People in Taitung County were treated to the "halo" optical effect around 11 a.m. on Apr. 28. A rainbow-colored halo appeared around the sun and lasted about one hour. The Central Weather Bureau says halos are produced by sunlight interacting with ice crystals suspended in the atmosphere, and this optical effect normally appears when the season is changing.
People in Taitung County got to see a wonderful "halo" optical effect around 11 a.m. on Apr. 28. The effect lasted about one hour. Many people stopped what they were doing, raised their heads to the sky, and took in the magnificent sight.
(Did you wonder what this strange sight was?) Yes.
The Central Weather Bureau says water vapor turns to ice crystals in clouds at 8,000 meters due to low temperatures. When the colorless sunlight passes through these ice crystals, it will refract or reflect a ring of rainbow-colored light. This is called the "halo" optical effect, because a halo of light appears around the sun. When this effect appears, it means the water vapor is abundant at the high altitude. This time, the halo was extensive and evenly distributed.
The clouds have to be thin, and you have to be able to see the sun. The hexagonal ice crystals around the sun refract the light. If the weather remains sunny and cloudless these next several days, and cirrostratus clouds appear around the sun, the probability of the halo optical effect occurring is higher.
The Central Weather Bureau adds the halo optical effect typically occurs when the season changes. In other weather-related news, the first plum rain front is forecasted to arrive on May 1 or 2. All of Taiwan is expected to see rain, and the northern and northeastern parts may see heavy rain, so the public is reminded to stay vigilant.