Are meteorological proverbs reliable? Is there any scientific basis for predicting the weather by looking at the clouds?

Author: Science History Commentary Wu Jingping

When I was in middle school, I joined a meteorology interest group. I thought I would be able to get in touch with a lot of interesting instruments, such as thermometers, instruments for measuring dryness and humidity, etc. Meteorological observations always involve a louvered box, and I always thought the things in the box were quite mysterious. I have always had a strong interest in these hands-on gadgets since I was a child.

Photo: The interior of an old-fashioned venetian box

But I was quite disappointed later, because this meteorological group didn't do these things at all. The teacher told us that the district had a meteorological knowledge competition at that time. The school temporarily organized a few people to cope with this knowledge competition, and I was one of them. So our main job at that time was to memorize a lot of meteorological knowledge, that is, a lot of meteorological proverbs. At that time, the teacher also borrowed a very thick Chinese cloud atlas from the library. The whole book was full of large photos. From the perspective of landscape photography, the photos were really beautiful. From that thick album, I saw all kinds of strange clouds.

But in the end, this event ended in failure. Because there were too few participating schools, the competition was cancelled. So we spent so much time in vain. It was really frustrating to think that we memorized so many proverbs but could not use any of them.

Picture: There are hook-shaped clouds in the sky and it is raining on the ground

But by then, I had developed a habit of looking at the clouds in the sky and guessing how the weather would develop in the future. Anyway, I had memorized a lot of proverbs, and maybe one of them would come true. For example, "When there are hook-shaped clouds in the sky, it will rain heavily on the ground." There is another saying, "When there are hook-shaped clouds in the sky, it will rain heavily for three days." I actually noticed that if I really saw hook-shaped clouds at sunset, it would usually rain on the third day.

Figure: "Fish scale sky" is actually cumulus cloud

There is also a saying that goes "fish scale sky, no rain but strong wind". If you see rows of tiny clouds in the sky, neatly arranged like fish scales, the weather will soon turn bad. This is the so-called fish scale sky. I have actually encountered this kind of thing in Beijing. When I saw the fish scale sky, it rained not long after.

However, I never had the chance to see some of the scenes described in the proverbs in Beijing, such as "Red clouds pass overhead, quickly collect your boats". If you see this kind of sky phenomenon at the seaside, it often means that a typhoon is coming. A typhoon is actually a large low-pressure system, and its cloud system can extend to a very far range. Under the illumination of the setting sun, these clouds appear particularly bright and red. Therefore, fishermen around the South China Sea summed up this proverb.

Beijing is not a seaside city, so naturally you can't see this phenomenon. But I did see it once in Shanghai this year (2021). The power of typhoon fireworks is really strong, and they move slowly. The center of the typhoon is still far away, and the outer cloud system has already swept around Shanghai.

Picture: The gorgeous sunset before the arrival of the "fireworks"

Shanghai had a "crystal sky" with extremely clear and transparent air. The clouds in the sky were like running horses, and there was a brilliant sunset glow under the setting sun. You know, even the smaller clouds contain hundreds of tons of water. The mountain-like cumulonimbus clouds easily weigh millions of tons. These clouds trotted to Henan and Shaanxi. So this year, many places such as Henan, Shanxi, and Shaanxi suffered from floods. A few days later, fireworks landed on the southeast coast, and Shanghai was basically the first to bear the brunt. It rained heavily that day.

Therefore, weather forecast is very important to us humans. The ancients also wanted to understand the laws of weather changes, so there are so many proverbs. For coastal fishermen in the past, it was a basic need to read the clouds and know the weather. If you can't do this, you may not even save your life. These proverbs are still accurate to a certain extent, after all, they are the summary of long-term experience.

However, you can't rely solely on these proverbs to predict the weather. To be honest, these proverbs are sometimes effective and sometimes not. I don't have the ability to make accurate weather forecasts like Zhuge Liang did by observing the night sky. I have tried this myself. When I was in Beijing, I could barely guess half of the weather. When I arrived in Shanghai, the accuracy rate dropped sharply. It seems that these proverbs are also limited by region. Later, I simply gave up playing with them.

Well, let me summarize in one sentence: meteorological proverbs were summarized by the ancients using "big data". They embody the wisdom of the ancients in understanding nature and have a certain degree of accuracy, but are far less accurate than the weather forecasts based on big data in the information age.