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Cloud Seeding
How Does Cloud Seeding Work?
Rinkesh
The weather has
been, for Millenia, a natural phenomenon that could not be altered by human
activity.
For instance, no
one could manipulate the atmosphere so that it rains. However, in the last
several years, human intelligence and technology have changed that.
Humans can now
control the weather, including ‘making it rain’ literally – through a process
called cloud seeding.
It basically is the
enhancement of natural precipitation.
The process makes
water vapor into clouds, turning into precipitation and into rain that would
otherwise not fall on earth.
It is the most
widely used technique in the modification of weather.
The following is an
in-depth analysis of cloud seeding, how it works, and its potential negative effects.
What is Cloud Seeding?
Cloud seeding, rainmaking,
or man-made precipitation enhancement is a way to artificially modify the
weather by spreading clouds with small particles, to make it snow or rain.
In other words,
cloud seeding is all about manipulating the clouds so that it rains. Clouds
consist of water droplets or ice crystals.
They form when
water vapor in the atmosphere cools and later condenses around a particle of
dust or salt.
These dust or ice
particles, also known as condensation nuclei, facilitate the formation of
raindrops or snowflakes.
Without the
condensation nuclei, rainfall cannot form and, therefore, precipitation does
not occur.
Cloud seeding
artificially adds condensation nuclei to the atmosphere, significantly
improving the ability of a cloud to produce rain or snow.
With the added condensation
nuclei, cloud seeding provides a base for snowflakes or raindrops to form.
It, therefore,
follows that after cloud seeding, precipitation in the form of rain or snow
will fall from the clouds back to earth.
The intent or goal
of cloud seeding is to increase the rain or snow precipitation, suppress hail,
reduce lightning, or even dissipate the fog.
It is an efficient
tool, especially in arid areas of the world, where rainfall is minimal under
ordinary circumstances.
Cloud seeding has
been practiced by a number of countries including India, the United Arab
Emirates, the United States, China, and the United Kingdom.
China has used the
technology dependently in dry areas of the country.
The UAE has used
the technology since the 1990s, including in 2015 when they pumped about $5
million into their Research Program for Rain Enhancement Science.
The US has employed
the technology since the 1950s, especially in the Rocky Mountains,
Sierra Nevada, and other mountainous and dry areas.
During the 2008
Beijing Summer Olympics and during the wedding of the Duke and Duchess of
Cambridge, the technology was used to prevent rain.
How Does Cloud Seeding Work?
The enhancement of
rainmaking or precipitation was first done in 1946 when Vincent Schaefer and
Bernard Vonnegu, American scientists at General Electric, were successful in
seeding a cloud with dry ice.
They climbed onto a
small plane and seeded a cloud with dry ice floating above Schenectady, New
York. They then watched as the snow fell from the base of the ice.
After that
experiment, Schaefer became referred to as the ‘Snow Man’. According to Guo
(2018), three methods can make cloud seeding work:
1.
Spraying water into warm clouds
2.
Dropping ice into cold clouds
3.
Spraying silver iodide or similar crystals into a cold cloud,
either from the ground or over the cloud from an airplane
Regardless, the
types of clouds play a vital role in ensuring the process is successful.
Large droplets are
required if rain is expected to form, meaning maritime clouds are a better
source of rain than continental clouds.
The temperature of
the cloud is also important.
For instance,
cumulus and stratiform clouds, whose temperature is below -7°C, would be
accompanied by precipitation within 25 minutes.
Types of Cloud Seeding
1. Static Cloud seeding
This first of three
methods work when a chemical compound is spread onto the clouds.
It is the most
commonly used method and involves the spraying of particles of salt, like
silver iodide and chloride onto clouds.
Silver iodide (AgI)
exists in the environment naturally and is not harmful to humans or wildlife.
To do so, a special
aircraft, rocket, or other dispersion device is used.
The salt particles
act as a condensation nucleus, drawing water vapor within the cloud towards
them.
Moisture will then
latch onto them, condensing into water droplets. Subsequently, raindrops form,
leading to rainfall.
