The moment the lid came off, steam hit me in the face.
Tips
mistakes
This is moisture in the air, invisible or showing as fog on a window. 蒸汽 is steam driven off by boiling, the industrial kind that turns a turbine. Physics writing uses the full 水蒸气 when the state of matter is the point.
memory
汽 is 气 with water added on the left, and it means vapor specifically rather than air or gas in general. The same character sits in 汽车, named in the steam era, and 汽水, fizzy water.
