Please enable JavaScript.
Coggle requires JavaScript to display documents.
WC5 - Global Weather Controls - Coggle Diagram
WC5 - Global Weather Controls
Jet streams
Subtropical
Jet sits 30-40º east between the hadley and ferrel cells, about 12-15 km high in the atmosphere
Polar front
Forms as a result of the temperature contrast across the polar front
Between the rising branches of the polar and ferrel cells at a height of 11-13km. It marks the boundary between cold air and warm tropical air called the polar front.
surface winds
trade winds
as air flows towards the equator it is deflected towards the west in both hemispheres (between 0 and 30 degrees)
prevailing winds
between 30º - 60º
The General Atmosphereic Circulation Model
The land surface around the equator is warmer than the poles
the tilt of the earth means that polar regions receive no daylight in the winter as rays are more scattered
ice and snow cause an albedo effect
At the poles, the solar radiation travels through a thicker layer of atmosphere, creating more opportunity for particles to absorb/ reflect the heat before it reaches earth, the radiation that reaches the earth hits earth at a lower angle so is spread over a larger area, which means it will be cooler at the poles as sun rays are less concentrated.
at the equator the radiation is more direct/concentrated, going through a shorter piece of atmosphere, meaning it will be warmer
warm air rises away from the earth, carrying moisture (water vapour) with it
In air (because its gas) the molecules can spread out more as they are not locked together
This means they rise upwards, so they aren't pressing on the earths surface, causing low pressure
When you heat something, the molecules move around more and spread out
cool, dry air sinks back down to earth, as all the moisture has condensed out of it in the atmosphere
In air (because its gas) the molecules are cooler in the poles as they are not locked together
This means they don't move & settle, so they are pressing on the earths surface, causing high pressure
When you cool something, the molecules move around less and group together
The tri-cellular model
polar, ferrel hadley cells
Intertropical convergence zone
the meeting place of the trade winds from both the northern hemisphere and the southern hemisphere
a low pressure area where the trade wins, which have picked up latent heat as they crossed oceans are forced to rise by convection currents
the risng air at the ITCZ leads to a circular air movement caused by the coolings of the air, called the coriolis effect
where the hadley cells meet
The tri-cellular diagram is only correct for 2 seasons of the year, this is when the incoming solar radiation is focused on the equator itself. in terms of seasons this created the Northern hemisphere spring/Southern Hemisphere autumn and vise versa
anticyclone (high pressure)
winds tend to be light and blow clockwise (in the northern hemisphere). the air is descending, which reduces the formation of clouds and leads to light winds and settled weather conditions
depression (low pressure)
Air risng and blows anticlockwise (in the northern hemisphere). As it rises and cools, water vapour condenses to form clouds and perhaps precipitation. this is why the weather in a depression is often unsettled, there are usually weather fronts assosiated iwth depressions.
coriolis effect
Instead of circulating in a straight pattern, the air defects towards the right in the northern hemisphere and the left in the southern hemisphere, resulting in curved paths.