Quiz: Remember the definition of mal de mer?
"field of granular snow, firn," 1843, from French névé (19c.), probably from Savoyard névi "mass of snow," from Latin nivem (nominative nix) "snow" (cf. French neige), from PIE root *sneigwh- "snow, to snow" (see snow (n.)).
partially compacted granular snow that is the intermediate stage between snow and glacial ice. Firn is found under the snow that accumulates at the head of a glacier. It is formed under the pressure of overlying snow by the processes of compaction, recrystallization, localized melting, and the crushing of individual snowflakes. This process is thought to take a period of about one year. Annual layers of firn may often be detected by thin films of dust or ash that accumulate on the surface during each summer.