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clouds 
Fine droplets of water or ice crystal suspended in the atmosphere; the World Meteorological Organization classifies them according to 10 types.
middle clouds
Clouds at an altitude of 2,000 to 6,000 meters and composed of water droplets and ice crystals.
altostratus
Gray sheet that can completely cover the sky but allows the Sun to be seen without a halo phenomenon; it can trigger heavy precipitation.
altocumulus
Cloud composed of large white or gray flecks that sometimes form parallel layers; it foreshadows the arrival of a depression.
