Artificial Rain

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Analytical Chemistry Department Faculty Of Pharmacy Cairo University Presents

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Artificial Rain

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By: Mennatullah Magdy Fahmy 2 nd year Faculty Of Pharmacy Cairo University Cairo , Egypt

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How is rain formed in nature?? wind passing over the seas collects water vapour converting them to tiny droplets , going high in the sky , these droplets come together forming big ones ( the process is called nucleation) which attract more droplets so becomes bulky , and rainfall occurs .

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Artificial rain or cloud seeding is a process of weather modification depending on scientific technology that can improve cloud precipitation ( rainfall ) that aims to increase water availability worldwide . What’s artificial rain??

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Warm cloud seeding (Hygroscopic seeding ) Is done using salts such as NaCl , CaCl 2 at temperatures not colder than 0 0 C producing rain .

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2. Cold cloud seeding ( Glaciogenic seeding ) By using supercooling agents such as AgI , Dry ice at temperatures colder than 0 0 C which act as ice nuclei , thus producing larger snow crystals. .

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Methods of cloud seeding Method 1 : spraying clouds with substances like Silver Iodide (costly) , solid carbon dioxide (dry ice) or powdered Sodium Chloride

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An airplane spraying the nucleating agents into the clouds

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Method 2 : It involves three stages 1 st Stage Agitation Involves stimulation of air masses condense and come together using calcium chloride, calcium carbide or calcium oxide .

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Where clouds are built up using Urea , Kitchen salt or ammonium nitrate . 2nd Stage Building-up stage

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3 rd Stage Seeding Where bombardment by nucleating agents occurs thus formation of water droplets and raining occurs .

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Why do we need artificial rain??

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Creating new sources of water in order to face the world's demands and the problem of lack of water resources . Helping the zones suffering drought . Facilitating agriculture due to the presence of rain . Advantages of artificial rain

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Countries using artificial rain technology At present ,China has the largest cloud seeding system in the world . Thailand . Mumbai , the Indian capital . Dubai , in U.A.E .

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Artificial rain in Dubai 2008

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Drawbacks of artificial rain It was found that the use of chemicals such as AgI has some bad consequences on the long term as it has hazardous effects on humans , animals it may also cause soil pollution.