More than 30 flights a day have been heading for the clouds in Thailand to persuade them to part with their water. The planes spray silver iodine, salt and dry ice causing vapour droplets to freeze and fall to the ground. Cloud seeding, as this technique is known, 1,000 times in less than a month has eased the toughest drought for seven years by 80 per cent.

The planes use a technique patented by the King Bhumibol Adulyadej of Thailand, spraying chemicals into warm and cold clouds at different altitudes to make rain fall over a wide area.

Thailand's success has led countries including Cambodia and Oman to ask for technical assistance. However, Thailand says that cloud seeding only works if you have the right type of clouds and where humidity is higher than 60 per cent.

Cloud seeding experiments have been taking place for more than 60 years and the technique has also been applied successfully in Australia, China, Malaysia and the Philippines.

Related News: Cloud seeding: taking off in West Africa, Source, 16 Jun 2004; Oman plans to try cloud seeding, Source, 9 Aug 2004

Source: Independent on Line, 16 Apr 2005

Tags: water collection, water supply