inversion
From Longman Dictionary of Contemporary EnglishRelated topics: Meteorologyinversionin‧ver‧sion /ɪnˈvɜːʃən $ -ˈvɜːrʒən/ noun [countable, uncountable] 1 formalOPPOSITE/REVERSE the act of changing something so that it is the opposite of what it was before, or of turning something upside down (=the bottom is on the top and the top is on the bottom)2 technicalHEM a type of weather condition in which the air nearest the ground is cooler than the air above it