An "air column" refers to a vertical section of air that extends from the ground or a surface to the top of the atmosphere. It can be thought of as a column of air that is stacked on top of each other. Full definition
«We're monitoring on the ground and thinking that's representative of the entire air column — but I don't think that's true,» she says. (newscientist.com)
Burnt orange glow observed in the crater of volcano and in thick column of ash rising nearly two miles into the air (theguardian.com)
Tornado A violently rotating air column in contact with the ground and extending to the base of a thunderstorm. (discovermagazine.com)