What's the connection between clouds and weather?

We usually divide clouds into three categories, namely cumulus clouds, stratus clouds and cirrus clouds. According to these cloud phases, people have some reliable experience in forecasting the weather changes in the future 12 hours. Generally speaking, if fluffy cumulus clouds are very dispersed, it can be said that it is sunny, but if the clouds expand or have new development, it means that there will be sudden heavy rain. For example, cirrocumulus, often called "Fish Scale Day", looks like ripples, which generally indicates sunny weather. Semi-transparent cumulus clouds, like carp spots, generally indicate that it will clear up in a short time. Hook-hook cirrus indicates rain. Fortress-like altocumulus and stratocumulus indicate a thunderstorm. Cumulonimbus clouds often bring strong storms and lightning.