Singapore is suffering its worst haze in history. Singapore's main index for air pollution hit a measurement of 401 at midday Friday, exceeding previous highs of 371 on Thursday and 321 on Wednesday, both of which were record readings.
A severe hail storm along with damaging winds and heavy rain was seen across Singapore Tuesday afternoon. This is an extremely rare event for the island nation that only lies two degrees from the equator and never experiences temperatures below the freezing mark through a good portion of the lower atmosphere. Therefore hail of any size is a extremely rare event. The last time it hailed in Singapore was 27 March 2008.
So what caused the hail and was it related to the unprecedented levels of smoke and haze in Singapore? Research documented in the Journal Science edition Febuary 2004 indicates that that may be the case.
The report indicates that air pollution and smoke may suppress rainfall initially. But the remaining moisture in the atmosphere will grow to greater intensities with stronger and more intense storms, accompanied by the risk of hail.
Research to back this claim up took place in the Amazon rain forest during the height of several forest fires. It indicated that small andnumerous smoke particles provide “nucleation sites” for cloud droplets. These droplets often smaller than traditional rain drops do not coalesce right away and thus the cloud is able to grow larger and larger in some cases in excess of 10km More often reaching above the freezing line and able to produce hail.
The PM stated no cloud seeding operations took place on Tuesday, yet all cloud seeding does is add more Condensation Nuclei in to the atmosphere.
Does this research confirm that the hail storm in Singapore was a result of the haze swamping the city? Possibly, but more research and post analysis will be needed in regards to the matter.
At the same time this hail storm al Indonesia was also conducting cloud seeding operations. This just adds another element to the possible cause of this weather anomaly. The stance of the NEA is that the hail in Singapore was not caused by cloud-seeding in Indonesia, and the rain in other parts of the island is not toxic.
The hail storm also caused high winds damaging trees and causing superficial damage in the western parts of the city. Despite the rain that came with it haze is still being reported in the area.
The initial ingredient to spark the storms in the Singapore area was also a switch in the winds from South West to North East. This triggered some moisture in the the region, the smoke very well likely enhanced the already developing thunderstorm.