1.
steam; water vapor
Water in its gaseous state, produced by heating or boiling. Used in both scientific and everyday contexts for the invisible gas or the visible mist produced when water evaporates or boils.
お湯から水蒸気が上がっている。
Steam is rising from the hot water.
水蒸気が冷えて水滴になった。
The water vapor cooled and turned into droplets.
火山の噴火口からは大量の水蒸気が噴出していた。
A large amount of steam was gushing from the volcanic crater.
USAGE:
In everyday Japanese, 水蒸気 refers to both the invisible gaseous state of water and the visible white mist (which is technically tiny water droplets). In scientific usage, 水蒸気 strictly means the invisible gas. The word 湯気 is the everyday term for visible steam rising from hot liquids.
COMMON COLLOCATIONS:
- 水蒸気が発生する: steam is generated
- 水蒸気爆発: steam explosion (phreatic eruption)
- 水蒸気を含む: to contain water vapor
- 大気中の水蒸気: atmospheric water vapor