WAEC SSCE - Geography - 2020 (Practical and Physical Geography)

(a) Five landforms found in the upper course of a river

1. V-shaped valley (deep, narrow valley cut by vertical erosion).
2. Interlocking spurs (projecting ridges the river winds around).
3. Waterfalls (and rapids where the river crosses hard rock bands).
4. Gorges (steep-sided rocky valleys, often below a retreating waterfall).
5. Potholes (circular hollows drilled into the rocky bed by swirling pebbles).

(Cascades and cataracts are also acceptable.)

(b) Alluvial fan and delta compared

Three differences

Two similarities

1. Both are depositional landforms built from river load (alluvium).
2. Both are formed where the river's velocity and carrying capacity fall sharply, and both have gentle, fan-like or spreading shapes crossed by distributaries.

(a) Five factors that affect climate

1. Latitude (distance from the equator): places near the equator receive more direct, intense insolation and are hotter than places near the poles.
2. Altitude (height above sea level): temperature falls with height (about \(6.5^{\circ}\text{C}\) per \(1000\text{ m}\)), so highlands are cooler than lowlands.
3. Distance from the sea (continentality): coastal areas have a small temperature range while interiors have hot summers and cold winters.
4. Ocean currents: warm currents raise the temperature and rainfall of adjacent coasts, while cold currents lower them.
5. Prevailing winds and relief (aspect): onshore moist winds bring rain, offshore dry winds do not, and windward slopes are wetter than leeward slopes.

(Vegetation cover and cloud cover are also acceptable.)

(b) Five characteristics of the Equatorial climate

1. High temperatures all year: mean monthly temperature is about \(27^{\circ}\text{C}\), with a very small annual range (about \(2^{\circ}\text{C}\)).
2. Heavy rainfall throughout the year: totals exceed \(2000\text{ mm}\), with no true dry season (double maxima near the equinoxes).
3. High relative humidity: often above 80 per cent, giving a hot, damp, uncomfortable feel.
4. Convectional rainfall: intense afternoon thunderstorms occur almost daily due to strong heating and rising moist air.
5. Small diurnal and seasonal contrast with heavy cloud cover: days are consistently hot, humid and cloudy with little seasonal variation.

(a) Definition of atmospheric condition

Atmospheric condition refers to the physical state of the atmosphere of a place at a given time, described by the weather elements such as temperature, rainfall, humidity, wind, pressure, cloud cover and the degree of purity or pollution of the air.

(b) Four major sources of air pollutants

1. Industrial activities/factories: smoke, soot and gases (\(\text{SO}_2\), \(\text{CO}_2\)) from manufacturing and processing plants.
2. Motor vehicles and other transport: exhaust fumes containing carbon monoxide, lead and hydrocarbons.
3. Bush burning and burning of fossil fuels: release of smoke, ash and carbon gases.
4. Gas flaring and oil operations: flares from oil fields (as in the Niger Delta) emit large volumes of gases and soot.

(Others: refuse/waste incineration, power stations, volcanic eruptions and dust.)

(c) Four effects of atmospheric pollution

1. Respiratory and other diseases: polluted air causes bronchitis, asthma, lung cancer and eye irritation.
2. Acid rain: sulphur and nitrogen oxides dissolve in rain, damaging crops, forests, buildings and water bodies.
3. Global warming and climate change: greenhouse gases such as carbon dioxide trap heat, raising temperatures and disrupting rainfall.
4. Depletion of the ozone layer: gases such as CFCs thin the ozone shield, increasing harmful ultraviolet radiation.

(Also: reduced visibility/smog, poor plant growth and lower agricultural yields.)