Cloud seeding analysis from India

1. Cloud Seeding
Soumyajit Basu

2. What is Cloud Seeding?
The introduction of artificial substances (usually silver iodide or dry ice) into a
cloud for the purpose of either modifying its development or increasing its
precipitation.
The attempt to change the amount or type of precipitation or the structure of
clouds by dispersing substances into the air which allow water droplets or ice
crystals to form more easily. The most common chemicals used for cloud
seeding are silver iodide and dry ice.

4. Why do we use it?
• By the year 2025 two thirds of the world population will
live under severe water stress conditions as
determined by studies of the World Meteorological
Organization (WMO)
• The rapid growth of Agricultural and Industrial sector
along with the population explosion makes India
particularly vulnerable.
• Though India get high amount of rainfall compared to
many other countries, the large infrastructure and
water intensive agricultural practice makes India
vulnerable to even to the minor swings (< 5%) in
rainfall
• Water related problems within the states

6. Cloud Seeding
• Cloud seeding is actually a very complex process. In the simplest
terms, it introduces other particles (CCN’s) into a cloud to serve as
cloud condensation nuclei and aid in the formation of precipitation.
There are three types of cloud seeding: static mode, dynamic mode, and
hygroscopic seeding.
• Static mode cloud seeding seeks to increase rainfall by adding ice
crystals (usually in the form of silver iodide or dry ice) to cold clouds.
• Dynamic mode cloud seeding increases rainfall by enhancing "vertical
air currents in clouds and thereby vertically process more water through
the clouds." Basically, in this method of seeding, a much larger number
of ice crystals are added to the cloud than in the static mode.
• In hygroscopic seeding, salt crystals are released into a cloud. These
particles grow until they are large enough to cause precipitation to form.
Clouds can be seeded from above with the help of airplanes that drop
pyrotechnics, or from the ground by using artillery or ground-to-air

7. 20.32microns
76.2 microns
5080microns
= 0.5cm
5080microns
= 0.5cm

8. Cloud Seeding
Depending on the preciitation cloud seeding can be divided into
2 types-
(i) Warm Cloud Seeding(water drops)
(ii) Cold Cloud seeding(ice crystals)

9. Technologies Required
Cloud seeding requires advanced equipment and
facilities including-
1) Aircraft
2) A meteorological station network to monitor the
clouds,
3) A rainfall monitoring ground network
4) A network for data collection and processing,
5) A satellite image transmission networks.

10. Silver Iodide
• Why Silver Iodide ?
– It has a crystalline structure similar to ice crystal, and it acts as an
effective ice nucleus at temp. of -4°C and lower
– Silver iodide, when burned, creates extra ice crystals in winter
clouds to increase snow fall. (The first AgI generator could
discharge 1016 particles per gram)
It can be distributed from the ground...

11. Silver Iodide
…or from the air.

12. Ground based Generator Automated High-Output Ground Seeding System
Aircraft-mounted flares
Cloud Seeding Aircraft

15. TITAN
• TITAN means Thunder storm Identification Tracking
Analysis and Now-casting
• It is a software developed for forecasting and analysis of
thunder storms in weather modification programs
• TITAN gives 10 derived parameters of the cloud giving a
scope to find latitude and longitude and cross sectional
view of the clouds at any instant.
• The cloud parameters given by the TITAN are given as
Area, Volume, Mass, Precipitation Flux, Vertical Integrated
Liquid Content etc.,
--shown in next slide

