1A cloud — a mass of tiny water droplets or ice crystals floating in the sky; a basic word commonly used when describing the weather.
空に白い雲が浮かんでいる。
White clouds are floating in the sky.
今にも雨が降りそうな黒い雲が広がってきた。
Dark clouds that look like they'll bring rain any moment have spread across the sky.
山の頂上が雲に隠れて見えない。
The mountain peak is hidden by clouds and can't be seen.
飛行機の窓から見る雲海はまるで絵のようだ。
The sea of clouds seen from the airplane window looks just like a painting.