The valley mists - which the residents of the Saint-Claude region regularly experience in the early mornings of the winter season - are one form of meteoric water. These atmospheric waters - whether evaporated, condensed into drops and clouds, or crystallized into ice or snow - have been lifted from the earth's surface and remain suspended in the air. Their re-deposition is at the origin of the dew or the frost which enchant the Haut-Jura landscapes.