Q. Lakes freeze in cold countries in winter, leaving the water underneath at__:
Answer: 4°C
Notes: Ice cover in lakes is seasonal and occurs where average daily temperature is below the freezing point. Once formed the lake ice thickens over the course of the winter as the temperature gets colder. The lakes thermal structure prepares for ice with 0°C water at the surface and denser 4°C at the bottom. Once meteorological conditions provide colder air, relative to warmer water, the water does not get colder - instead freezes into ice.