JAKARTA: Red skies seen over Indonesia's Jambi province at the weekend amid worsening haze was due to a phenomenon called Mie scattering, said the Meteorology, Climatology and Geophysics Agency (BMKG).
The agency explained on Sunday (Sep 22) that the coloured sky was caused by scattering of sunlight by micro particles called aerosols that float in the air.
BMKG said the phenomenon occurred when diameter of the aerosols is about the same as the wavelength of visible sunlight.
“Red light has a wavelength of 0.7 micrometres. Based on BMKG data, the concentration of pollutant particles measuring less than 10 micrometres was very high in Jambi, Palembang and Pekanbaru but only the sky in Muaro Jambi turned red," it said.
“This means air pollutants there have a high concentration of 0.7 micrometre particles.”
The Muaro Jambi district was cast in an alarming hue of orange-red, as worried residents posted videos and photos of the rare phenomenon on social media.
Twitter user Zuni Shofi Yatun Nisa said: “This is afternoon, not night. This is Earth not Mars. This is Jambi, not outer space. We are breathing with lungs, not gills. We humans need clean air, not smoke.”
Sharing a video from his friend, another Twitter user Rizal Wahid wrote: “This is noon. Come on, let’s stop arguing for a moment. There are hundreds of thousands of human lives at stake.”
Forest and peat fires in Indonesia have been sending haze to neighbouring countries in Southeast Asia in recent weeks.
Health Minister Dzulkefly Ahmad said last week that number of outpatients at government hospitals has increased between 20 and 30 per cent since the haze hit.
In a visit to Riau province last week, Indonesian President Joko Widodo ordered stern actions against individuals and companies responsible for forest fires.
Meanwhile, seven helicopters have been deployed to water bomb hotspots in South Sumatra province since Sunday as hotspots rose to more than 700, according to news site Tempo.
The two districts with the highest hotspots were Ogan Komering Ilir and Musi Banyuasin, with 251 and 159 hotspots respectively.
Tempo also reported that haze in Palembang – capital of South Sumatra – might worsen due to wind from the east-southeast direction, said Palembang Airport BMKG.