Selection of Atmosphere Sample answers
Q: Explain fully the ways in which the circulation cells in the atmosphere help to redistribute energy. (10 marks)
Heat is transferred throughout the globe by three major cells  , the Hadley, Ferrel & Polar cells  . At the equator air is warmed up by the overhead sun  causing it to rise  , as it does so it eventually starts to cool causing rainfall  , and then falls back down  to earth at 30° N or S of the equator  . This moves warmer air away from the equator  polewards and is called the Hadley cell. At the poles cold air falls  to the earth’s surface and then moves towards the equator  . At latitude 60° N or S the air warms up and rises  , cooling to give rainfall  . Some of it circulates back to the poles  , whilst some drops to latitude 30° N or S  moving cooler air to these latitudes  . The air falling at latitude 30° N or S is moved by the Ferrel cell and the air circulating between 90° N or S and 60° N or S is moved by the Polar cell  .
Q: For either the Pacific or the Atlantic Ocean, explain how the ocean currents operate to maintain the energy balance (8 marks)
At the equator water warmed by the overhead sun  starts to move in a north westerly direction towards the Caribbean  by the North equatorial current  , transferring heat to seas in higher latitudes  . The current hits the North American continent and is deflected in a north easterly  direction towards Europe forming the gulf stream  current. Again higher latitudes receive warmer water  . Cooler water from the Arctic & Northern Canada  mix with the gulf stream cooling it  and is then sent southwards to Africa  as the gulf stream is deflected as it hits Europe  . Africa receives this cooler current called the canaries current  , which is deflected by Africa towards the equator  , where it is heated up by the sun  . The circulatory nature of these currents is called a gyre  and is clockwise in the Northern hemisphere  . They can be assisted in their movement by the corriolis affect  , the spinning of the earth. The prevailing westerlies and trade winds  can also help to the gyre to circulate.
Credit can be given for convection currents; recognition that 25% of the earths heat budget is transferred by the oceans.

Energy gains and losses
The two main features of the earth's energy balance are that:
 there is a net gain of solar energy in the tropical latitudes and a net loss
 towards the poles tropical latitudes receive more of the sun's energy than polar regions
Input into the global heat budget comes in the form of short-wave solar energy. This is called insolation.
Only 51% of this insolation reaches and is absorbed by the earth's surface. The rest is absorbed by water vapour, dust and clouds, or is reflected by the earth's surface and scattered by particles in the air (the albedo effect ). The atmosphere is largely heated from below, by long-wave terrestrial radiation from the earth's surface.
Latitude and energy balance
You can see that there is a surplus of energy between 35N and 35S. In this region, incoming insolation exceeds outgoing radiation. There's an energy deficit between 35N and the north pole, and between 35S and the south pole. Here the outgoing radiation exceeds incoming insolation.
Insolation rises sharply from 50 joules at the poles to 275 joules at the equator.
Terrestrial radiation varies less, from 120 joules at the poles to 200 joules at the equator.
Energy is transferred from the low-latitude energy surplus areas to the high-latitude energy deficit areas by atmospheric circulation. If there was no atmospheric

circulation, the low latitudes would get hotter and hotter and the high latitudes colder and colder.
Why do tropical latitudes get more heat than polar latitudes?
In tropical latitudes:
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 the sun's rays are more concentrated, as the noonday sun is high in the sky throughout the year the sun's rays have less atmosphere to pass through, so less energy is lost through absorption and reflection by the atmosphere in tropical rainforest areas, dense vegetation absorbs radiation giving a low relative albedo effect.
At high latitudes:
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 the sun's angle is much lower, so the rays of energy are spread out over a much larger area and are therefore less intense because of the earth's curvature, our planet's surface slopes further away from the sun, making heating less intense
 in polar regions, snow and ice cover reflect much more of the solar radiation, giving a high albedo effect
Possible answer
The sun's rays are more concentrated in tropical latitudes. This is shown by line AB being shorter than line DE. At high latitudes, the sun's angle is lower and rays of energy are spread out over a larger area. This is shown by line DE. In tropical latitudes the sun's rays have less atmosphere to pass through so less energy is lost passing through the atmosphere. The albedo effect also differs between the tropics and the poles. Reflection is much greater in polar latitudes because of the presence of snow and ice.

How is heat transferred from the tropical latitudes to the polar latitudes?
Heat is transferred by a series of convection cells. Rising air at the equator drives the Hadley Cell. Sinking air at the poles drive the polar cell. The ferrel cell is driven by the other two cells. This atmospheric circulation cools the equator by dragging in cooler air. It warms the poles by dragging in warmer air. It maintains the earth’s energy balance