doldrums vs air current

doldrums and air current both are nouns.

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

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

doldrums: a belt of calms and light winds between the northern and southern trade winds of the Atlantic and Pacific
air current: air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure

Other hypernyms of doldrums include current of air, wind.

doldrums (noun)	air current (noun)
a belt of calms and light winds between the northern and southern trade winds of the Atlantic and Pacific	air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure
a state of inactivity (in business or art etc)