CAT aerospace aerosphere air current air hole air pocket airspace backing wind beam wind bump ceiling crosscurrent crosswind current current of air downdraft draft empty space fair wind fall wind favorable wind flow of air fog following wind front head wind high-pressure area hole indraft inflow inhalation inrush inspiration ionosphere jetstream katabatic wind low-pressure area monsoon movement of air overcast pocket relative wind roughness slant of wind soup space stratosphere stream stream of air substratosphere tropopause troposphere trough turbulence undercurrent updraft veering wind visibility visibility zero wind