Theory question 204
WeatherWith the aid of diagrams, describe the formation of each of the following: (a) Orographic rainfall (b) Convectional rainfall
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(a) Orographic (relief) rainfall: moist wind from the sea meets a mountain barrier and is forced to rise; it cools adiabatically, reaches dew point and condenses to form clouds; heavy rain falls on the windward side; air descends on the leeward side, warms and gives little rain (rain shadow), e.g. Cameroon Highlands, Jos Plateau.
(b) Convectional rainfall: intense heating of the ground warms the air above; the warm moist air expands and rises in strong convection currents; it cools and condenses to form towering cumulonimbus clouds; heavy afternoon showers with thunder and lightning follow; common in equatorial regions.
Label wind direction, rising air, condensation level and rain on each diagram.