].
Even
so, enthusiasm for cloud seeding in the U.S. has dried up since the early
1970s, when federal funding was about $19 million a year [source: Cotton, Engber].
Now
states have to kick in the dough if they want to try ruling the skies.
Internationally, Russia, Israel, Thailand, South Africa and Caribbean
nations have all tried their hand at cloud seeding, with mixed results.
Australian
scientists conducted numerous experiments, discovering that static seeding
didn't appear to be effective over Australia's plains but was very effective
over Tasmania.
Despite
some successful tests, cloud seeding still has many problems. The fundamental
concern is: Does it work?
It
may be a chicken-and-egg conundrum -- would it have rained in a given area
without the use of cloud seeding, and would it have rained less?
Cloud
seeding also depends heavily on environmental conditions like temperature and
cloud composition.
In
2003, the United States National Academy of Sciences declared that 30 years of
studies had not produced "convincing" evidence that weather modification
works [source: Associated
Press].
On
the other hand, the American Meteorological Society claims that some studies on
cloud seeding show a 10 percent increase in rain volume [source: Eckhardt].
Cloud
seeding is quite expensive, though potentially cheaper than other projects,
like diverting rivers, building new canals or improving irrigation systems.
Then
again, the allure of cloud seeding may redirect attention and funding from
other projects that could be more promising.
Then
there are questions about altering weather. Are some areas taking moisture out
of the air that would have fallen as rain in another region?
And
if regions are experiencing drought due to climate change, isn't effort better
spent tackling the causes of global
warming?
Despite
reassurances from cloud-seeding companies, concerns also remain about exposure
to silver iodide toxicity and soil contamination.
Other
safety issues are more transparent. In China, wayward munitions
have damaged property and even killed one person in May 2006.
The
Chinese government contends that it has improved training, licensing and safety
practices. In the end, cloud seeding has strong supporters, but it remains
controversial.
Scientists
may not be sure if cloud seeding actually works, but despite the skepticism,
China is moving forward.
The
nation spends $60 to $90 million a year on weather modification, in addition to
the $266 million spent from 1995 to 2003 [source: Things Asian].
The
government plans to produce 1.7 trillion cubic feet (50 billion cubic meters)
of rain a year through the practice [source: Aiyar].
Is
cloud seeding just a way of sweeping pollution and climate change under the rug
and playing God to ensure you don't have to schedule a rain date? Or is it
merely a matter of tweaking weather to your advantage?
However
you look at it, it's not likely to go away any time soon. In fact, scientists
have already proposed building fleets of massive, unmanned ships to seed clouds
over Earth's oceans to provide a cooling counter to carbon dioxide-induced
global warming [source: Cartlidge].
If
cloud seeding is ultimately a way to "fake it" when guests come to
visit or crops need a sprinkle, do we really want a world where we have to
manually adjust the planet's atmosphere just to stave off environmental
disaster?
About Robert
Lamb
As a
child, Robert Lamb dreamed of becoming a mad scientist when he grew up. As this
profession proved to be largely fictional, however, he swallowed his heartbreak
and turned his attention to the written word instead. He earned his bachelor's
degree in creative writing from the University of Tennessee in Knoxville, which
launched him on a career path through high school English classrooms,
small-town newsrooms and finally into the offices of HowStuffWorks.
As a
senior writer and podcaster for Stuff to Blow Your Mind, Robert
now spends his days sifting through all the scientific wonders that make the
world so mad and amazing. He currently lives in Atlanta with his lovely wife
and their beautiful one-eyed cat. When he's not researching the apocalypse or
the miracle we call a space toilet, he enjoys listening to electronic music,
painting the odd miniature and writing fiction.
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Staff
members from Beijing's Xiangshan Weather Modification Practice Base stand next
to a two-pipe cannon used for rain reduction and cloud dispersion.
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A
staff member from Beijing's Xiangshan Weather Modification Practice Base equips
a two-pipe cannon used for rain reduction and cloud dispersion with projectiles.
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Downpours
didn't snuff out the torch during the opening ceremony of Beijing's 2008
Olympic Games. Was it a matter of good luck or even better science?
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