When the collected water becomes heavy enough the water droplet falls to the earth as rain.
水气凝结到一定程度就形成了小水滴,其重量足以使它落到地上,即为雨.
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Double arcs happen when light is reflected more than once in an atmospheric water droplet.
双拱形彩虹的出现是当光线被折射超过一度存于大气层的水微滴.
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