Video instructions and help with filling out and completing Who Form 2220 Forecast

Instructions and Help about Who Form 2220 Forecast

Jet streams are another name for fast flowing currents of air there are many different jet streams that exist at both high and low levels in the atmosphere each has an important role to play in the weather experienced on earth the major jet streams that circle the earth are found just below the tropopause at a heights ranging from 9 to 16 kilometers and can reach speeds over 200 miles per hour they're hundreds of kilometres wide by only a few kilometers deep so often described as a ribbon of very strong winds the major jet streams are the polar front and subtropical jets these occur in both the northern and southern hemispheres and a part of the larger global circulation the polar front jet occurs over mid latitudes and strongly influences the weather over the UK in Europe the polar front jet is a type of thermal wind that arises due to the strong temperature contrasts between cold polar air and warm tropical air to explain this further imagine two columns of air one in the cold air to the north of the jet and one in the warm air to the south the top of each column is bounded by the tropopause a shorter column of cold air exerts the same surface pressure as a taller column of wor air this is because in the cold air column the air is more dense this causes atmospheric pressure to decrease more quickly with Heights in the warm air column pressure does not decrease as rapidly with height because the warmer air is less dense the tropopause in both columns is at the same atmospheric pressure so if you were to climb to the same heights in both columns you would find that you would be at a lower atmospheric pressure in the cold air column and a higher atmospheric pressure in the warm air column the pressure difference caused by this temperature gradient produces a pressure gradient force the pressure gradient force acts from high to low pressure so theoretically in the Northern Hemisphere air would flow from south to north but the Coriolis force resulting from the Earth's rotation causes the air to move to the right of the direction of motion in the Northern Hemisphere and to the left of the direction of motion in the southern hemisphere in both hemispheres the jet stream flows parallel to this temperature gradients moving from west to east theoretically this jet encircles the earth in a continuous line but in reality it is more broken up as differential heating of land sea masses lead to west to east temperature contrasts as well as north to south as the polar front Jets forms due to the temperature contrast the stronger the temperature gradient the stronger the Jets this means that the jet is stronger in the winter than the summer as the poles call during the winter months increasing the temperature contrast in the northern hemisphere the jet tends to be further south in winter and further north in summer this is due to the tilt of the earth and that in the winter the northern hemisphere is tilted away from the Sun and in the summer it is tilted towards the Sun mid latitude low pressure systems occur on the polar or northern side of the Jetstream while more settled warmer conditions are found to the south this gives us the wet and windy weather we often see in the UK during the winter months as low pressure systems are steered towards us it can also lead to some disappointingly wet summers with the Jetstream remains to the south of the UK a stationary jet stream pattern will bring frequent low pressure systems to the same region when warm air moves further north and normal or cold polar air moves further south this can change the prevailing west to east jet stream pattern this causes the jet stream to buckle driving depressions towards different regions or blocking their movements altogether a straight West East flowing jet stream won't have much impact on the development of new weather systems or strengthened pre-existing ones when a jet stream meanders north and south air accelerates and decelerates around the bends and the flow these areas of changing speeds are our development areas where the air is accelerating more air is leaving than entering a certain point this means that the air is being depleted at this point to fill the depletion air from below Rises when air rises it forms clouds and precipitation winds at the surface converge to this rising air column which causes surface pressure to fall and a low pressure system may develop or deepen further so whilst a jet stream is just an area of fast flowing air it has a fundamental effect on our weather Music you