thermal vs air current

thermal and air current both are nouns.

Word	Noun	Adjective	Verb	Adverb
thermal	Yes	Yes	No	No
air current	Yes	No	No	No

As nouns, air current is a hypernym of thermal; that is, air current is a word with a broader meaning than thermal:

thermal: rising current of warm air
air current: air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure

Other hypernyms of thermal include current of air, wind.

thermal (noun)	air current (noun)
rising current of warm air	air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure

thermal (adjective)	air current (adjective)
relating to or associated with heat
of or relating to a hot spring
caused by or designed to retain heat