Useful notes on Ice-Cap Climate (Fi) found over the continent of Antarctica

Location:

The ice-cap climate is found over the continent of Antarctica in the Southern Hemisphere. In the Northern Hemisphere this climate prevails over the permanently frozen parts of the Arctic Ocean, in the interior parts of Greenland, Iceland, Spitzbergen, and the arctic islands of Canada, and the U.S.S.R.

The ice-cap climate occurs over the largest area, covering about 15.5 million square kilometers. This climate is said to be the least known of the earth’s climatic types. There are only few weather observatories to supply climatic data, so that only fragmentary climatic data are available from these snow or ice deserts.

Temperature:

In the ice-cap climate the average temperature of no month is above 0°C. Thus, this climate records the lowest annual average temperature. The ice-cap climate has the unique distinction of being the coldest, especially in summer.

It is noteworthy that Vostok in Antarctica recorded the world’s lowest temperature of -88.3°C. Eismitte, Greenland has an average temperature of -40°C for winter months, whereas the average for the warmest month is about-11°C.

The main reason for the low temperatures of ice-cap climates is the fact that these regions receive the minimum amount of insolation. During half the year, there is practically no insolation received.

Even during the period of continuous daylight, sun’s rays are so oblique that whatever radiant energy is received, it is spread over a larger area so that little energy is received per unit area.

Besides, 80 per cent of solar radiation falling on the ice-cap surface is reflected back to space. The remaining 20 per cent energy is used in melting or evaporating snow and ice. Another factor which contributes to low temperatures in these regions is the elevation. Ice caps covering Greenland and Antarctica rise over 3000 meters above sea level.

Pressure and wind:

The ice-covered interior Antarctica and Greenland are under the influence of anticyclones which are thermally produced. Overlying the anticyclones, there are deep cyclonic vortices at still higher levels.

These are associated with high-velocity westerly winds. Since the arctic cyclonic circulation at stratospheric levels undergoes frequent disruptions both in winter and summer, there are outbreaks of cold and dense polar air towards south over Canada and Eurasia.

But in the Antarctica the upper-level cyclonic circulation is more persistent in winter. However, in summer whenever this circulation pattern weakens there may be occasional influx of relatively warmer air from the lower latitudes.

Precipitation:

Precipitation in the ice-cap climates is so little that these regions are called polar deserts. The average annual precipitation hardly exceeds 10 cm. Even though the precipitation is very low, it still exceeds evaporation.

Because of very low temperatures, the moisture holding capacity of air is also very low so that there is less evaporation. That is why the ice-cap climate may be considered as humid.

Moreover, there are other factors which are opposed to precipitation in these reigns, such as the stability of the air masses produced by strong surface temperature inversion, and the absence of upslope winds.

Almost all the precipitation is in the form of snow or as small crystals of dry and hard ice. The falling snow or ice particles are driven along by the high-velocity winds or they may be swept up from the ground.

Cyclones passing along the margins of the ice plateaus cause some precipitation which falls as a mist of powdered ice.

The information on precipitation and storms in these regions is only fragmentary. The natural surplus of precipitation produces glaciers which move out to the sea in the form of icebergs.

Natural vegetation and animal life:

The ice-cap climate is hostile to any form of vegetation because of permanent snow and ice and subfreezing temperatures. In fact, it is nearly a lifeless climatic region. But various kinds of fish, seal, walrus and semi-aquatic polar bears are found in large number in the sea.

Many varieties of aquatic birds like penguins inhabit coastal areas of Antarctica. On the pack ice of the North Pole seas there are a large number of polar bears which hunt various kinds of seal there.