In the sub-Arctic or tundra (E), the winters are very long and very cold. Vast areas of Canada, northern Russia and Siberia, extending to the Arctic, are far from the influence of mild winds off the sea. Short, often hot summers are followed by longer intensely cold winters. The annual range of temperatures is greatest in these regions. Verkoyansk in Siberia has recorded -70 degrees C in winter and +37 degrees C in summer. Forests of coniferous trees, or Taiga, are common as they can survive the extreme cold and are not damaged by snow.

Near the North and South Poles, in Greenland, Antarctica, and land inside the Arctic circle, the polar climate (F) is dominated by low temperatures, frequent strong winds and year round snow cover. In all months temperatures are near or below freezing point. Polar regions are dominated by snow and ice. Some parts of Antarctica are covered with a layer of ice more than 3,000 m (10,000 ft) thick. This is the harshest climate on Earth and the lowest temperatures are recorded in these areas - the record being -88 degrees C (-126 degrees F) at Vostock, a Russian research station in the Antarctic.

Mountain climates (G) occur in all major ranges where land rises above or near the permanent snowline, generally exceeding 3,000 m (10,000 ft) in height. Mountains create their own climate, no matter where they are located. The climate of a mountain or mountain range can be divided vertically into a number of sub-zones. While foothills may have a tropical climate, peaks may be covered in ice. The sub-zones of a mountain climate get progressively colder with increased altitude. The vegetation on the lower slopes largely depends on which climate zone the mountain is in. On the upper slopes, needleleaf trees reach to the tree line. Above this level are found alpine plants which can withstand the harsh conditions. The uppermost level is bare rock and snow. Tibet and the Himalayas and other mountain ranges such as the Rocky Mountains or the Andes are good examples of this. In Africa, only the isolated peaks of Mount Kenya and Kilimanjaro and the Ruwenzori range are high enough to carry permanent snow.