“The first
attempt to modify natural clouds in the field through "cloud seeding"
began during a flight that began in upstate New York on 13 November 1946.
Schaefer was able to cause snow to fall near Mount Greylock in western
Massachusetts, after he dumped six pounds of dry ice into the target cloud from
a plane after a 60-mile easterly chase from the Schenectady County Airport.” -American
Meteorological Association
The above
quote is about the earliest generally known modern approach to rain making, now
referred to as Cloud Seeding.
WHAT IS RAIN MAKING (CLOUD
SEEDING)
Cloud seeding is a type of weather
modification that aims to change the amount or type of precipitation that falls
from clouds by dispersing substances into the air that serve as cloud condensation
or ice nuclei, which alter the microphysical processes within the cloud. The
usual intent is to increase precipitation (rain or snow), but hail and fog
suppression are also widely practiced in airports where harsh weather
conditions are experienced.
The above is a definition from the world accepted online
dictionary, Wikipedia
GENERAL PERCEPTIONS ABOUT RAIN MAKING
I preferred to take off from the
above two stand points to enable all of us come onto the same platform for a
better understanding of this phenomenon. In most places in the black continent
of Africa, South America, the red Indians, Europe, the Middle and Far East, and
modern Americas, there is a general knowledge about the art and science of rain
making.
I can vividly recall seeing my
maternal grandfather bring out a certain heavy stone that glistened in the Sun.
He did this whenever it threatened to rain. In most instances the rain never
fell. He had even taken this stone along if he felt the rain might disturb his
mission. However there been this effort in the general every day discourse to
play down the reality of this fact of life.
SCIENTIFIC EFFORTS TO UNDERSTAND RAIN MAKING
In 2003 the US National Research
Council (NRC) released a report stating, "...science is unable to say with
assurance which, if any, seeding techniques produce positive effects. In the 55
years following the first cloud-seeding demonstrations, substantial progress
has been made in understanding the natural processes that account for our daily
weather. Yet scientifically acceptable proof for significant seeding effects
has not been achieved".
A 2010 Tel Aviv University study
claimed that the common practice of cloud seeding to improve rainfall, with
materials such as silver iodide and frozen carbon dioxide, seems to have little
if any impact on the amount of precipitation.
A 2011 study suggested that airplanes may produce ice particles by
freezing cloud droplets that cool as they flow around the tips of propellers,
over wings or over jet aircraft, and thereby unintentionally seed clouds. This
could have potentially serious consequences for particular hail stone
formation.
However, Jeff Tilley, director of
weather modification at the Desert Research Institute in Reno, claimed in 2016
that new technology and research has produced reliable results that make cloud
seeding a dependable and affordable water supply practice for many regions.
Moreover, in 1998 the American Meteorological Society held that
"precipitation from supercooled orographic clouds (clouds that develop
over mountains) has been seasonally increased by about 10%."
Despite the mixed scientific results,
cloud seeding was attempted during the 2008 Summer Olympics in Beijing to coax
rain showers out of clouds before they reached the Olympic city in order to
prevent rain during the opening and closing ceremonies. Whether this attempt
was successful is a matter of dispute, with Roelof Bruintjes, who leads the
National Center for Atmospheric Research's weather-modification group,
remarking that "we cannot make clouds or chase clouds away." It is
probably obvious that he was avoiding political war with some powerful nations.
From the foregoing it is
clear that the scientific community has been paying a lot of attention to the
issue of rain making and that some results have emerged.
HOW DOES MANKIND MAKE RAIN?
Louis Gathmann in 1891 suggested shooting liquid carbon dioxide into rain
clouds to cause them to rain. This is a very interesting statement. If you
have had the chance to come near where practitioners are preparing to make
rain, you must notice this heavy smoke coming from their fire place. Evidently
carbon dioxide is being produced.
During the 1930s, the Bergeron-Findeisen
process theorized that supercooled water droplets present while crystals are
released into rain clouds would cause rain. While researching aircraft icing,
General Electric (GE)'s Vincent Schaefer and Irving Langmuir confirmed the
theory. Schaefer discovered the principle of cloud seeding in July 1946 through
a series of serendipitous events.
Following ideas generated between him and
Nobel laureate Langmuir while climbing Mt Washington in New Hampshire,
Schaefer, Langmuir's research associate, created a way of experimenting with
supercooled clouds using a deep freeze unit of potential agents to stimulate
ice crystal growth, i.e., table salt,
talcum powder, soils, dust, and various chemical agents with minor effect.
Then one hot and humid July 14, 1946, he wanted to try a few experiments at GE's
Schenectady Research Lab.
He was dismayed to find that the deep
freezer was not cold enough to produce a "cloud" using breath air. He
decided to move the process along by adding a chunk of dry ice just to lower
the temperature of his experimental chamber. To his
astonishment, as soon as he breathed into the deep freezer, he noted a bluish
haze, followed by an eye-popping display of millions of microscopic ice
crystals, reflecting the strong light rays from the lamp illuminating a
cross-section of the chamber.
He instantly realized that he had
discovered a way to change super-cooled water into ice crystals. The experiment
was easily replicated, and he explored the temperature gradient to establish
the −40 °C limit for liquid water.
Within the month, Schaefer's
colleague, the atmospheric scientist Dr. Bernard Vonnegut was credited with
discovering another method for "seeding" super-cooled cloud water. Vonnegut
accomplished his discovery at the desk, looking up information in a basic
chemistry text and then tinkering with silver and iodide chemicals to produce
silver iodide.
Together with Professor Henry Chessin, Suny
Albany, a crystallographer, he co-authored a publication in Science and
received a patent in 1975. Both methods were adopted for use in cloud seeding
during 1946 while working for General Electric (GE) in the state of New York.
O lala! Ladies and Gentlemen, can you see
what is happening. Someday I will not be surprised if the local rain makers
will have to get permission from certain patent holders overseas before they
can make rain anymore.
***There is more to this issue.
However I will allow my valued reader to digest the presentations so far. A
second cut will soon appear. Thanks for your attention.***
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