Cloud seeding the way out!

During Sri Lanka’s inter-monsoonal period many individuals believe they can predict rain by ‘feel’. On the west coast, the high humidity that induces profuse perspiration in mid-morning is a sure indication of precipitation in the evening. Unfortunately, despite the symptoms rain isn’t forthcoming.

An observer looking eastward (inland) from the west, sees fair weather cumulus clouds that are too small to produce rain. The problem is caused by high humidity in the atmosphere, yet not enough nuclei of small particles of dust or smoke for rain drops to condense around. When water condenses from vapour to liquid there is release of latent heat, making the cloud warmer than the surrounding atmosphere. That causes the cloud to rise, developing vertically to a height of 50,000 feet on occasion, resulting in so-called ‘towering’ cumulus clouds that produce heavy rain.

When this does not occur, the solution is to artificially add, or ‘seed’, small particles of dry ice, salt and silver iodide into the atmosphere. This could be done by exploding skyrockets (fireworks!), or by seeding the clouds using light aircraft.

Since 1983 in Tamil Nadu, India has been deploying a fleet of light aircraft dedicated to cloud-seeding activities, and experimentation on more effective aerial methods of producing artificial rain.

Beechcraft (Raytheon) Super King Air 200 airplane (left) used by India for cloud-seeding and research. Photo courtesy the Indian Institute of Tropical Meteorology (IITM).

Yet the Sri Lankan Department of Meteorology is seemingly inactive in that field of endeavour. The Sri Lanka Air Force (SLAF) has similar aircraft to those used in India to create ‘rain on demand’. Why couldn’t the government have one or more of those airplanes adapted to serve the nation during adverse, drought-stricken times? Alternatively, if assistance is sought from India, data and research findings could be exchanged between our country and its near-neighbour.

Sure, times are hard and it is going to be expensive. But if the President cuts down on his international travel and sends his diplomats instead, Sri Lanka could find all the money it requires for cloud seeding. The rain produced will cool down a part of the Island. It will also clear the pollution that is created over Sri Lanka by India. Or, do we just grin and bear the heat?

Guwan Seeya