It's raining, it's pouring ... cloud seeding does its part

PETALING JAYA: Klang Valley residents heaved a sigh of relief Monday evening. The Meteorological Department confirmed that the rain which fell over several areas in Selangor was due in part to a successful cloud seeding operation.

Its national weather centre director Muhammad Helmi Abdullah said the operation was a success in Selangor.

“We had already foreseen that Selangor is a good candidate for the operation,” he told The Star.

Muhammad Helmi said the Selangor operation was led by the department’s atmospheric science and cloud seeding division, with a TUDM aircraft used to transport four 1,000-litre tanks of water containing 150kg of salt each.

Although the department planned to carry out the operation in Negri Sembilan, Malacca and Johor as well, he said it had to be cancelled at the last minute due to the lack of suitable clouds.

Muhammad Helmi explained that cloud seeding was a process of inducing rain, not making rain, as the formation of moisture-laden towering cumulus clouds meant that rain would happen eventually. 

He said optimal conditions for cloud seeding included the need for light and variable winds, which were conducive for the formation of such rain clouds.

“In the past week, weather conditions kept fluctuating and there was a very narrow window of opportunity. The winds were also stronger last week, meaning a low chance of rain clouds forming,” he explained.

He said that the salt solution was sprayed at the base of the identified clouds, adding that the salt particles would be carried upwards by thermals, which are upward currents of warm air.

He said this would form water vapour that would grow in size as they moved upwards, until they grew so heavy that they would then fall down as rain.

“Through cloud seeding, we are actually accelerating the process of rainfall production as well as increasing the amount of rainfall. We estimate it will take 15 minutes to half an hour for rain to fall after the solution is sprayed,” he said.

Muhammad Helmi expressed confidence that the rain would fall in the targeted areas, but said he was unable to predict how much it would increase water levels in the dams as the amount of rainfall depended on factors influencing each individual cloud.