KATHMANDU: A multi-coloured halo was seen encircling the sun from central and western Nepal for a few hours on Wednesday afternoon, making people glance up and talk about it with others. Many took photographs and posted them on social media sites Twitter and Facebook also. With patches of thick clouds floating below, when the sun was ascending to and descending from the zenith, the ‘rainbow ring’ appeared till 1:00 pm in Kathmandu Valley. The skies of Parsa, Chitwan, Nawalparasi, Dhading, Gorkha, Kaski and Lamjung districts were graced with the extraordinary optical phenomenon, which experts say is comparable to rainbows, from 11:30am to 3:00pm. People posted photographs from some eastern districts including Dolakha also. Such halos are visible when sun rays are refracted by a thin layer of high clouds containing ice crystals, Barun Paudel, a meteorologist at the Weather Forecasting Division, explained. The phenomenon may include refraction and reflection of light thereby dispersing the seven colours of light when it passes through the layer. The halo disappears and the sun is blocked when the ice crystals fuse together and make the clouds dense. A halo around sun is not very common as its formation requires high clouds called cirrostratus at an altitude of 13 km from the earth’s surface and clear skies below, Paudel said. It may be seen, though on the odd occasion, in Nepal during monsoon for such requirements could be met when there is no rainfall or dense cloud close to the earth’s surface. The halo around the sun is called Indrasabha and the phenomenon Sabha Baseko in Nepali with a connotation of the court of rain god Indra. Rainbow, on the other hand, is called Indreni or Indradhanusha, the bow of Indra. “I had seen rainbow ring around the sun a couple of times in the past,” Aavaas, a resident of Kathmandu said, reminiscing his childhood days. “Old people used to say then that it was a bad omen, but interestingly people in many communities in the high hills and Tibet consider it a good sign.” The interpretation of this natural event is as colourful as its display, the noted musician quipped. The halo was visible from Dolakha to Lamjung – in the stretch of 350 km or so – because the phenomenon was courtesy to the high clouds and the weather was fair in the region that time, according to Paudel. Similar halos are seen around the moon also in the evenings and are more common.