Cloud seeding involves introducing substances like silver iodide or dry ice into clouds to encourage the formation of rain or snow. It has been practiced since the 1940s to increase rainfall and benefits agriculture. However, it is an expensive technique and chemicals used can potentially damage the environment. While it has helped boost crop yields in drought-prone areas, it also carries risks like flooding if not implemented properly. Major projects have included Stormfury to weaken hurricanes and Operation Popeye during the Vietnam War to extend the monsoon season.

1. PRESENTATION ON
“ Importance and utility of cloud seeding in
agriculture ”
PRESENTED BY
KHILESH KUMAR SAHU
DEPT. OF AGROMETEOROLOGY
Course Title:- Master Seminar
Course No:- 591

2. Contents :-
• History of cloud seeding
• Cloud seeding and Principles of rainmaking
• Methods of cloud seeding
• condition For successful artificial rains
• Advantages and Disadvantages of Cloud Seeding
• Project stromfury
• Operation Popeye
• Conclusion

3. History of cloud seeding
• In the late 1940’s Langmuir and his general electric research
laboratory discovered that dry ice when dropped into super cooled
cloud deck from an air plain, caused a rapid conversion of water to
ice leading quickly to the other production of snowflakes and
dissipation of clouds in the region seeded
• 1951 – Tata farm over western Ghats using ground based silver
iodide generator.
• 1957 -1966 national physical laboratory (NPL) experiment using
ground based generator ,in north India.
• 1973-1974,1976 and 1979-86 IITM, experiment with cloud
seeding shows 24% increase in the rainfall.

4. • 1990-2000 witnessed many advances in the air born instrumentation
radars, flares and software. They got imported to India in new
millennium
• 2003 Karnataka government has initiated cloud seeding with modern
Gadztes like radars and aircraft in Maharashtra government fallowed a
month later.
• 2003- 2009 Andhra Pradesh govt. has conducted cloud seeding
operation the longest & biggest programme in south east Asia.

5. Cloud seeding:- Cloud seeding is one of the tools to mitigate the effects
of drought. It is defined as a process in which the precipitation is
encouraged by injecting artificial condensation nuclei through aircrafts or
suitable mechanism to induce rain from bearing cloud.
Principles of rainmaking :-Clouds are classified into warm and cold
clouds based on cloud top temperature.
•If the cloud temperature is positive these clouds are called warm clouds
and if it is negative they are called as cold clouds.
•The nucleus needed for precipitation differs with type of clouds.
Hygroscopic materials are necessary as nucleus for warm clouds.

6. Seeding of cold clouds This can be achieved by two
ways (1. Dry ice seeding and 2. Silver Iodide seeding).
• Dry ice seeding
• Dry ice (solid carbon-dioxide) has certain specific features. It
remains as it is at –80˚C and evaporates, but does not melt. Dry
ice is heavy and falls rapidly from top of cloud and has no
persistent effects due to cloud seeding.
• Aircrafts are commonly used for cloud seeding with dry ice.
• Aircraft flies across the top of a cloud and 0.5 – 1.0 cm dry ice
pellets are released in a steady stream.
• While falling through the cloud a sheet of ice crystals is formed.
• From these ice crystals rain occurs.

7. Silver Iodide seeding :-
In seeding cold clouds silver iodide technique is more useful than dry
ice techniques, because, very much less of silver iodide is required per
cloud.
How it Works :-Cloud seeding involves the use of water-absorbent
materials to encourage the formation of clouds and rain so that there
could be increased crop production in areas where there's little water

8. Seeding of warm clouds
• 1) Water drop Technique :-Coalescence process is mainly
responsible for growth of rain drops in warm cloud. The basic
assumption is that the presence of comparatively large water
droplets is necessary to initiate the coalescence process. So, water
droplets or large hygroscopic nuclei are introduced in to the cloud.
Water drops of 25 mm are sprayed from aircraft at the rate of 30
gallons per seeding on warm clouds.
• 2) Common salt technique :-Common salt is a suitable seeding
material for seeding warm clouds. It is used either in the form of
10 per cent solution or solid. A mixture of salt and soap avoid
practical problems. The spraying is done by power sprayers and
air compressors or even from ground generators. The balloon burst
technique is also beneficial. In this case gunpowder and sodium
chloride are arranged to explode near cloud base dispersing salt
particles.

9. For successful artificial rains, the following condition are
necessary.
• Presence of cloud particles in large amounts in super cold
condition.
• Large spread of clouds
• Upward movement of clouds with spread.
• Unstable condition on earth’s surface to accelerate the process
of cloud formation.

10. Advantages of Cloud Seeding
• This technique is used to produce the clouds and bring rain to
the draught prone areas for better rain and boosting crop yield.
• It is also used to reduce the size of hailstones where hail stones
precipitate in large size
• It is also used on some airports to reduce fog which has always
been a cause of mishaps on airports
• This technique is used to clear the air in the fields during
matches or concerts.
• Where there is rain, there is farm produce. Farms that yield
better can help the local economy and feed the people (and
even animals). Cloud seeding can greatly improve the living
conditions in dry, arid places.
• Rain is important for keeping the area hydrated and fertile for
growing crops and other plants.

11. Disadvantages of Cloud Seeding
• Chemicals used in cloud seeding can potentially damage the
environment and Silver iodine may cause “iodism,” a type of
iodine poisoning where the patient exhibits running nose,
headache, skin rash, anemia, and diarrhea, among others
• It is very expensive to produce artificial rain.
• If not regulated or controlled properly, cloud seeding may
cause undesirable if not altogether destructive weather
conditions such as flooding, storms, hail risks, etc

12. Project stromfury
•Project Stormfury was a research program for hurricane modification
that was active between 1962 and 1983.
•The Stormfury hypothesis was that seeding the first rain band outside of
the eyewall clouds with silver iodide (AgI) would cause supercooled
water to turn into ice.
•The artificially invigorated convection, it was argued, would compete
with the convection in the original eye wall, lead to reformation of the
eye wall at larger radius, and thus produce a decrease in the maximum
wind Since a hurricane's destructive potential increases rapidly as its
maximum wind becomes stronger, a reduction as small as 10% would
have been worthwhile.
•Modification was attempted in four hurricanes on eight different days.
On four of these days, the winds decreased by between 10 and 30%.
•The lack of response on the other days was interpreted to be the result of
faulty execution of the experiment or poorly selected subjects.

13. .
Operation Popeye
Operation Popeye (Project Controlled Weather Popeye / Motorpool /
Intermediary-Compatriot) was a highly classified weather
modification program in Southeast Asia during 1967–1972. The cloud
seeding operation during the Vietnam War ran from March 20, 1967 until
July 5, 1972 in an attempt to extend the monsoon season, specifically
over areas of the Ho Chi Minh Trail. The operation was used to induce
rain and extend the East Asian Monsoon season in support of U.S.
government efforts related to the War in Southeast Asia .
Objectives:-
Operation Popeye's goal was to increase rainfall in carefully selected
areas to deny the Vietnamese enemy, namely military supply trucks, the
use of roads by:-
Softening road surfaces
Causing landslides along roadways
Washing out river crossings
Maintaining saturated soil conditions beyond the normal time span

14. Conclusion :-
• Cloud seeding is the costly process to be practice
normally under normal situation but it can be
effective under emergency situation.
• It can be use for rain making hail storm reduction ,fog
suspension,harrican modification etc.
• It useful in agriculture and also harmful like Silver
iodine may cause “iodism,” a type of iodine
poisoning where the patient exhibits running nose,
headache, skin rash, anemia, and diarrhea, among
others .