What does the agricultural proverb "a rainy mountain wears a hat, but a rainy mountain has no waist" mean? Is there a scientific explanation for this phenomenon?

Meaning: Clouds appear on the top of the mountain and it will rain, but clouds appear on the mountainside and it doesn't rain.

Scientific basis: the cloud covering the top of the mountain is called "the mountain wears a hat", and the top of the mountain where the cloud does not live on the mountainside is called "the mountain has no waist". When it rains, because the clouds are dark and low, they often press down the hills and form a "capped mountain", so it is a precursor to rain. But if the clouds don't fall and get lower and lower after wearing the hat, it won't necessarily rain, especially after the rain, the clouds gradually rise and form a trend of leaving the top of the mountain. This situation is called "hat rise". It does not indicate the arrival of rain, but indicates that the weather will improve. Most of the "waist clouds" are low clouds such as local stratum clouds formed by radiation cooling at night, which are probably fog halfway up the mountain, so the waist clouds are generally a symbol of good weather.