WordNet (r) 3.0 (2006):

stratosphere
    n 1: the atmospheric layer between the troposphere and the
         mesosphere

Moby Thesaurus II by Grady Ward, 1.0:

67 Moby Thesaurus words for "stratosphere":
   Appleton layer, CAT, F layer, Heaviside-Kennelly layer,
   Olympian heights, Van Allen belt, acme, aerial heights, aerospace,
   aerosphere, air hole, air pocket, airspace, apex, belt, bump,
   ceiling, chemosphere, crosswind, dizzy heights, elevation,
   eminence, empty space, ether, favorable wind, fog, front,
   head wind, heaven, heavens, height, heights, high-pressure area,
   hole, ionosphere, isothermal region, jetstream, layer, lift,
   low-pressure area, lower atmosphere, outer atmosphere, overcast,
   photosphere, pocket, raise, rise, rising ground, roughness, sky,
   soup, space, steep, stratum, substratosphere, tail wind,
   tropopause, troposphere, trough, turbulence, upper atmosphere,
   uprise, vantage ground, vantage point, visibility, visibility zero,
   zenith