- Cloud seeding experiments have been conducted in India since the 1950s to enhance rainfall. The state of Andhra Pradesh has carried out extensive cloud seeding operations from 2003-2009. - Over these years, cloud seeding was conducted across hundreds of mandals using aircraft to disperse silver iodide flares into rain-producing clouds. Post-seeding verification with local officials found rainfall increases in many seeded areas. - Monitoring of the operations was done using radar stations and pilot logs to track seeded clouds and assess seeding impacts on precipitation. The results suggest that cloud seeding can effectively increase rainfall in drought-prone regions of Andhra Pradesh.

1. Experience of Cloud Seeding Operations for
Mitigation of Drought Conditions in Telangana
and Rayalaseema
CENTRE FOR WATER RESOURCES
Institute of Science and Technology
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY
E- mail: cwr_jntu@yahoo.com
coordinatorcas@gmail.com
Dr. B.Venkateswara Rao
Prof.Water Resources

2. Initial cloud seeding experiments
•In the late 1940‘s Langmuir and his Colleagues at the general electric
research laboratory discovered that dry ice when dropped into a
supercooled cloud deck from an airplane, caused a rapid conversion of
water to ice leading quickly to the production of snowflakes and
dissipation of cloud in the region seeded.
•Soon they discovered that silver iodide had same nucleating property
•Another method for stimulating the precipitation has been found by
injecting salt particles near the base of the cloud to provide centres for
droplet formations. After these discoveries many experiments have been
carried out all over the world.
•Today more than 25 countries around the globe are under taking cloud
seeding including America, Russia, china, south Africa, Australia, Canada,
Israel, Jordan, newzeland, UAE, Argentina,Thailand etc.

3. Indian History of cloud seeding
•1951- Tata firm over western Ghats using ground based silver
iodide generators
•1957-1966 National Physical Laboratory (NPL) conducted
experiments using ground based generators, in North India.
•1973-1974, 1976 and 1979-86 IITM, experiments with cloud
seeding shows 24% increase in the rain fall
•1983, 1984-87, 1993-94 Tamil Nadu Govt carried out cloud seeding
•1990-2000 witnessed many advances in the airborne
instrumentation, radars, flares and softwares.They got
imported to India in new millennium.
•2003 Karnataka Govt. has initiated cloud seeding with modern
gadztes like radars and aircrafts Maharashtra Govt.
followed a month later.
•2003-2009 Andhrapradesh Govt. has conducted cloud seeding
operations perhaps the longest & biggest programme in
south east Asia.

4. o Government of Andhra Pradesh has declared 555mandals out of 1125mandals as
Rain Shadow Areas through their Memo. No. 180/RS.V/2004-I; 22nd July
2005.This comprises an area of 1,35,680 Sq.km out of total area of 2,75,045 Sq.
km .
o The classification of Rain Shadow (RS) Mandals was done based on the mandal
receiving less than 600mm rainfall during Southwest monsoon period in
9years out of last 18years.
o Most of the RS Mandals are lying in the districts of Ranga Reddy, Nalgonda,
Mahbubnagar, Guntur, Prakasam, Nellore, Kurnool, Anantapur, Cuddapah and
Chittore districts.
o Districts like Chittore, Nellore, Prakasam, and Guntur receive rainfall during
northeast monsoon also.
o In order to enhance rainfall, dynamic seeding of clouds was taken-up in the above
RS districts during both Southwest and Northeast monsoons, with the
instructions of Hon’ble Chief Minister of Andhra Pradesh Dr Y.S.Rajasekhara
Reddy, under the Project, called INDIRA MEGHAMADHANAMU, which was
started in the year 2004.
o These programmes are regularly being monitored by Hon’ble Minister for
Agriculture, Sri N.Raghuveera Reddy and Principle Secretary of Rain Shadow Area
Development (RSAD) Department. In addition to the state level committee and
technical committee comprises several experts in the field
Rain Shadow Area Development
Department

