Operation to induce rainfall provides break from heat and haze in Selangor

PETALING JAYA: The Meteorological Department’s cloud seeding operation over Selangor brought a brief break from the stifling heat and choking haze.

The department’s national weather centre director Muhammad Helmi Abdullah said yesterday’s operation was to induce rainfall over dams and water catchment areas.

He said cloud seeding had also been planned over parts of Malacca, Negeri Sembilan and Johor but there were not enough clouds there.

“We target rain clouds over or near dams and water catchment areas,” he told The Star.

“Even if the clouds are not directly above the areas, we expect the winds to carry them towards these places.”

Muhammad Helmi said the evening operation was a success because it brought about rainfall in several areas but until late yesterday it was not known if the rain was enough to raise water levels at the dams.

Muhammad Helmi said the operation was led by the department’s atmospheric science and cloud seeding division, using a Royal Malaysian Air Force (RMAF) aircraft carrying four 1,000-litre tanks of water containing 150kg of salt each.

He said the division identified suitable conditions for cloud seeding, based on Sunday’s weather forecast and alerted RMAF to be on standby.

Another round of cloud seeding would be done today provided weather conditions were suitable.

Explaining the process, he said, cloud seeding was a method of inducing rain, and not making rain.

“Salt solution is sprayed at the base of the identified clouds. The particles will be carried upwards by thermals or upward currents of warm air.

“This will form water vapour that will grow in size as it moves upwards until they grow heavy and fall down as rain.

“Through cloud seeding, we are actually accelerating the process of rainfall production as well as increasing the amount of rainfall.

“It takes between 15 minutes to half an hour for rain to fall after the solution has been sprayed,” he added.

Muhammad Helmi said there was a “very narrow window of opportunity” over the past week as the weather conditions kept fluctuating.

He said the winds were also stronger, resulting in low chances of rain clouds being formed.

In SEREMBAN, a downpour in several areas in the state over the weekend brought some relief but did little to replenish supply in the four major dams.

Checks with Syarikat Air Negri Sembilan showed that levels at the Sg Terip, Kelinchi, Talang and Gemencheh dams remained at near critical levels.

The level at the Sg Terip dam, which supplies treated water to households here, was at 100.12m, about six metres above the 94.6m critical mark.

As for the Kelinchi dam, it was at 199.1m (critical level 198.3m) while Talang was at 148.45m (140.5m) and Gemencheh at 99.66m (98m).

All households in the state, however, have continued to receive supply.