Rare rainbow cloud spotted in Brunei skies

Izah Azahari

A cloud awash with rainbow colours was briefly sighted at around 6pm on June 4, in the skies over Rimba, Gadong.

The Brunei Darussalam Meteorological Department (BDMD) released a picture of the rainbow cloud, along with a scientific explanation for the rare phenomenon, known as iridescence: “Iridescence is when colours appearing on the clouds are sometimes mingled and sometimes in the form of bands nearly parallel to the margin of the clouds.

“Green and pink occur most often, and in pastel shades. The iridescent hues are often brilliant, resembling the colours observed on mother-of-pearl.

“Within about 10 degrees from the Sun, diffraction is the main cause of iridescence. Beyond about 10 degrees, however, interference is usually the predominant factor. Iridescence can extend to angles exceeding 40 degrees from the Sun, and even at this angular distance, the colours may be brilliant.

“In Brunei, the phenomenon is not frequently observed and tends to occur during fair weather, accompanied by some high clouds.

“The picture shows iridescence occurring in the semi-transparent cirrostratus clouds made of tiny ice-crystals, which scattered the light.”

The rare rainbow cloud phenomenon in Brunei skies. PHOTO: BDMD

Meanwhile, the country is transitioning from Inter-monsoon to Southwest Monsoon which is expected to start this week. The general light wind, blowing from various directions will shift to the Southwest direction.

Atmospheric conditions tend to be quite stable with minimal thundershower occurrences as compared to the inter-monsoon period during the past two months. Southwest Monsoon typically lasts up until September. During the peak of the monsoon period – around August – the country usually experiences hazy conditions due to the generally dry weather across the Southeast Asian region.

Southwest Monsoon also coincides with the season of active development of cyclonic systems, such as tropical storms and typhoons, over the Northwest Pacific Ocean and South China Sea.

When such a system develops, depending on the location of the system in relation to Brunei, the country tends to experience unsettled weather conditions with occasional gusty thunderstorms.

The BDMD will continue to monitor the weather conditions and issue weather advisory or warnings if necessary.

The department advised the public to keep up to date with weather information and they can also learn about the different types of clouds observed in the country by visiting www.met.gov.bn, follow Facebook or Instagram (@bruneiweather), and the Brunei WX mobile application.

The public may contact the Duty Meteorological Forecasters at the BDMD Forecast Centre, through the Weather Line at 114. The BDMD also welcomed cloud enthusiasts to share their collection of photos, via its social media account.