| The polar front is an area on the earth located at | | | | variances of the polar front below. However trapped |
| approximately 60 degrees north and south where | | | | inside this loop of clouds is the cold and clear air that |
| warm air circulating from the tropics meets cold air | | | | sits over the arctic ice. This huge volume of air is |
| plunging from the poles. The difference in | | | | very stable and has a key role in dictating the |
| temperature of these masses of air causes the | | | | weather further to the south. It is an air mass and |
| warm air to rise and most of this moves back | | | | with the long cold winter darkness and the extreme |
| towards the equator and sinks at around 30 degrees | | | | cooling caused by the ice beneath, this air mass |
| North and South, adding to the high pressure | | | | becomes ever more stable and progressively colder. |
| systems at these latitudes. | | | | The air mass has now formed a huge high pressure |
| The rest of the air that rises at the polar front | | | | dome over the arctic which remains until a change in |
| continues to move towards the poles and as it cools | | | | the jet stream causes part of this mass to slide |
| it sinks and returns back towards 60 degrees north | | | | southwards. |
| and south. However these flows of air do not move | | | | Over the North American continent there is nothing |
| in a direct north-south route. They are altered by the | | | | to stop the southerly movement of this extremely |
| rotation of the earth. This rotation will cause any | | | | cold air as there is nothing but flat, open land. This |
| freely moving object to appear to move to the right | | | | movement south is known as a polar surge. This |
| of the direction of motion in the northern hemisphere | | | | blast of icy cold air is huge and over North America |
| and to the left in the southern. This is known as the | | | | can reach as far south as Florida and Texas, |
| Coriolis Effect and explains why winds travel | | | | devastating crops and freezing land sometimes |
| clockwise around high pressure systems in the | | | | overnight. In 1983-84 a polar surge left almost 90 |
| northern hemisphere and anti-clockwise in the | | | | percent of the USA covered in cold air for nearly |
| southern, with low pressure winds travelling in the | | | | two months. In Utah a record low temperature of |
| opposite direction. | | | | -54 degrees C (-65 degrees F) was measured. |
| Jet Streams are formed at high altitudes where | | | | Unfortunately it was a polar surge in 1986 that |
| warm and cold air masses meet. Therefore the polar | | | | caused the destruction of the space shuttle |
| jet stream is located at 60 degrees north and south | | | | Challenger. On the morning of 28th January 1986 |
| approximately along the polar front. During winter | | | | large quantities of ice coated the launch pad at Cape |
| when the temperature difference is at its greatest | | | | Canaveral. NASA decided to go ahead with the launch |
| the jet streams will shift towards the equator, and | | | | despite the warnings from the manufacturers of the |
| during summer move back towards the poles. | | | | solid rocket boosters that the rings might not |
| A satellite view of the North Pole shows clouds | | | | perform their function of sealing possible fuel links at |
| carried from west to east around the rim of the | | | | such cold temperatures. Sadly the engineers were |
| Arctic by the polar jet stream. This ring of clouds will | | | | proved right as the world watched Challenger |
| fluctuate north and south depending on the pressure | | | | explode shortly after lift off. |