Tundra, besides the one I live in apparently, are very, very dry because of the cold. This means that it may be helpful to hibernate for the part of the year where it is even too cold for plants and other animals.
One definition of dry air is a theoretical sample of air that has no water vapor. Another definition of dry air is air that has a low relative humidity. When the relative humidity drops below about 40%, the air feels dry to the skin.
