The vertical speed of air is called

Answer: Option B

Air currents can be horizontal as well as vertical currents. The vertlcal air currents can be mechanically and thermally induced. Mechanically induced are the ones which occur at convergence & divergence points of air on earth, also locally when air rises vertically due to topography, while thermally induced vertical air currents occur when air expands & rises due to heat & the above lying cooler air comes down.