Practice NAB questions
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The differing albedos across the earth’s
surface will have an impact on the amount of
solar radiation reflected by the earth’s surface.
Over the tropical zones there is more
vegetation, particularly at the equator where
there is dense forest, this tends to absorb
radiation rather than reflect. At the poles there
is more radiation reflected due to the snow and
ice which is white is colour. The oceans and
seas also reflect a lot of radiation from the
earth’s surface.
Practice NAB questions
•
Include a well annotated diagram. More solar radiation is
received at the tropics than the poles due to a number of reasons;
the amount of surface area heated at the tropics is smaller than at
the poles allowing more intense heating to take place. The
amount of atmosphere which the sun’s rays have to pass through
is greater at the poles than at the equator, so more radiation is
reflected by clouds, dust and gases. The differing albedos can
have an effect, dense forest at the equator absorbs more
insolation than it reflects, whereas the ice and snow at the poles
reflects more solar energy. The angle at which the sun’s rays
strike the earth’s surface varies with the sun striking at a right
angle at the equator and at a shallower more acute angle at the
poles. Finally the equator receives two solar maxima’s a year
whereas there is only one in the N+S hemispheres.
Practice NAB questions
(c) The diagram shows the movement of winds on the earth surface. Winds
are created when there are differences in air pressure. Winds blow from
areas of high pressure to areas of low pressure. On the diagram it can be
seen that polar easterlies blow from the high pressure zone at 90 degrees
to the low pressure zone at 60 degrees. Trade winds are found blowing
from the sub-tropical high pressure zone at 30 degrees towards the equator.
Mid- latitude westerlies blow from 30-60 degrees.
The diagram also shows the circulation cells;
The Hadley cell found between 0-30 degrees N&S of the equator, air is heated
at the equator rises and expands polewards, coriolis deflected the winds
and they descend at 30 degrees forming a high pressure zone. Some of
the air returns towards the equator as the trade winds. Meanwhile there is a
deficit of solar energy at the poles cold air descends and the cold air is
blown towards the equator as the polar easterlies. At 60 degrees the warm
mid latitude westerlies which are transferring warn air from the tropics meet
the cold polar easterlies at 60 degrees creating a polar front, where warm
air is exchanged for cold air.