5. Year Operating Agency Monitoring Agency
No. of Flares % of
Success
No of
Mandals
Covered in
656 Mandals
No. of C-Band Radars
Hygros BIP Eject
ables
2003
Weather Modification
Incorporation (WMI) of Fargo,
USA in association with AGNI
Aviation, Bangalore.
WALAMTARI,
Government of
Andhra Pradesh.
121 69 582
63
WEATHER RADAR,
at Jekkur Aerodrome near
Bangalore.
2004
Weather Modification
Incorporation (WMI) of Fargo,
USA in association with M/s
AGNI Aviation, Bangalore.
PanchayathRaj
Department;
Government of AP.
963 161 1436 59.6 510
Weather Radars were installed
at Karimnagar and Nandyal.
At the time of withdrawal of
Southwest monsoon,
Karimnagar Radar was shifted
to Tirupathi to study Northeast
monsoon clouds.
2005 M/s Agni Aviation, Bangalore.
Jawaharlal Nehru
Technological
University
(JNTU),Hyderabad.
457 52 185 71.7 476
C-band Radars at
Ibrahimpatnam and
Anathapur.
2006 M/s Agni Aviation, Bangalore.
Jawaharlal Nehru
Technological
University (JNTU),
Hyderabad.
200 27 15 54.4 552
Ibrahimpatnam Radar was
shifted to JNTU, Kukatpally
and with the other Radar at
Anathapur.
2007 M/s Agni Aviation, Bangalore.
Jawaharlal Nehru
Technological
University (JNTU),
Hyderabad.
547 82 -- 82 566
JNTU, Kukatpally, Hyderabad
and other Radar at Anathapur.
2008
M/s Agni Aviation, Bangalore. Jawaharlal Nehru
Technological
University (JNTU),
Hyderabad.
563 * -- --
78.2 651 JNTU, Kukatpally, Hyderabad
and other Radar at Anathapur
2009 M/s Agni Aviation, Bangalore. Jawaharlal Nehru
Technological
University (JNTU),
Hyderabad
541 -- -- 75.7 558 JNTU, Hyderabad, Anathapur
and Tirupati
History of cloud seeding operations in Andhra Pradesh

6. Philosophy behind Cloud Seeding
•Thirteenth world meteorological congress in May 1999 noted that the
weather modification for rainfall enhancement is the one of the tools in
the total gamut of water resources management.
•In the Indian context it is well established fact that even if we achieve
ultimate irrigation potential we can irrigate only 30% of cultivable land,
remaining 70% is under rain fed conditions where erratic and low rainfall
is the problem.
•Research shows that even the watershed management activities in the
rainfed agriculture may not yield good results if the rainfall deficiency
is more than 20%.
•We are declaring agricultural drought if the rainfall deficiency is 25%
and above.
•If the cloud seeding programme could cover the above deficiency
rainfall it is worth taking.

10. Geographical area of the country :322 M.ha about 60% of
total area
10%-USSR
Cultivable Area : 188 M.ha 29%-U.K.
20% - U.S
Cropped land at present :144 M.ha 26% - Pak.
10% - China
Present area under irrigation : 78 M.ha
Likely irrigated area by the year
2025to meet food production :100 M.ha
Total utilisable Water Resources :114 M.ha.m
Present utilisation : 55 M,ha.m
Water required by the year 2025 : 105 M.ha.m

11. Present population of the country : 1000 million
Population by the year 2025 : 1290 million
Present total food production of the Country : 200 M.tonnes
Required food production by the year 2025 : 350 M.tonnes
Present food consumption per capita per day : 580gms
Average food production at present : 2.2 t/ Ha for
irrigated land and
0.75t/Ha for
un
irrigated land
Average food production required by the
year 2025assuring with more than 70% of
the cropped area will be irrigated : 3 t/Ha

13. Rain Drop
(This is not exact composition of a rain Drop)
Average raindrop size is about 2-3 mm
(Raindrop has a small impurity In the middle)

14. PARTICLE SIZE NATURAL vs FLARE
S.No
HYDERABAD ANANTHAPUR FLARE
Particles Size
(Microns)
% of
Total
Particles Size
(Microns)
% of
Total
Particles Size
(Microns)
% of
Total
1 0.2 41.60% 0.1 41.60% 0.8 28.50%
2 0.4 33.30% 0.3 33.30% 1 12.50%
3 0.6 16.60% 0.5 16.60% 0.2 14.60%
4 0.8 8.30% 0.7 8.30% 0.4 10.20%
• Minimum Diameter of the Rain Drop to fall as rain due to
gravity is 0.5mm
• To form this rain drop and to a bigger size the appropriate
Cloud Condensation Nuclei (CCN) size required is
1-3microns

