The so-called Caiyun or rainbow cloud, the academic name is a horizontal arc around the earth, also known as solar load or solar genetic phenomenon. The formation principle of horizontal arc around the earth is caused by the refraction of ice crystals in the upper atmosphere under the irradiation of sunlight. The necessary conditions for generating a horizontal arc around the earth are: first, the height of cirrus clouds in the sky should be at least 20,000 feet; Second, the number of ice crystals in cirrus clouds should be sufficient; The third is the most critical factor. When the sun shines on cirrus clouds, the angle is higher than 58 degrees and lower than 90 degrees (some data also say it is 58-68 degrees). To meet the above three conditions at the same time, the rainbow arc phenomenon around the earth is a natural phenomenon with low probability. Oh, yes, on the afternoon of February 2 1 this year, a rainbow arc appeared in Singapore. At first, it was just a small orange circle, then it gradually expanded, and other colors appeared one after another, which lasted for about 15 minutes and then dissipated. The truth behind it is that because of inner helplessness, you need to constantly seek spiritual sustenance from external phenomena and artificially give various phenomena many colors, but in the end, you will find that you are still confused and worried when facing life. When people die, they should look at the color and shape of the clouds in the sky. Is it a big obsession? Is drawing a circle on a circle helpful to the growth of one's wisdom? Therefore, please spend your time studying the color and shape of clouds on studying and adjusting the state of your mind. When you look up, you will find that the sky is blue and beautiful no matter when and where. Finally, I want to say that when a real yogi hears the news of the monk's death, his first reaction will definitely not be to look up at the changes of the clouds, take out his mobile phone and take a photo, and then say "auspicious, auspicious", but to reflect on himself, whether he is really practicing Buddhism and his compassion, that's all.