Cumulus is a kind of cloud: thick, white, and puffy, with a flat bottom and a lumpy top, like a heap of cotton or cauliflower. On a fair day you see them sitting separately in a blue sky.

Cumulus is a kind of cloudcumulus是一種雲：thick, white, and puffy又厚又白又蓬鬆，with a flat bottom and a lumpy top底部平平的，頂部則凹凸不平，like a heap of cotton or cauliflower像一堆棉花或花椰菜。On a fair day在晴朗的日子裡，you see them sitting separately in a blue sky你會看到它們一朵朵分開地掛在藍天上。

The Latin word meant a heap or a pile, which is exactly how they look. A British chemist, Luke Howard, gave clouds these Latin names in 1803, and weather people still use his system.

The Latin word meant a heap or a pile這個拉丁字原本的意思是「一堆」，which is exactly how they look而它們看起來也正是這樣。A British chemist, Luke Howard英國化學家Luke Howard，gave clouds these Latin names in 1803在1803年給雲取了這些拉丁文名字，and weather people still use his system氣象人員至今仍在使用他的分類系統。

Small friendly heaps are fair-weather cumulus; if they grow tall and dark they can turn into cumulonimbus, the thundercloud.

Small friendly heaps小小的、討喜的雲堆 are叫做 fair-weather cumulus晴天積雲；if they grow tall and dark如果它們長得又高又暗，they can turn into cumulonimbus, the thundercloud就會變成cumulonimbus，也就是雷雨雲。

Scientists and weather reports use the word; everyday people more often just say "fluffy clouds". Though actually, in older Latin cumulus was any heap, not only a cloud — the cloud sense is the one English learners meet.

Scientists and weather reports use the word科學家和氣象報告會用這個字；everyday people more often just say "fluffy clouds"一般人更常直接說蓬鬆的雲。Though actually不過其實，in older Latin cumulus was any heap, not only a cloud在更早的拉丁文裡，cumulus指任何一堆東西，不只是雲——the cloud sense is the one English learners meet但「雲」這個意思，才是英文學習者會遇到的。