Atmosphere Past Paper Question Model Answer – 2006 Q. 1
a)
b) With the aid of an annotated diagram, explain why there is a surplus of solar energy in the
tropical latitudes and a deficit of solar energy towards the poles.
(10)
There is a surplus of energy in the tropical latitudes because incoming solar radiation exceeds
outgoing terrestrial radiation. (1) There is a deficit towards the poles because outgoing
terrestrial radiation exceeds incoming solar radiation. (1)
Due to the curvature of the earth the sun’s rays
are spread over a larger surface area. (1)
Therefore the energy is less concentrated than at
lower latitudes creating a deficit at the poles. (1)
Again, due to the curvature of the earth the sun’s
rays of insolation must pass through a greater
area of atmosphere at the poles than at the
equator (X is greater than Y in the diagram). (1)
Therefore the energy is less concentrated towards
the poles. (1) As there is more atmosphere to
pass through at higher latitudes there may also be
more clouds, water vapour, dust and gases
increasing reflection and reducing energy. (1)
(1)
The poles are covered in large white ice-sheets which enhances the albedo effect (the total
percentage of reflection of solar energy from the atmosphere). (1) Whereas large parts of
tropical latitudes are covered in dark dense forest which will absorb solar energy and add to
the surplus. (1)
Due to the Earth tilting on its axis (between 23˚N + S) the poles are plunged into
darkness for six months of the year. (1) During these times they receive little to no solar
energy. (1) Tropical latitudes have the sun overhead throughout the year (1) which adds the
energy surplus in these latitudes. (1)
14 marks!