16. 1) Area (km2) : Area (km2) covered by the cloud, it is the value of horizontal spread up of the
cloud as observed by radar
2) Volume (km3) : Volume (km3) of the cloud, it is the value of the volume occupied by the cloud as
observed by radar
3) Mass (k tons) : Mass (k tons) of the cloud, it is the value of the mass contained by the cloud as
observed by radar
4) V I L (kg/m2) : Vertical Integrated Liquid content (kg/m2) of the cloud, it is the value of the
vertical integration of liquid matter present in the cloud as observed by the
radar
5) P-flux (m3/sec) : Precipitation flux of the cloud, it is the value of the flux of mass ( Precipitation)
falling down from the cloud as observed by the radar
6) Max- Z (dbz) : Maximum reflection of the cloud, it is the value of the maximum reflection of
the cloud as observed by the radar. Reflection depends on the type of the matter
present in the cloud, basically if the matter if the matter present in the cloud is
more, the reflection of the cloud will be more
7) Ht-maxZ (km) : Height of maximum reflection of the cloud, it is the value of the height from
which maximum reflection is coming from the cloud as observed by the radar.
8) Centroid (km) : Centroid of the cloud is basically known as the centre of gravity of the cloud, it
is the height at which the total weight of the cloud is said to be concentrated as
observed by the radar
9) Cloud Base (km) : Cloud Base is the height of the bottom part of the cloud from the earths surface
as observed by the radar
10) Cloud Top (km): Cloud Top is the height of the top most part of the cloud from the earths surface
as observed by the radar

17. Target and Control Method
• By using TITAN software we can compare
various parameters of Seeded and
Unseeded clouds which is known as
“Target and Control method”
• In the Target and Control method
Target means the Seeded cloud
and the
Control means the Unseeded cloud.

18. TITAN images of the CLOUDS on AUGUST
11,2008

23. Control Cloud 137
Target Cloud 136/147
Control Cloud 134
Control Cloud 133

28. Seeding of Target Cloud 136/147

33. Advantages
• It contributes to augmenting freshwater resources to meet water
demands, particularly in arid and semi-arid regions. It holds
promise for regions facing water deficiencies. Its efficiency can be
increased through research, experiments, and a better
understanding of precipitation and cloud systems;
• Cloud seeding can contribute to increasing shallow underground
storage water;
• It allows successful dissipation of fogs and low stratus clouds that
can be an obstacle to aviation traffic at airports;
• It contributes to improving the productivity of rain-fed agricultural
areas, either by increasing rainfall volumes or sometimes by
controlling the spatial and temporal distribution of rainfall.

34. Disadvantages
• The disadvantages of this technology are as follows:
• The effectiveness of this technology in drought situations is very limited,
primarily due to inappropriate climatic conditions during such periods;
• Positive benefits from a cloud-seeding process for one group of a
community may be accompanied by negative effects on other groups;
• For countries of limited areas, or along national boundaries, cloud seeding
could result in problems relating to possible negative effects that might
occur in neighboring countries. Cooperation in such cases is therefore
essential, and may require issuance of legislation regulating the legal
aspects of cloud seeding;
• Cloud seeding requires advanced and costly equipment, as well as the
recording, collection and analysis of relevant information. The seeding
process also required qualified professional staff and modern equipment.
Thus, the benefits may ultimately not be sufficient to cover the costs. A
cloud-seeding program also will not produce effective results without
accurate weather data, or an inability to carry out the seeding process at
the suitable time or place;
• Although planning of cloud-seeding programs may be successfully and
efficiently carried out, accurate and practical assessment of the results
may be hindered by the lack of physical and statistical evidence. The
assessment process also may require the use of modeling techniques.

35. Cloud seeding operations-2008
25 Jul – 24 Nov 08 (120 days)
District
No.of
Seedings
Hygro's
(1 Kg)
Hygro's
(0.5 Kg)
ANANTAPUR 83 72 21
CHITTOOR 55 44 16
GUNTUR 0 0 0
KADAPA 76 71 16
KARIMNAGAR 7 7
KURNOOL 64 64 10
MAHABUBNAGAR 105 102 21
MEDAK 11 13
NALGONDA 35 35 8
NELLORE 8 5 5
PRAKASAM 16 10 12
RANGA REDDY 24 28 3
Total 484 451 112
12 Districts

36. Thank You