2. Dynamic Cloud Seeding
This second type of
seeding works by boosting the vertical air currents, encouraging more water to
pass through the clouds.
It, therefore,
translates to more rain.
For it to work,
about 100 times more ice crystals are required as compared to the static cloud
seeding method.
It is a more
complex method as it relies on a sequence of events working properly.
Scientists within
the atmospheric science departments as well as other researchers have broken
the dynamic cloud seeding method
into eleven separate stages.
If one of the
stages fails or its outcome is unexpected, the entire process is ruined.
It also makes the
technique less dependent as compared to the static cloud seeding method.
3. Hygroscopic Cloud Seeding
This last type
utilizes the dispersal of salts through flares or explosives onto the lower
parts of a cloud.
The salt will
become bigger and water will join it.
It is a relatively
new method that has been described as ‘promising.’ It, however, requires more
research.
Negative Effects of Cloud Seeding
1. The process is not 100% effective
Despite the process
being touted as highly successful in creating rain, it has raised concerns as
to its actual effectiveness.
The main question
that arises is, would rain have come in a certain place even without the need
for the seeding?
Cloud seeding
becomes irrelevant if it would have rained regardless of it being used.
It becomes
difficult to ascertain if fluctuations in the level of rainfall, occurring
during cloud seeding times, are produced by seeding or could have occurred
naturally.
2. The process is very expensive
It is an innovative way of
creating rainfall, especially in arid areas. However, it is an expensive
process.
In China, for
instance, the country uses between $60 and $90 million every year on such
weather modification projects.
Between 1995 and
2003, the country used $266 million for the same causes.
As already
mentioned, the UAE spent about $5 million in 2015 for its Research Program for
Rain Enhancement Science.
Such monies could
be used to fund other projects, given that it will inevitably rain.
Also, if the aim is
to bring rain to areas severely affected by climate change,
wouldn’t it be easier to tackle global warming and climate change, as it would
bring a long-lasting solution?
3. The truth about silver iodide is that it may potentially
contain dangerous substances
Despite silver
iodide being termed as safe for the environment, there remain concerns about
exposure to the same, especially with regards to soil contamination.
Silver iodide has
been known to result in incapacitation and possible residual injuries to humans and other animals,
especially after chronic exposure.
The toxicity of
silver and its compounds in the environment might be low, but they are negative
effects nonetheless.
4. Cloud seeding is not the end solution; it may actually
worsen global warming and climate change
It has been argued
that cloud seeding is just a way of sweeping the effects of pollution and
climate change under the rug.
Using cloud seeding
to bring rainfall does not negate the fact that climate change exists
and the process does nothing to fix the initial problem, which is global
warming and climate change.
Since the process
is expensive, it would be easier to fix the bigger problem and enjoy the
long-term benefits of a better climate.
5. The results might be damaging – more or less rain!
The end results of
cloud seeding are either having no rain, like during the 2008 Beijing Olympics
or having more rain, especially in dry areas.
However, sometimes,
the results have been damaging.
In 1974, a
hurricane on the US East Coast was seeded using dry ice.
The hurricane did
not hit the area but moved to the west in Georgia. It caused severe damage,
leading to General Electric Corporation being sued.
Operation Cumulus
was as well an alleged to be series of secret scientific experiments being
conducted in the UK between August 4th and 15th What followed were flash floods in Devon
village in Lynmouth, England, killing 35 people.
6. Cloud seeding can be used for destructive purposes
According to Brown
(2018), only 56 countries practiced cloud seeding activities in 2016.
This means the
possibility of more powerful countries using the process to attack other
countries.
For instance, the
US used cloud seeding to cause a monsoon in Ho Chi Minh, Vietnam, during the
Vietnam War, as a tactic against the Vietnamese soldiers.
Rinkesh. A true environmentalist by heart ❤️. Founded Conserve
Energy Future with the sole motto of providing helpful information related to
our rapidly depleting environment. Unless you strongly believe in Elon Musk‘s
idea of making Mars as another habitable planet, do remember that there really
is no 'Planet B' in this whole universe.
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