15. Testing of flare Particles producing Cloud condensation nuclei (CCN), its size distribution
over ground

17. Weather charts used for weather forecast

18. RADAR Image showing seeding of cloud
Flight track
Seeded Cloud
TITAN DISPLAY

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

28. Seeding of Target Cloud 136/147

56. Post seeding Pilot Log

57. Seeding Altitudes over the years 2005-2008.

58. Updrafts observed at the cloud base over the years 2005-2008

60. 25 Aug 09 seeding locations and Post seeding cloud track
First time seeding influence is evaluated by considering zone of influence only under the seeded cloud.

61. 25 Aug 09 seeding locations and Spatial distribution of rain gauge recorded rainfalls (mm)
& Rainfalls below the seeded cloud track.

62. Post seeding rainfall verification over phone with farmers and
administrative peopleDate Name of the Seeding Mandal District Designation Phone Number Status Remarks
6-Nov-09 Owk Kurnool Adarsha Rythu 9440915099 Drizzled at seeded village
6-Nov-09 Peddavadguru Ananthapur M.A.O 9490597714 Rainfall confirmed at seeded village
6-Nov-09 Yellanur Ananthapur M.A.O 9985754095 Rainfall confirmed at seeded village
7-Nov-09 Beluguppa Ananthapur Adarsha Rythu 9177029513 Drizzled at seeded village
7-Nov-09 Kanekal Ananthapur Adarsha Rythu 9951292526 Rainfall confirmed at seeded village
7-Nov-09 Gooty Ananthapur Asst.Geologist A.P Mines 9704197760 Drizzled at seeded village
7-Nov-09 Gummagatta Ananthapur Adarsha Rythu 9492328773 Drizzled at seeded village
7-Nov-09 Peddavadguru Ananthapur M.A.O 9490597714 Drizzled at seeded village
11-Nov-09 Talapula Ananthapur M.A.O 9490597760 Rainfall confirmed at seeded village
11-Nov-09 Simhadripuram Kadapa M.R.O 9959667440 Rainfall confirmed at seeded village
17-Nov-09 Tanakal Ananthapur M.A.O 9490597762 Rainfall confirmed at seeded village
17-Nov-09 Badvel Kadapa M.A.O 9573656243 Drizzled at seeded village
17-Nov-09 Gopavaram Kadapa Adarsha Rythu 9441519891 Drizzled at seeded village
17-Nov-09 Sambepalli Kadapa Adarsha Rythu 9000298920 Rainfall confirmed at seeded village
17-Nov-09 Pendlymarri Kadapa Adarsha Rythu 9959216491 No Rain at seeded village
20-Nov-09 Gorantla Ananthapur M.A.O 9490597748 Rainfall confirmed at seeded village
20-Nov-09 Parigi Ananthapur M.A.O 9490597745 Rainfall confirmed at seeded village
20-Nov-09 Putlur Ananthapur M.A.O 9490597707 Rainfall confirmed at seeded village
20-Nov-09 Kondapuram Kadapa Adarsha Rythu 9440136052 Drizzled at seeded village
20-Nov-09 Simhadripuram Kadapa Adarsha Rythu 9912501709 Drizzled at seeded village
20-Nov-09 Chilamathuru Ananthapur M.A.O 9490597747 Rainfall confirmed at seeded village
21-Nov-09 Obuladivaricheruvu Ananthapur M.A.O 9490597749 No Rain at seeded village
21-Nov-09 Amadgur Ananthapur M.A.O 9490597749 No Rain
21-Nov-09 Ramgiri Ananthapur M.A.O 9490597725 Rainfall confirmed at seeded village
21-Nov-09 Kambadur Ananthapur M.A.O 9490597714 Drizzled at beside seeded village

63. 8day (09 Oct – 16 Oct 2009) Enhanced vegetation Index (EVI) map
8day (12 Dec – 19 Dec 2009) Enhanced vegetation Index (EVI) map
8day Enhanced vegetation Index (EVI) maps derived from MODIS (TERRA/AQUA)

65. TITAN Software
•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.,

66. 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

67. 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.

