Frozen lakes may appear incompatible with life.  But "life" begs to differ. Any ice fisher will be happy to list the fish they have caught and the fish are exquisitely adapted to life beneath an icy ceiling. Learn how a quirk of water's physical chemistry makes life possible at 39 degrees. In summer, lakes are stratified into warm layers on top with colder layers below. Frozen winter lakes and ponds are coldest on top and warmer below; this is called inverse stratification.