Q. Is air a good conductor?
A. No; air is a very bad conductor.
Q. How is air heated?
A. By “convective currents.”
Q. What are meant by “convective currents?”
A. When a portion of air is heated, it rises upward in a current, carrying the heat with it: other colder air succeeds, and (being heated in a similar way) ascends also; and these are called convective currents.
(“Convective currents;” so called from the Latin words, cum-vectus (carried with) because the heat is “carried with” the current.)
Q. Is air heated by the rays of the sun?
A. No; air is not heated (in any sensible degree) by the action of the sun’s rays passing through it.
Q. Why then is the air hotter on a sunny day, than on a cloudy one?