68. Control Cloud 137
Target Cloud 136/147
Control Cloud 134
Control Cloud 133
Seeding Aircraft

69. Seeding of Target Cloud
136/147

70. Target Cloud
11 Aug 2008 Target & Control Rainfall Analysis
Target cloud track
Control cloud track
Track no.133
Track no.134
Track no.136- 136/147
Distance traveled= 128 Km
Life span= 1.29 Hours
Distance traveled= 82 Km
Life span= 1.07 Hours
Distance traveled= 91 Km
Life span= 2.41 Hours
Seeding Location
18,500ft (500mb) WNW/15 Kt
14,500ft (600mb) WNW/20 Kt
10,000ft (700mb) W/35 Kt
5,000ft (850mb) W/40 Kt
N
Seeding
Altitude (Ft)
Seeding
Altitude (m)
Up Draft in
(Ft/Min)
Up Draft in
(m/s)
Up Draft in
Knots
4500 1350 300 1.5 2.9
Control Clouds
Track no.137

71. Variation of Volume of Seeded and Unseeded clouds on August 11, 2008
0
50
100
150
200
-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60
Time [minutes] *0minutes is the seeding time
Volume[km3
]
SeededVolume UnseededVolume

72. Variation of Area of Seeded and Unseeded clouds on August 11, 2008
0
25
50
75
-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60
Time [minutes] *0minutes is the seeding time
Area[km2] Seeded Area Unseeded Area

73. Variation of Mass of Seeded and Unseeded clouds on August 11, 2008
0
25
50
75
-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60
Time [minutes] *0minutes is the seeding time
Mass[k.tons]
Seeded Mass Unseeded Mass

74. Variation of VIL of Seeded and Unseeded clouds on August 11, 2008
0
1
2
3
4
-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60
Time [minutes] *0minutes is the seeding time
V.I.L.[kg/m2] Seeded VIL Unseeded VIL

75. DOUBLE RATIO METHOD
•It is the ratio of two ratios
•The numerator is the ratio of total rainfall of Target
area [S] to the total rainfall of Control area [NS] during
seeding days [ S/NS]
•The denominator is the ratio of total rainfall of the
Target area [H] to the total rainfall of Control area [K]
during 10 unseeded years. [H/K]
•Reference: Dr.Ali Umran Komuscu, Turkey, Journal of
Weather Modification, Volume 40,April 2008, Page No. 17-
27.

76. Where
• IC = Impact Coefficient
• S = Total rainfall in the target area during seeding period
• NS = Total rainfall in the control area during seeding period
• H = Total rainfall in the targeted area during 10unseeded years
• K= Total rainfall in the control area during 10unseeded years
• [ I.C >1 indicates influence of seeding ]
]/[
]/[
.
KH
NSS
CI =

77. Correlation between Rain fall of Target and Rain fall of
Control stations during 10 unseeded years
(1990-2000)
Target/Control Anantapur Target/ Control Mahaboobnagar
Kadapa 0.67 Medak 0.54
Chittoor 0.69 Nalgonda 0.78
Kurnool 0.88 Kurnool 0.72
Target/Control Nalgonda Target/Control Ranga Reddy
Medak 0.45 Medak 0.78
Ranga Reddy 0.6 Mahaboobnagar 0.83
Mahaboobnagar 0.78 Nalgonda 0.6

78. NALGONDA vs. CONTROL stations Comparison
Correlations coefficients
Target /Control stations Mahaboobnagar Ranga Reddy Medak
Nalgonda 0.78 0.6 0.45
Impact Coefficients 2009 for 15 Days of Cloud Seeding operations
a = S/NS b = H/K I.C= a/ b Change %
Nalgonda vs. Mahaboobnagar 0.72 1.07 0.67 No Change
Nalgonda vs. RangaReddy 1.37 0.85 1.61 61
Nalgonda vs. Medak 1.13 0.83 1.83 36
Impact Coefficients 2008 for 17 Days of Cloud Seeding operations
a = S/NS b = H/K I.C= a/ b Change %
Nalgonda vs. Mahaboobnagar 1.68 1.07 1.57 57
Nalgonda vs. RangaReddy 1.61 0.85 1.89 89
Nalgonda vs. Medak 1.52 0.83 1.83 83
Impact Coefficients 2007 for 21 Days of Cloud Seeding operations
a = H/K b= S/NS I.C= b/a Change %
Nalgonda vs. Mahaboobnagar 1.41 1.07 1.32 32
Nalgonda vs. RangaReddy 1.18 0.85 1.39 39
Nalgonda vs. Medak 1.84 0.83 2.22 122

