Experiment under way to induce rain

The project called Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) is a national programme launched by the Central Government. It involves injecting small quantities of specific substances (like aerosols),naturally found in clouds,causing them to open up.

Scientist Dr J R Kulkarni,programme manager of CAIPEEX,who heads the project explained,“Rain usually falls when large water drops in a loaded cloud collide with each other and become large enough to fall down. Sometimes,mainly when the weather is not cool enough,the water vapours keep floating in the form of smaller droplets. To fall they need to get together and form large drops. Aerosols and some other salts facilitate cloud composition.”

CAIPEEX will be carried out in three phases. Phase I,which is presently under way,involves intensive cloud and aerosol observations over different parts of India during May-September 2009. In Phase II,‘precipitation enhancement’ experiments would be carried out by artificially seeding the clouds in 2010 and 2011. The analysis of the data will then be carried out in the presence of hails or ice slabs in the clouds which can damage aircraft.

“There have been other experiments of cloud seeding in the 1970s . In fact experiments were carried over Mumbai in the monsoon seasons in 1973 and 1974. However,this is the first country-wide experiment on this scale. If it works,the economy can be revived,” Kulkarni explained. Experts from the India Meteorology Department,IIT Bombay,and Tata Institute of Fundamental Research (TIFR),Mumbai,have contributed to the experiment.