SYN
CAT, aerospace, aerosphere, air hole, air pocket, airspace, apparentness, bump, ceiling, clearness, crosswind, crystal-clearness, distinctness, empty space, evidence, evidentness, favorable wind, fog, front, head wind, high-pressure area, hole, ionosphere, jetstream, low-pressure area, manifestness, obviousness, openness, openness to sight, overcast, overtness, palpability, patentness, perspicuity, plainness, pocket, roughness, soup, space, stratosphere, substratosphere, tail wind, tangibility, tropopause, troposphere, trough, turbulence, unmistakableness, unquestionability, visibility zero, visuality,