升温
shēng wēn · HSK 7
to become hot
🌡️🔥 升温 = 升 (rise) + 温 (warm) = temperature rises; also figuratively heats up
升 — ladle/scoop pictograph (related to 斗)
升 originally pictured a ladle or dipper used to measure grain, closely related to 斗 (a larger dipper). It came to denote a unit of dry measure (a 'sheng', about a liter). From 'scooping up' it extended to the meaning 'rise, ascend'.