Theory question 206
WeatherWrite explanatory notes on the following: (a) formation of clouds; (b) relief rainfall.
Show the model answer
Model answer
(a) Moist air rises (by heating, over mountains, or along fronts); it expands and cools adiabatically; when it cools to dew point it becomes saturated; water vapour condenses on tiny particles (condensation nuclei: dust, salt, smoke) into droplets or ice crystals; masses of these form clouds (cirrus, cumulus, stratus, nimbus).
(b) Moist wind from the sea meets a mountain barrier and is forced to rise; it cools, condenses and forms clouds; heavy rain falls on the windward side; the air descends the leeward side, warms and becomes dry, giving a rain shadow; e.g. Cameroon Mountain, Jos Plateau. Diagram helpful.
Explanation
A diagram makes relief rainfall clear.