The temperature at the bottom of Lake Tahoe in the Sierra Nevada mountains of California is 4 degrees Celsius all year round. In which country is the water at the bottom of lakes normally higher than this?

The correct answer is c) New Zealand.

In New Zealand, many lakes experience higher bottom temperatures compared to the consistent 4 degrees Celsius found at Lake Tahoe. The warmer climate and geothermal activity in certain regions contribute to milder water temperatures at the lake bottoms. For instance, lakes near volcanic areas may exhibit warmer thermal layers, influencing overall lake temperature profiles.

In contrast, Russia, Great Britain, and Tibet tend to have lakes that maintain colder temperatures at their bottoms due to their geographical and climatic conditions. For example, the extreme cold in many parts of Russia leads to much lower temperatures in its lakes.