The snow cover of a mountain range can be temporary or permanent through the year, depending on local altitude, latitude, and climate. When permanent, the snow is said eternal, meaning all or part of the snow cover transforms into a snowfield then a glacier. Otherwise, as on the summit ridge of the Puy de Sancy, temporary snow disappears either by melting when the temperature rises above 32°F (0°C) or by sublimation (transformation into gas) at temperatures below the melting point.