CAT, aerospace, air hole, air pocket, airspace, atmosphere, biosphere, bump, ceiling, crosswind, ecosphere, empty space, favorable wind, fog, front, gaseous envelope, head wind, high-pressure area, hole, ionosphere, jetstream, lift, low-pressure area, noosphere, overcast, pocket, roughness, soup, space, stratosphere, substratosphere, tail wind, tropopause, troposphere, trough, turbulence, visibility, visibility zero, welkin