hello welcome back by the end of this video you should be able to explain the global atmospheric circulation model and you should be able to explain how circulation cells transfer heat energy around the world the sun acts as a heat source for our planet heat causes water to evaporate this is the change from a liquid to water VIP which is a gas heat causes that to rise and this Rising air contains water vapor the equator is a line which spreads around the center of the world this Lane is imaginary and in reality there is no line around the center of the world the earth's equator gets a bigger share of the sun's Rays than anywhere else in the world this means a large amount of moist air rises here after warm wet air has risen more air from elsewhere rushes in to replace the air which has been displaced once the air has risen to the top of the atmosphere it spreads out on top of the air which is rushing in to replace it during this time the air loses energy and the water vapor condenses to form clouds which eventually fall as rain sleet or snow and we'll call this precipitation we call areas where this process occurs low pressure areas at low pressure areas precipitation is common so they attempt to have wet climates with high rainfall eventually as the air loses more energy it cools down the cooler air then falls back to the Earth's surface we call these areas high pressure areas here rainfall is much less common so you tend to have arid climates and arid is just another name for dry this is because there is a lack of warm moist air which means it cannot cool down and fall as rain the falling air then spreads out again in forms of Loops of air movement which we call cells it is this movement on the surface which will feel as wind now the Earth is a sphere and it has angles zero degrees at the equator 30 degrees 60 degrees and 90 degrees at the poles cells operate around the world as we've just seen these cells are given names the Hadley cell takes warm air from the equator at zero degrees and moves at 30 degrees north and south of the Equator it also takes cool air from 30 degrees north and south to the equator the feral cell takes warm air from 60 degrees north and south and moves it to 30 degrees north and south it also removes cool air from 30 degrees to 60 degrees the Polar cell moves slightly warm air from 60 degrees north and south and it moves it to the poles of the Earth it also removes cold air from 90 degrees back to 60. because these cells operate all around the world we get pressure bands at zero degrees or the Equator we have a low pressure band at 30 degrees will have a high pressure band at 60 degrees we'll have a low pressure band and then at 90 degrees all the poles we have another high pressure band and remember this applies to both the North and to the South now that video is finished you should be able to explain the global atmospheric circulation model and you should be able to explain how circulation cells transfer heat energy around the world thank you very much for watching workbooks and test papers which integrate with these videos and online courses are available at our website backroadtutoring.com