Antarctica is covered with a sheet of ice. In the Arctic the pole is capped by deep ice floating on the sea and all the land north of the timber line is frozen. There are only two seasons - a long winter and a short summer - the day varying from complete darkness in midwinter to 24 hours daylight at midsummer. Arctic summer temperatures can rise to 18C (65F), except on glaciers and frozen seas, but fall in winter to as low as - 56C (-81F) and are never above freezing point. In the northern forests summer temperatures can reach 37C (100F), but altitude pushes winter temperatures even lower than in the arctic. Antarctic winds of 177kmph (110mph) have been recorded and , in the arctic autumn, winter winds reach hurricane force and can whip snow 30m (100ft) into the air, giving the impression of a blizzard - even when its not snowing. Accompanied by low temperatures, winds have a marked chilling effect- much greater than the thermometer indicates. For instance, a 32kmph wind will bring a temperature of -14C(5F) down to -34C(-30F)

Arctic Navigation

Compasses are unreliable near the poles, the constellations are better direction finders and nights light enough to travel by. By day use the shadow tip method. Traveling on sea ice , do not use iceberg's or distant land marks to fix direction. Floes are constantly moving - relative positions may change. Watch for ice breaking up and, if forced to cross from floe to floe ,leap from and to a spot at least 60cm (2ft) from the edge. Survivors have been rescued from floes drifting south but sooner or later ice floating into the warmer oceans will melt- though that chance might be worth taking.

Avoid iceberg's, they have most of their mass below the water. As this melts, they can turn over without warning, particularly with your added weight. Avoid sailing close to ice-cliffs . Glaciers may "calve" huge masses of ice , often thousands of tons, which break off into the sea without warning.

Bird observations can aid navigation . Migrating wildfowl fly to land in the thaw. Most sea birds fly out to sea during the day and return at night. Sky reflections help to determine distant terrain. Clouds over open water, timber or snow free ground appear black below ; over sea ice and snowfields, white. New ice produces grayish reflections, mottled ones indicate pack ice or drifted snow.

Warning : Ice cold water is a killer. Falling into icy water knocks the breath out of you. The body curls up with loss of muscular control and violent shivering. Exposed parts freeze in about 4 minutes, consciousness clouds in 7, death follows in 15 - 20. Resist! Take violent action on hitting the water. Get to shelter and dry kit immediately.