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Making weather ­-- How can one artificially turn

Making weather ­-- How can one artificially turn a cloud into rain (hail), and how can one make it disappear?. by Doreen Wachner. outline:. historical developments of the artificial weather important kind of weather influencing hail-suppression effects of the artificial weather.

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Making weather ­-- How can one artificially turn

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  1. Making weather ­-- How can one artificially turn a cloud into rain (hail), and how can one make it disappear? by Doreen Wachner

  2. outline: • historical developments of the artificial weather • important kind of weather influencing • hail-suppression • effects of the artificial weather

  3. historical developments of the artificial weather >>> basis of the experiments of weather-influencing is the basis-research of cloud-physics 1. step: ( 1911 – 1945 ) - theories of precipitation formation 2. step: ( 1946 – 1947 ) - discovery of chemicals to dissolve the ice-formation 4 steps of development 3. step: ( 1947 – 1954 ) - some experiments of weather-influencing 4. step: ( 1955 to now ) - economic applicability .

  4. important kind of weather-influencing creation of artificial rain influencing / dissolution of fog hail-suppression .

  5. hail-suppression hail-damage: 14,5 million €/a hail-damage in Steiermark 300 million $/a harvest-damage and 25 million $/a damage to property in USA example for Germany: 1984 in München

  6. hail-risk in Germany green: low hail-risk red: heavy hail-risk Quelle: Risikostatistik Hagel 1980-1998

  7. microphysical processes: microphysics of rain drops microphysics of ice particles .

  8. microphysics of ice particles

  9. microphysics of ice particles three kinds of ice particle formation 1) deposition 2) freezing nucleation 3) contact nucleation

  10. formation of hail basis of the formation of hail: 1) existence of ice particles ( freezing nuclear ) 2) existence of undercooled water ( T< 0°C ) .

  11. formation of hail: " two-stage process of the hail-formation " - first-stage: ________ a new cloud area forms these particles acts as nuclear of the growth of hail - second-stage: ___________ the nuclear with undercooled water drops grow to hailstone >>> conditions of the two-stage process are dynamical operations in the clouds !!!

  12. Which “cloud-kind” will be seeded ? seeding hypotheses “single cell thunderstorm” “more cell thunderstorm” “super cell thunderstorm”

  13. picture: “single cell thunderstorm”

  14. picture: “more cell thunderstorm”

  15. picture: “super cell thunderstorm”

  16. methods of hail-suppressions 1) competition principle 2) cloud seeding with airplane 3) conception of the accelerate growth of drops in the principal prevailing of wind 4) conception of the path reduction of hail grains 5) ice formation hypothesis 6) conception of early precipitate of hail-embryos 7) conception of artificial influencing of cloud dynamics .

  17. important seed substance is silver iodide ! 1947 >>> first step of the scientific weather influencing (B. Vonnegut) chemical properties of AgI : three modifications  - AgI (cubic room-centers )  - AgI (cubic “zinkblende”)  - AgI (hexagonal “wurtzit-grating” ) .

  18. chemical properties of AgI : -4,5°C ( -5,2°C completed) >>> AgI – efficiency affinity to hexagonal snow crystals no toxicity AgI disintegrates photochemically to silver and iodine (UV-light)

  19. effect of AgI to clouds AgI >>> freezing nucleus use of -AgI combination of seed substance: >>> four parts of AgI and one part of NaI nuclear action of AgI based of: >>> heterogeneous ice nucleation ( homogeneous ice nucleation : < -40°C ) >>> hexagonal structure favors the nuclear action of AgI .

  20. distribution of AgI in the clouds effect of AgI starts at -7°C AgI distribution in the cloud = principle of the Gauss-distribution: >>> AgI amount: 8 g >>> AgI density of all particles in the cloud: 10-15 g/cm3 .

  21. distribution of AgI in the clouds consequence is that: ice nucleus number ( activation temperature: -7°C ) = 1013 ice nucleuses/ kg AgI ice nucleus concentration ( -7°C) = 10-2 l-1 >>> -10°C = 10 l-1 >>> -20°C = 100 – 1000 l-1 AgI-seeding ( temperature: -20°C ) produces 100 more ice nucleus per liter in the cloud as in a natural cloud ! ! !

  22. number of ice nucleus depending on the temperature AgI AgI – NaI Lösung

  23. combination and amount of AgI seed substance ( >>> values from the “Steierischen Hagelabwehrgenossenschaft” 1991 - 2002 ) solution combination: 1 liter acetone ~ 1000g four parts AgI ( 62,5 g ) one part NaI ( solvent ) flow volume: 5 – 6 l/h to released AgI amount: 300 – 400 g/h per generator .

  24. used airplane and generator ( burner ) to AgI seeding

  25. used airplane and generator ( burner ) to AgI seeding

  26. conditions of the AgI-seeding: 1) enough “artificial nucleuses” to yield in the cloud 2) these nucleuses must not be too long and must not stay too high in the updraft

  27. number of hits to seeding per airplane “single cell thunderstorm”: >>> number of hits at seeding = 90 – 100 % “super cell thunderstorm”: >>> number of hits at seeding = 50 % “more cell thunderstorm”: >>> number of hits at seeding = between single- and super cell thunderstorm

  28. number of hits to seeding per airplane: very important is the time component time of development (exist) of the hail clouds: “single cell thunderstorm”: 10 – 15 min. “more cell thunderstorm”: 20 – 90 min. “super cell thunderstorm”: >30 min. general: 80 % of the clouds will be real seeding

  29. new developments in the cloud seeding research more application of sodium chloride new seeding substance: >>> complex of AgClI*0,5 NaCl aim of the new seeding substances is: >>> improvement of the rain dissolution >>> improvement of the hail suppression

  30. effects of the artificial weather flood disaster from Lynmounth ( 1952 ) weather influencing in Vietnam-war prohibition through UNO convention artificial rain prevented aridity in Chonburi .

  31. literature: [1] E. Heyer, Witterung und Klima – Eine allgemeine Klimatologie, B.G. Teubner Verlagsgesellschaft, 9. Aufl., Leipzig, 1993. [2] W. Atkinson, Wetterforschung – Analyse, Vorhersagen und Beeinflussung des Wetter, Deutsche Verlags-Anstalt Stuttgart, 1.Aufl., Stuttgart, 1970. [3] P.D. Jones, History and Climate – Memories of the Future?, Kluwer Academic/Plenum Plublisher, 1.Aufl.,New York, 2001. [4] J. Bendix, Geländeklimatologie, Gebrüder Borntraeger Verlagsbuchhandlung, 1. Aufl., Stuttgart, 2004. [5] http://www.klimaforschung.net/silberjodid/index.htm

  32. literature: [6] http://www.wetter-zentrale.de/cgi-bin/wetterchronik/home.pl [7] http://www.hagelabwehr.at/brenner.asp [8] http://www.bayercropscience.de/ [9] http://www.chinadaily.com.cn/english/doc/2004-07/13/content_348065.htm [10] http://www.sonnenseite.com/fp/archiv/Art-Zukunft/regenmacher.php [11] www.guardian.co.uk/china/story/0,7369,1261697,00.html

  33. Thank you

  34. principle of the Gauss-distribution

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