HIGHER GEOGRAPHY – ATMOSPHERE HOMEWORK 3
QUESTIONS (2005 SPECIMEN AND ACTUAL PAPER)
1. Describe the origin, nature and weather characteristics of Tropical
Maritime and Tropical Continental air masses.
8 marks
2. Using the maps and graphs, describe and explain the pattern of annual
rainfall in both the north and south of Nigeria.
10 marks
3. Explain the human factors which may have led to the changes in global mean
temperatures shown in the diagram
8 marks
26 marks
GENERAL POINTS
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Evidence that notes are being well used
Most answers actually answering the question
Be careful that you mention the air masses in question 2
You do not get marks in question 2 for describing the weather characteristics
of the two air masses – this was credited in question one
You must mention the ITCZ in question 2 to score more than 6 or 7/10
In the global warming question you are asked to explain. You should try to
bring in at least 4 causes / gases
MODEL ANSWER:
Question 1
The Tropical Maritime air mass originates over the Atlantic Ocean in the Tropical
latitudes. The nature is warm, moist and unstable. Associated weather characteristics of
this air mass are very hot weather and high rainfall. This air mass is very humid (65 – 82%
relative humidity).
The Tropical Continental air mass originates over the Sahara desert, a large land mass in
the tropical latitudes. This results in the development of a warm, dry and stable air mass.
Very warm conditions are associated with dry weather in the winter and extremely hot and
dry summers. Humidity remains low at about 10 – 17%.
MODEL ANSWER
Question 2
In the North of Nigeria there is a one-peak rainfall system. The rainy season runs from
May through September. In the summer the ITCZ moves North and this brings rain to
northern parts of Nigeria. By January the ITCZ has migrates south and the cT air mass is
dominant in the North. This air mass leads to a period without rain running from November
through to April.
In the South there is a two-peak system. Rain is found throughout the year. The two peaks
are caused by the ITCZ and the associated belt of rain which moves with it. This causes
above average rainfall in May to June as it tracks North and then again in September to
October when the ITCZ returns South.
Question 3
There are a number of greenhouse gases which act to trap heat in the atmosphere and
have contributed to global warming over the last century.
Carbon dioxide levels have increased in the main die to the burning of fossil fuels. This has
occurred as car ownership has exploded in the last 50 years. The burning of coal and gas in
power stations is also responsible. Deforestation reduces the capacity of trees to absorb
carbon dioxide and turn it into oxygen. Burning of trees also releases stored carbon
dioxide.
CFCs found in aerosols, refrigerators, air-conditioning units and polystyrene packaging also
release gases into the atmosphere which trap more of the sun’s radiation in the
atmosphere thus warming the planet.
The explosion in the world’s population is also linked to rises in temperatures. Food
production has had to increase to meet demand. As a result methane is being released into
the atmosphere from paddie fields and flatulent livestock. Methane is a greenhouse gas.
Nitrous oxides are the final major greenhouse gas. They are more abundant in the
atmosphere due to vehicle emissions (rising car ownership) and power stations.