This article aims at conceptually clarifying the notion of ambiance, which, following the work of Schmitz, Böhme and Griffero, has blossomed in the European scholarship over the last twenty years. The author chose to compare atmosphere and aura in order to identify two models of atmospheric diffusion of a feeling: the radial, by which the atmosphere emanates from a precisely identied source, and the medial, by which it pervades the space without signaling its particular origin. The aura is thus accounted for as an atmosphere that immediately heralds its point of emanation and always retains something within itself of the individuality, be it that of a person, an object, a place, an event, etc.