Beijing has recently experienced a "three-day sky storm"? Is it too late to dehydrate now?

Recently, the news #Three suns appeared in the sky in Beijing# became a hot search

Netizens also shared their own photos of the magical scene

Image source: Xiaohongshu

Seeing this phenomenon

Many people thought of the "three days in the sky" written in "The Three-Body Problem"

How come no one told me I was dehydrated?!

So, why are there three suns in the sky?

This complex halo landscape actually includes a large halo (46°), a small halo (22°), sundogs, sundog rings and a circumzenithal arc.

The small halo (22°) surrounding the sun and the sun dogs on both sides are relatively clear. The sun is surrounded by a small brown halo, and it seems as if there are two more suns on both sides.

In fact, there are more halo phases. If you observe carefully, you will find a larger halo (46°) on the periphery , and a circumzenithal arc like an inverted rainbow on the top of the large halo. If you observe more carefully, there seems to be a white ring passing through the three suns, which is the sun dog ring. Because this phenomenon lasted for a long time and changed greatly, some people also photographed the halo on the small halo .

Image source: Xiaohongshu

Halo (pronounced the same as "yun") refers to the optical phenomenon of various shapes and shapes such as colored circles, white rings, light arcs, and light spots that appear in the sky when sunlight or moonlight passes through clouds composed of ice crystals.

In ancient times, dizziness was considered an ominous sign. The idiom "a white rainbow piercing the sun" comes from "The Strategies of the Warring States": "When Nie Zheng assassinated Han Kui, a white rainbow pierced the sun." The white rainbow here refers to the sun phantom ring or sun pillar passing through the sun. Due to the lack of scientific knowledge of natural phenomena, people superstitiously believed that the sun represented the king, and the appearance of a white rainbow passing through the sun was an ominous sign.

It is common to see large or small halos in the sky. Sometimes they appear around the sun and are called solar halos, and sometimes they appear around the moon and are called lunar halos. There is a saying: Solar halos mean rain at midnight, and lunar halos mean wind at noon. This means that when halos appear in the sky, there may be wind and rain in the next 12 hours.

Scientifically speaking, this makes sense, because halos appear on cirrus and cirrostratus clouds, which are composed of ice crystals. Before a weather system arrives, cirrus and cirrostratus clouds are often distributed in front of it . The appearance of halos indicates that the front of the weather system has arrived, and it can be predicted that wind and rain may occur within the next 12 hours.

Since cirrus clouds and cirrostratus clouds are composed of ice crystals about 20 microns in size, the shapes of the ice crystals are varied. The most common shapes of ice crystals are hexagonal plates, columns, piles, and caps.

When sunlight and moonlight pass through ice crystals, they refract and form colorful large and small halos. Sometimes, under weak conditions, brown or white halos are formed.

Because ice crystals come in many shapes, different shapes of ice crystals or groups of ice crystals can also produce various halo phases, such as rings, arcs, columns, spots, and halos. Usually we often equate halos with haloes, but in fact, the two are not exactly the same. Among atmospheric optical phenomena, halos have the most members, and halos are only a common type. Other halo phases include colorful arcs, columns, spots, and halos.

The circumzenithal arc that appeared yesterday had a color distribution like an upside-down rainbow. The circumzenithal arc has clear and bright colors, although it looks smaller than a rainbow and lacks the momentum of a long rainbow. In addition, it appears at the zenith and generally attracts little attention.

Halos can be said to be the most complex and diverse type of atmospheric optical phenomena. It is far from enough to be familiar with large and small halos.

According to records, seven suns appeared in the sky above the Polish city of Stansk at 11 a.m. on February 20, 1661. Astronomer Hevel recorded this halo in his book "Mercury Alone on the Horizon", and this "Seven Suns Chart" became the first document on "multiple suns appearing simultaneously".

The haloes in this "seven-day panorama" are dazzling and disorienting. In this optical phenomenon, not only a small halo of 22° and a large halo of 46° appeared, but also six sun dogs, sun dog rings, circumzenithal arcs, sun pillars, halo prominences, etc. It is truly a "colorful gathering".

Seven-day panoramic view of the sky full of halos (Dai Yunwei/composition)

These magical halo landscapes in the sky are a visual feast given to us by nature, and are also an endless treasure for scientific exploration. Everyone should look up at the sky more often, because one day you may witness a natural wonder that is more exciting than a science fiction blockbuster.

Author: Dai Yunwei, Meteorological Film and Television Center, China Meteorological Administration

Editor: Dong Xiaoxian

Reviewer: Liu Kun and Li Peiyuan