Theory question 203
Weather(a) (i) Name any two types of rainfall. (ii) State the region where each of the two types of rainfall named in (a)(i) above is prevalent. (b) Write explanatory notes on the formation of the two types of rainfall named in (a)(i) above.
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(a)(i) Convectional, relief (orographic), frontal (cyclonic).
(ii) Convectional: equatorial regions and tropics in summer (e.g. Congo basin, southern Nigeria). Relief: windward sides of mountains near coasts (Cameroon Mountain, Fouta Djallon, western Europe). Frontal/cyclonic: temperate mid-latitudes (Western Europe, North America).
(b) Convectional: strong heating of the ground; warm moist air rises in convection currents; it expands and cools to dew point; condensation forms cumulonimbus clouds; heavy afternoon showers with thunder and lightning.
Relief: moist wind from the sea is forced up a mountain; it cools and condenses on the windward side giving heavy rain; air descends the leeward side, warms and is dry (rain shadow).
Frontal: warm air meets cold air at a front; the lighter warm air rises over the cold air; it cools and condenses, giving widespread steady rain.
Diagrams help but are not required.