20 terms

Global Wind System

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Warm air
less dense, more buoyant, air is able to hold a greater amount of other atmospheric components such as water vapour. Therefore, areas of warm, rising air have low pressures.
Cold air
more dense, less buoyant than warmer air, less able to hold water vapour and other atmospheric pressures
Wind systems
result from the necessity to equalize pressures on the earth's surface. Rising air in low pressure areas must be replaced by air flowing in from high pressure areas. -winds always flow from areas of high pressure to areas of low pressure.
Pressure gradient
the difference in pressure of the wind
Low pressure
results in the uplift of air and production of storms
High pressure
creates downward moving air and results in no precipitation and little cloud = good weather
Coriolis force
due to the spinning of the earth on its axis, atmospheric movement in the northern hemisphere is deflected to the right, while movement in the southern hemisphere is deflected to the left
Wind direction
wind is labeled where it comes from, low and latitude winds (and polar winds) tend to get a northerly component, while mid-latitude winds get a southerly component
Conservation of angular momentum
gives the east and west component to winds, as the earth is rotating west to east, so is the atmosphere above it. The rotation rates should be the same, but when it is not the result is east or west winds.
West wind
the rotation of the air is faster than the rotation of the earth
East wind
the rotation of the air is less than the rotation of the earth
Subtropical highs
Air rises in equatorial regions begins to flow at high altitudes north and south, meet winds flowing towards the equator at the same altitude, then forced downward creating high pressure
Northeast & Southeast trade winds
the air flowing towards the equator
Westerly winds
the air flowing towards the poles. The westerlies flowe poleward along the surface and meet surface winds flowing out of the high pressure zones at the poles.
Sub-polar lows
the convergence of the surface westerlies traveling poleward converge, as a result of the flow of these various winds, three distinctive cells of air movement exist in each hemisphere.
High altitude winds: the jetstream
most important high altitude winds, travel at approximately 9-12km, they mark the division between cold polar air and warm tropical air, strong winds in upper troposphere
Atmospheric circulation
redistributes heat over earth's surface by exchanging warm tropical air with cold polar air.
Hadley cell
as air lifts and cools to the temperature of surrounding environmental air, uplift ceases and the air begins to move away from the equator
Ferrel cell
air traveling away from the Hadley cell (warmer) and the polar cell (colder) converge in the mid-latitudes to form the Ferrel cell
Polar cell
cold, dense arctic air that creates a high pressure zone, flows outwards due to pressure gradient winds and converges with the Ferrel cell