Anonymous
Anonymous asked in Science & MathematicsWeather · 8 years ago

Why do clouds have flat bottoms?

Was just watching the sky today, and I noticed that pretty much every cloud has a flat bottom. I kinda would expect them to be poofy, but I don't know why they would have flat bottoms.

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  • 8 years ago
    Favorite Answer

    Clouds are formed by rising air. As the air rises it cools. If it cools enough the air reaches its dew point, the temperature at which condensation begins. Thus when the air rises to a specific level, the water vapor begins condensing out to form the cloud material, which continues to form as the air continues to rise. The flat bottom indicates that level of condensation.

    Source(s): I'm a meteorologist
  • 8 years ago

    Answer 1

    Many clouds are flat on the bottom because as the air rises from the surface it cools, and at the saturation temperature it starts to condense, which is where the clouds start. Since the whole column is starting at the same conditions and going through the same process, it all condenses at the same height.

    Answer 2

    Clouds are formed when the temperature of the atmosphere reaches the condensation point (this is when it turns to water vapor). When this happens, the water vapor sticks to dust particles in the air and becomes visible. The temperature of the atmosphere usually changes(gets colder) as you go up, so only at a certain point can the water vapor droplets form. When you see the flat bottoms of clouds, you see where this point begins - this is the beginning of the proper temperature for water vapor to form.

  • TQ
    Lv 7
    8 years ago

    Clouds described as 'poofy' and having 'flat bottoms' sure do sound like fair-weather cumulus.

    - Fair weather cumulus are created by thermals

    - Thermals are columns of warm air rising from the earth's surface in response to incoming radiation from the sun.

    - When water vapor inside the rising thermal cools to its dew point...it condenses...and a 'poofy' cumulus cloud forms.

    Cumulus clouds have flat bottoms b/c the height above ground is locally the same where the thermal's water vapor condenses.

    Think of it like a ceiling...where once the rising air reaches it...it's cloud-time!

    Source(s): Meteorologist. 41 years experience.
  • Mawia
    Lv 7
    8 years ago

    They appear flat from the ground, but to a glider pilot soaring underneath them, they are usually slightly concave - caused by the force of the rising air underneath pushing upward.

    Source(s): wife of a soaring instructor
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  • 8 years ago

    They dont!

    Look again...different types of clouds have different bottoms. Tornado clouds have humpy (to be polite) bottoms. Thy are Mammatus Nimbus clouds.

    EDIT - to all the experts ...check out my link to see these "flat bottoms"

    http://images.search.yahoo.com/search/images?_adv_...

    • conundrum6 years agoReport

      No one said ALL clouds have flat bottoms... the question was why do clouds appear to have flat bottoms...? .. and some indeed do...you have taken some nice pictures tho.

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