Polar climate

Coastal regions of Greenland that do not have permanent ice sheets have the less extreme tundra climates.

These subantarctic lowlands are found closer to the equator than the coastal tundras of the Arctic basin.

In winter, this relatively warm water, even though covered by the polar ice pack, keeps the North Pole from being the coldest place in the Northern Hemisphere, and it is also part of the reason that Antarctica is so much colder than the Arctic.

In summer, the presence of the nearby water keeps coastal areas from warming as much as they might otherwise, just as it does in temperate regions with maritime climates.

Summits of most mountains also have polar climates, despite being in lower latitudes, due to their high elevations.

Climatologist Wladimir Köppen demonstrated a relationship between the Arctic and Antarctic tree lines and the 10 °C (50 °F) summer isotherm; i.e., places where the average temperature in the warmest calendar month of the year is below the fixed threshold of 10 °C (50 °F) cannot support forests.

In the Southern Hemisphere, all of Tierra del Fuego lies outside the polar region in Nordenskiöld's system, but part of the island (including Ushuaia, Argentina) is reckoned as being within the Antarctic under Köppen's.

If the mean biotemperature is between 1.5 and 3 °C (34.7 and 37.4 °F),[5] Holdridge quantifies the climate as subpolar (or alpine, if the low temperature is caused by elevation).