热气
rè qì · HSK 7
heat
♨️ 热气 = 热 hot + 气 air/gas; hot air rising off something = steam
热 means hot and 气 means air or gas, so 热气 is literally hot-air: the steam or heat that lifts off a boiling pot or hot bath. Measure word 股 gǔ counts a wisp or stream of it.
热 — 执 zhí (phonetic) + 灬 fire radical
热 is a semantic-phonetic compound: the bottom 灬 (a variant of 火 'fire') gives the meaning of heat, while 执 on top supplies the sound. Originally written 熱, it depicted fire below a phonetic element, and the meaning naturally extended from physical heat to 'hot' weather and 'enthusiastic' feelings.
气 — steam/vapor radical 气
Originally a pictograph of rising vapor or clouds drifting in the sky, depicting curling streams of air. The character came to mean breath, air, and by extension vital energy or 'qi.' The simplified form 气 keeps the original outline; the traditional 氣 added 米 (rice) to suggest steam rising from cooking grain.