Acheronian, Acherontic, CAT, Cimmerian, Stygian, adumbrate, aerospace, aerosphere, air hole, air pocket, airspace, becloud, bedarken, bedim, befog, begloom, bemist, black, black out, blacken, blackening, blanket, block the light, blocking the light, blot out, brooding, brown, bump, cap, cast a shadow, castellatus, ceiling, cirrose, cirrous, clabber up, cloud-flecked, cloud, cloud over, cloud up, clouded, cloudiness, clouding, cloudy, crosswind, crown, cumuliform, cumulous, dark, dark and gloomy, darken, darken over, darkened, darkening, dim, dim out, dimming, dirty, dirty sky, dismal, dreary, dull, eclipse, eclipsing, empty space, encloud, encompass with shadow, enmist, extinguishment, favorable wind, fog, fogginess, front, funereal, gloom, gloomful, glooming, gloomy, grey, haze, haziness, head wind, heavy, heavy sky, high-pressure area, hole, ill-lighted, ill-lit, ionosphere, jetstream, lenticularis, low-pressure area, lowering, mammatus, menacing, mist, mistiness, murk, murky, nebulosity, nebulous, nimbose, nimbosity, nubilate, nubilation, nubilous, obfuscate, obfuscation, obnubilate, obnubilation, obscuration, obscure, obscurement, obumbrate, obumbration, occult, occultate, occulting, oppressive, overcloud, overclouded, overclouding, overlay, overshading, overshadow, overshadowing, overshadowment, oversmoke, overspread, pocket, roughness, shade, shading, shadow, shadowing, smog, smoke, somber, sombrous, soup, space, squally, starless, stormy, stratiform, stratosphere, stratous, substratosphere, sullen, sunless, tail wind, threatening, thunderheaded, tropopause, troposphere, trough, turbulence, visibility, visibility zero