SINGAPORE - Residents in the west of Singapore scurried for cover on Tuesday as a rare hailstorm uprooted trees and disrupted traffic.
The phenomenon - which was last reported here in 2008 - may or may not be linked to haze, said the National Environment Agency (NEA) and weather experts.
But it is unlikely to have been triggered by cloud seeding in Indonesia to extinguish fires in Riau, they said, as the seeding took place hundreds of kilometres away, and hail is a local phenomenon.
"Hail is produced by sizeable cumulonimbus clouds located in very high altitude where temperature is very low," said atmosphere scientist Erwin Mulyana of Indonesia's Agency for the Assessment and Application of Technology.
"Above Riau, the cumulonimbus clouds are thin and small, and are not at a high altitude."
Both the NEA and external experts did not rule out the possibility that fine haze particles in the air had helped to produce hail.