Rain

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Rain falling
Rain falling

Rain is droplets of water falling down from clouds in the sky. Droplets of water with a diameter larger than 0.5 mm are rain. Those with a diameter of about 0.2-0.5 mm are drizzle.

Rain is part of the water cycle. Rain is a form of precipitation.

[edit] Types of rain

[edit] Convection rain

Convection rain is commonly found in hot wet places of the world. Sometimes it is also found in tropical deserts and inland areas during summer, when temperatures are high. During daytime, the sun makes the ground very hot. Air near the grounds surface is heated by conduction. It then grows bigger and goes up, forming strong upwards air currents. When temperature of the rising air falls to dew point, water vapour shrinks into thick cloud and forms convection rain.

[edit] Relief rain

Relief rain usually occurs along coastal areas where a line of hills runs along to the coast. When wet onshore winds from the sea meet a mountain barrier, it is forced to rise along the slope and cools. When the air temperature falls to its dew point, water vapour condenses to form clouds. When the clouds can no longer hold the water droplets, relief rain begins to fall on the windward slope of the mountain. On the leeward slope, air sinks, it is warmed and further dried by compression. Therefore, the leeward slope is known as the rain shadow.

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