Clouds formed this way are called cumulus clouds, or cumulonimbus clouds, and they usually lead to very heavy rain, often with thunder and lightning.

这样形成的云被称为积雨云，它们通常会导致大雨，还经常伴有电闪雷鸣。

There are five primary cloud types: stratus, cumulus, stratocumulus, cumulonimbus  and cirrus, each of which are subdivided into different genera based on altitude.

有五种主要的云类型：层云、积云、层积云、积雨云和卷云，每种云都根据海拔高度细分为不同的属。

Howard identified seven cloud types, but these have since been expanded to ten, cloud nine being the towering cumulonimbus thunder cloud, which is probably why being on cloud nine means to be on top of the world.

霍华德一共命名了七种云，现在人们已将其扩展为十种。第九种云是高耸的积雨云，这或许是为什么“在第九种云上”有登上世界之巅的意思。