The Experiment of Ice Nucleus Generating Efficiency by Model 37 Silver Iodide Shell

Dang Juan; Su Zhengjun; Fang Wen; Fang Chungang

doi:10.11898/1001-7313.20160202

Vol.27, NO.2, 2016

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Article Navigation > Journal of Applied Meteorological Science > 2016 > 27(2): 140-147

Dang Juan, Su Zhengjun, Fang Wen, et al. The experiment of ice nucleus generating efficiency by model 37 silver iodide shell. J Appl Meteor Sci, 2016, 27(2): 140-147. DOI: 10.11898/1001-7313.20160202.

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Dang Juan, Su Zhengjun, Fang Wen, et al. The experiment of ice nucleus generating efficiency by model 37 silver iodide shell. J Appl Meteor Sci, 2016, 27(2): 140-147. DOI: 10.11898/1001-7313.20160202.

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The Experiment of Ice Nucleus Generating Efficiency by Model 37 Silver Iodide Shell

DOI: 10.11898/1001-7313.20160202

Dang Juan^{1,2
,
,},
Su Zhengjun^1,2,
Fang Wen^1,2,
Fang Chungang^1,2

1.
State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081
2.
Weather Modification Center of CMA, Chinese Academy of Meteorological Sciences, Beijing 100081

Received Date: 2015-07-06
Rev Recd Date: 2015-09-17
Publish Date: 2016-03-31

Abstract

Abstract

Model 37 shell is one of the main carrier of silver iodide catalytic agent usedin rainfall enhancement and hail suppression operations. Nucleating effectiveness values of silver iodide filled in shell are important reference to measure the amount of silver iodide catalytic agent using in weather modification operation. Using a 1200 L isothermal cloud chamber and a 20 m³steel plate explosion chamber, the first uniform test of ice nucleus generating efficiency of model 37 silver iodide shells isimplemented by Weather Modification Center of CMA (WMC) from November to December of 2013, and samples chosen randomly from 2 manufacture factories is examined. Uucleation rates of two kinds of sample are detected at eight temperature between-3℃ to-20℃. Results show that fitting values of nucleating effectiveness of two kinds of samples are all in the range of 10⁹-10¹²/(g·AgI) with the temperature from-6 ℃ to-20℃, and the threshold temperature is-4℃. The nucleating effectiveness of sample 2 is higher than that of sample 1 obviously, and the maximum difference of fitting values between them is 8.4 times at-14℃. The comparison between this experiment and past results given by domestic different experiments is carried out. Results indicate the nucleation rates of sample 1 and sample 2 are higher than the past results at-14℃ above, and they are both 2 to 3 orders of magnitude more effective than the detection values of past experiments at-10℃. To seek cause for this significant difference, a detailed comparative analysis onexperiment condition is carried out. Some techniques applied to the 1200 L isothermal cloud chamber such as temperature controlling, fog making and ice crystals counting are improved, and impacts of those operations are reduced. Meanwhile, larger volume of cloud chamber results in less border effect, and longer time of holding fog in cloud chamber, so it simulates actual atmospheric condition better. Based on above discussions, the testing results of model 37 silver iodide shell nucleation rate are reliable. Furthermore, in view of the great deviation in different experiments, it is very necessary to uniformly test nucleation rate of seeding agent on the same experiment platform.
- isothermal cloud chamber;
- nucleation rate;
- silver iodide;
- model 37 shell

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References(24)

Figures and Tables

Fig. 1 The external view of 1200 L isothermal cloud chamber

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Fig. 2 The temperature gradient of the horizontal direction (a) and the vertical direction (b) in the cloud chamber

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Fig. 3 The nucleating effectiveness of sample 1 and sample 2

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Fig. 4 The comparison between the sample 2 and the same model shell tested in 2002

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Fig. 5 The comparison between sample 1, sample 2 and past results given by different experiments

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Table 1 The comparison of fitting values of nucleating effectiveness between sample 1 and sample 2(unit:1/(g·AgI))

温度/℃	样品1	样品2
-6	7.4×10⁹	7.4×10⁹
-8	2.0×10¹⁰	5.3×10¹⁰
-10	5.3×10¹⁰	2.7×10¹¹
-12	1.3×10¹¹	9.9×10¹¹
-14	3.1×10¹¹	2.6×10¹²
-16	6.8×10¹¹	4.8×10¹²
-18	1.4×10¹²	6.5×10¹²
-20	2.8×10¹²	6.2×10¹²

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Table 2 The detail information of all samples tested in each experiment

样品编号	样品名称	检测年份	炮弹中碘化银含量/g
1	1973-6g	1973	6
2	1973-4g	1973	4
3	1980-4g	1980	4
4	1980-1g	1980	1
5	1985-4g	1985	4
6	1985-1g	1985	1
7	2002-1g	2002	1
8	样品1	2013	1
9	样品2	2013	1

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Table 3 The comparison among operating conditions of different experiments

检测时间	爆炸室	样气稀释	云室	通雾方式	冰晶计数方法	样品名称
1973年 (成核率检定小组^[13])	铁塔结构式 12 m³	是	2 L混合云室	电炉加热水形成水蒸汽直接通入云室	糖盘法	1973-6g, 1973-4g
1980年 (石安英等^[15])	石头、水泥结构式114 m³	是	3.25 L混合云室	水蒸汽直接通入云室	糖盘法	1980-4g, 1980-1g
1985年 (陈汝珍等^[16])	水泥洞式 375 m³	是	9.3 L混合云室	由雾化器产生常温雾直接通入云室	糖盘法	1985-4g, 1985-1g
2002年 (杨绍忠等^[17])	地下水泥式 24 m³	是	20 L混合云室	由雾化器产生常温雾直接通入云室	玻片法	2002-1g
2013年 (人影中心检测组)	地下钢板式 20 m³	否	1200 L等温云室	由雾化器产生常温雾经预冷后通入云室	玻片法	样品1, 样品2

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