The tundra is found in the coldest areas on Earth. There are two types of tundra: (1) arctic tundra is found in the Arctic Circle where the North Pole is located and in the Antarctic Circle where the South Pole is located; (2) the alpine tundra is found on mountain ranges where trees can no longer grow (termed timberline). The winters in the tundra can be as low as -57 degrees Celsius (-126 degrees F), but the lowest ever recorded was -88 degrees Celsius.
The arctic tundra around the North Pole has winter temperatures averaging -34 degrees C, whereas the summer averages are usually around 3-12 degrees C. During the summer months the tundra, once covered in snow begins to melt, allowing 50-60 days of plant growth and the formation of small ponds or pools. Although much of the snow on the surface is melted during the summer, there is always a permanent layer of frozen soil beneath the surface called "permafrost." Animals able to survive these conditions include: reindeer, musk ox, hares, arctic fox, wolves, and many migratory bird species.
The arctic tundra surrounding the South Pole is very different. Actually it is not really tundra at all, but rather a cold desert that becomes covered by a solid ice sheet formed by the freezing ocean around the continent of Antarctica.
The alpine tundra is perhaps the most common to many because it occurs at high altitudes of the mountain. Here the temperatures are not as low as the arctic, but usually are always below freezing at night. The summer months contain a much longer period for plants to grow ranging about 180 days. Because temperatures are not as low as those of the arctic tundra, more animals are able to inhabit these areas. They include marmots, mountain goats, sheep, and upland ground birds.