Author 'Gilbair' (Id 233560 ) : In reality, this 'green spot' is not a lake, but a pool of artificial water located at the summit of 'Mont d'or' at the franco-swiss border (French side). It probably serves as a reserve of water in the winter to feed snow guns to allow the use of runways that are not up to high enough altitude.
EXIF : IMGP9474. JPG ; Date : 22. 04. 2017; Model=PENTAX K-5
Artist=G. BENZONANA ; Copyright=B. G. ; Exposure Time=1/500 sec FNumber=F9. 0; ISO=400; Focal Length=18. 00 mm.