Enhancing rainfall by cloud seeding.
When the State of Israel was still in its infancy, Israeli leaders realized that the country’s climate requires creative, innovative and advanced solutions for the water industry. Consequently, cloud seeding technology was brought over to Israel in 1961, and EMS – Electrical Mechanical Services, then Mekorot’s technical department, was put in charge of its implementation.
EMS has been engaged in the field of rainfall enhancement for five decades. The Company plays an active part in both the scientific and research aspects, implemented jointly withwith leading research and academic organizations. Practical research is conducted through seeding flights, operating furnaces, cloud RADAR, satellite photographs and other advanced technologies.
How is Cloud Seeding Conducted?
Small drops of rain form at the bottom of every cloud. These drops are not heavy enough to fall as rain. Nature’s rainfall process begins when the ice crystals that form in the cloud proliferate at a higher rate than that of the drops of water, and form frozen nuclei around which the water collects until they fall to earth as rain, due to their weight.
The seeding is carried out by means of a material know as Silver Iodide (AgI), which accelerates the creation of ice particles in the cloud. Silver Iodide is dispersed into the atmosphere by aircraft flying at an altitude of 5,000 feet above the cloud base or by means of furnaces on the ground. Because clouds are created by vertical up-flowing currents, the Silver Iodide particles rise into the atmosphere from the furnaces and when they reach a temperature of – 40° C, they begin forming ice particles that accelerate the rain making process.
In order to time the seeding activities, we use RADAR and satellite data as well as meteorological observations, provided by various organizations, including the Israeli Meteorological Services, and the Civil Aviation Authority.
EMS operates research aircraft, equipped with measuring and recording device systems, for the benefit of experimentation. These systems document the changes that take place as a result of the impact of Silver Iodide seeding in the atmosphere.
Thanks to the many experiments and the ongoing research, EMS is able to streamline its activities in the field of rainfall enhancement, through technological advancement and improving work methods. The research also helps position the Company as an international knowledge center, which has led the Company to be selected to carry out a similar project in Italy and to consult on similar projects in other countries.
About Aircraft and Furnaces
Cloud seeding in Israel is implemented by means of aircraft and ground based furnaces. The aircraft fly along predetermined flight paths, at an altitude of 5,000 ft. above the cloud base, and dispense a mixture of Silver Iodide and acetone into the clouds that cross their paths.
The furnaces, positioned in fixed locations near mountaintops, also dispense the mixture that rises through hot air currents to the clouds above.