Cold snow forest and polar climates (D, E)

Group D, cold snow forest climates, occur over large continental areas only in the northern hemisphere, between 40° and 70° N in Europe, Asia and North America. Winters grow harsher towards higher latitudes.

• Df, cold climate with humid winters: poleward of the marine west coast and mid-latitude steppe. Cold, snowy winters, a short frost-free season, large annual ranges, and abrupt, short weather changes.
• Dw, cold climate with dry winters: mainly north-eastern Asia. A strong winter anticyclone that weakens in summer gives a monsoon-like reversal of winds. Winters are extremely cold, with many places below freezing for up to seven months; rain falls in summer and is low, 12-15 cm a year.

Group E, polar climates, lie poleward of 70°:

• Tundra (ET): named after its vegetation of low-growing mosses, lichens and flowering plants. It is a region of permafrost, where the subsoil is permanently frozen. A short growing season and waterlogging allow only low plants. In summer the days are very long.
• Ice cap (EF): over interior Greenland and Antarctica. Temperatures stay below freezing even in summer; precipitation is very low. Snow and ice pile up until the pressure deforms the ice sheets and they break, drifting off as icebergs. (The book's example station is Plateau Station, Antarctica, 79° S.)

Example (new): a builder in a permafrost town must raise houses on stilts or insulated pads, because the warmth of a heated house would thaw the frozen ground beneath it and make the floor sink.