albedo antarctica arctic arctic circle arctic shrinkage baffin island climate climate of antarctica climate of the nordic countries cold war continental climate cyclone desert diamond dust effects of global warming extratropical cyclone fridtjof nansen geologic temperature record glacier interglacial international polar year latitude north pole northern hemisphere northwest passage orographic lift polar climate polar exploration refraction remote sensing russia sea ice season severnaya zemlya shemya snow soviet and russian manned drifting ice stations storm track subarctic climate svalbard taymyr peninsula thermal radiation tree line verkhoyansk