81. Rain M ass of 30 Seed ed and 30 Un see ded clou ds -Hyd erab ad 08
0
100
200
300
400
500
600
700
5 10 15 20 25 30 35 40 45 50 55 60 65
Time [minutes]
RainMass[ktons]
Seeded RM Hyd 08
Unseeded Rm Hyd 08
Rain Mass of 27 Seeded and 30 Unseeded clouds -Anantapur 08
0
100
200
300
400
500
600
700
800
5 10 15 20 25 30 35 40 45 50 55 60 65
Time [minutes]
RainMass[ktons]
See ded RM AT P 08
Uns eed ed RM ATP 08
Temporal Variation of Rain Mass with different data sets

83. Weekly CUMULATIVE RAINFALL STATUS for the year-2009
Week EXCESS NORMAL DEFICIENT SCANTY No Rain TOTAL MANDALS
ANDHRA RSAD % in RSAD ANDHRA RSAD % in RSAD ANDHRA RSAD % in RSAD ANDHRA RSAD % in RSAD ANDHRA RSAD % in RSAD ANDHRA RSAD
01 JUN-10 JUN 2009 195 132 67.69 124 72 58.06 217 115 53.00 326 180 55.21 242 154 63.64 1104 653
01 JUN-17 JUN 2009 153 146 95.42 163 121 74.23 263 176 66.92 466 188 40.34 59 22 37.29 1104 653
01 JUN-24 JUN 2009 157 152 96.82 161 136 84.47 294 180 61.22 461 173 37.53 31 12 38.71 1104 653
01 JUN-01 JUL 2009 159 128 80.50 197 129 65.48 374 222 59.36 363 168 46.28 11 6 54.55 1104 653
01 JUN-08 JUL 2009 108 75 69.44 212 115 54.25 504 283 56.15 278 178 64.03 2 2 100.00 1104 653
01 JUN-15 JUL 2009 87 36 41.38 219 107 48.86 537 318 59.22 261 190 72.80 0 2 0.00 1104 653
01 JUN-22 JUL 2009 51 14 27.45 187 86 45.99 568 308 54.23 298 245 82.21 0 0 0.00 1104 653
01 JUN-29 JUL 2009 27 13 48.15 118 44 37.29 536 280 52.24 423 316 74.70 0 0 0.00 1104 653
01 JUN-05 AUG 2009 22 5 22.73 111 37 33.33 494 265 53.64 477 346 72.54 0 0 0.00 1104 653
01 JUN-12 AUG 2009 17 3 17.65 79 20 25.32 459 251 54.68 549 379 69.03 0 0 0.00 1104 653
01 JUN-19 AUG 2009 21 12 57.14 132 70 53.03 556 349 62.77 395 222 56.20 0 0 0.00 1104 653
01 JUN-26 AUG 2009 42 31 73.81 207 140 67.63 670 381 56.87 185 101 54.59 0 0 0.00 1104 653
01 JUN-02 SEP 2009 80 68 85.00 291 215 73.88 662 332 50.15 71 38 53.52 0 0 0.00 1104 653
01 JUN-09 SEP 2009 56 51 91.07 310 222 71.61 673 340 50.52 65 40 61.54 0 0 0.00 1104 653
01 JUN-16 SEP 2009 66 58 87.88 303 223 73.60 667 332 49.78 68 40 58.82 0 0 0.00 1104 653
01 JUN-23 SEP 2009 60 58 96.67 283 207 73.14 688 341 49.56 73 47 64.38 0 0 0.00 1104 653
01 JUN-30 SEP 2009 92 86 93.48 345 254 73.62 621 285 45.89 46 28 60.87 0 0 0.00 1104 653
01 Jun- 07 Oct 2009 122 115 94.26 346 233 67.34 614 286 46.58 22 19 86.36 0 0 0.00 1104 653
01 Jun- 14 Oct 2009 107 104 97.20 305 211 69.18 672 321 47.77 20 17 85.00 0 0 0.00 1104 653
01 Jun- 21 Oct 2009 96 95 98.96 273 193 70.70 696 339 48.71 39 26 66.67 0 0 0.00 1104 653
01 Jun- 28 Oct 2009 90 89 98.89 253 178 70.36 709 357 50.35 52 29 55.77 0 0 0.00 1104 653
01 Jun- 04 Nov 2009 83 82 98.80 236 165 69.92 717 358 49.93 68 48 70.59 0 0 0.00 1104 653
01 Jun- 11 Nov 2009 96 95 98.96 298 228 76.51 676 312 46.15 34 18 52.94 0 0 0.00 1104 653
01 Jun- 18 Nov 2009 86 85 98.84 321 242 75.39 672 310 46.13 25 16 64.00 0 0 0.00 1104 653
01 Jun – 25 Nov 2009 92 88 95.65 352 259 73.58 647 298 46.06 13 8 61.54 0 0 0.00 1104 653
Pre and Post seeding weeks

