Troposphere :  (noun)

1: the lowest atmospheric layer; from 4 to 11 miles high (depending on latitude)

Appleton layer, CAT, F layer, Heaviside-Kennelly layer, Van Allen belt, aerospace, aerosphere, air hole, air pocket, airspace, belt, bump, ceiling, chemosphere, crosswind, empty space, favorable wind, fog, front, head wind, high-pressure area, hole, ionosphere, isothermal region, jetstream, layer, low-pressure area, lower atmosphere, outer atmosphere, overcast, photosphere, pocket, roughness, soup, space, stratosphere, stratum, substratosphere, tail wind, tropopause, trough, turbulence, upper atmosphere, visibility, visibility zero,