What are the characteristics of "weather well"?

There is a well that can forecast the weather in the village of Slove in Sayer, Denmark. People call it a "weather well". At first, people didn't find anything strange about this well, but when people replaced the new manhole cover, they found that the manhole cover would whistle strangely before the weather changed. After careful observation, it is found that there is a small hole on the manhole cover, and the size of the small hole and the wellbore just constitute the structure of a whistle. When the weather changes, so does the atmospheric pressure. For example, when the weather gets worse, the low pressure front comes, the air rushes out of the well, and the small hole on the manhole cover whistles. When the weather improves and the air pressure rises, the well sucks in air and whistles. This phenomenon usually occurs about one day and night before the weather changes.

Later, the villagers tied a silk handkerchief to the hole in the manhole cover. On a sunny day, the handkerchief floated out of the manhole cover, indicating that it would rain the next day; When the handkerchief falls into the small hole, it means that the weather is about to clear up. Since then, whenever people want to go out or know the weather, they will come to the well to have a look.