84. 20 Jul – 23 Nov 2009
Total No.of seedings = 541 01Jun – 23 Nov 2009
Seeding Locations Rainfall Status
Upto Seeding Period

85. 23 Jul – 23 Sep 2009
Total No.of seedings = 339
01Jun – 23 Sep 2009
Seeding Locations Rainfall Status
Before October Flood

86. NO.OF EXCESS MANDALS=808
NO.OF NORMAL MANDALS =265
NO.OF DEFICIENT MANDALS =32
NO.OF SCANTY MANDALS =00
No.of No Rain Mandals =00
NO.OF EXCESS MANDALS= 173
NO.OF NORMAL MANDALS = 589
NO.OF DEFICIENT MANDALS =335
NO.OF SCANTY MANDALS = 08
No.of No Rain Mandals = 0
Spatial distribution of Seasonal Rainfall in the
Years 2010 and 2011 (as on 15th
Sep)
2010
2011

87. 0
100
200
300
400
500
600
700
800
1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010
Average annual
monsoon rainfall
3 yrs. Moving Average
annual monsoon rainfall
0
100
200
300
400
500
600
700
800
900
1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010
Average annual
monsoon rainfall
3 yrs. Moving Average
annual monsoon rainfall
Nalgonda seeded
Nalgonda unseeded
Long term rainfall analysis during monsoon between seeded and
unseeded areas in the Nalgonda district, A.P
year
Rainfall
year
Rainfall

88. Appearance of Seedable Clouds [>30min] over Hyderabad RADAR
from 20th July to 07 August, during the years 2007,2008 & 2009
189
120
62
0
20
40
60
80
100
120
140
160
180
200
TOTAL
NoofClouds
2007Year 2008 Year 2009 Year

89. S.No Year No of
Aircrafts
used
No of
RADARs
Used
Total
districts
covered
No of
Mandals
seeded
% of
Rainfall
attributed
to cloud
seeding
operations
No. of
water samples
analyzed
Cost
In Crores
1 2003 1 0 1 63 -- -- --
2 2004 3 2 16 510 -- 14 10.67
3 2005 3 2 10 476 12.85 108 20.63
4 2006 2 2 10 552 17.25 610 14.24
5 2007 2 2 12 566 19.17 2159 22.37
6 2008 2 2 12 651 18.25 942 24.9
7 2009 3 2 12 558 17.01 536 25.40
Summary of cloud seeding operations over Andhra Pradesh
(2004 – 2009)
•Cloud seeding water cast = 3 paise per Cu.m

90. • Warm cloud seeding is more effective in the last four years
• Cloud Seeding is effective on Continental clouds over Anathapur,
Cuddapah, Kurnool, Mahbubnagar, Nalgonda and Ranga Reddy districts
where seeding particle size suits for the enhancement of Clouds after
seeding.
• Cloud Seeding is ineffective on maritime clouds over coastal districts of
Guntur, Prakasam, Nellore and eastern half of Chittore.
• Probably the size of seeded particle is smaller than Salt particles found
in this atmosphere. Hence instead of forming into a rain drop, more
droplets have formed and dissipated. Therefore different increased size
CCN is required for maritime clouds.
• It is also observed in general that cloud seeding is more effective if we get
bigger size monsoon clouds and it is less effective if we get smaller size
monsoon clouds.
• Of late 0.5kg flares with 3 to 4 micron size is observed to be yielding
good results.
Lessons learnt:

91. Thank you……….