The vertical speed of air is called

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.