All About Clouds

• Clouds are collections of ice crystals and water vapor in the atmosphere.
• A cloud's structure, shape, and appearance varies based on water content and environmental factors.
• Cloud properties differ, with formation times ranging from minutes to hours.
• Cloud sizes vary and some clouds can weigh over a million pounds.

Cloud Formation

• Cloud formation begins with water evaporation from the Earth's surface into water vapor.
• Water vapor rises and cools with increased atmospheric elevation.
• Cooling causes water droplets to condense via contact with airborne particulates.
• Collections of water droplets group together, forming clouds.
• A shapes, colors, and atmospheric position identifies a cloud's type

Cloud Categories by Altitude

• Low clouds: surface to 7,000 feet
• Medium clouds: 7,000 to 17,000 feet
• High clouds: 17,000 to 35,000 feet
• Vertical clouds: span multiple atmospheric heights

Low Clouds

• Low clouds occur below 7,000 feet and can even be found on the Earth's surface.
• Fog is a low-hanging cloud.
• Types of low clouds:
  • Cumulus
  • Stratus
  • Stratocumulus
• Cumulus clouds:
  • White, irregular clouds that develop on clear days
  • Uneven edges and flat bottoms
  • Large cumulus clouds can produce rain and thunderstorms
  • Often called "fair weather clouds" due to association with pleasant weather
• Stratus clouds:
  • Grey and appear as a sheet across the sky
  • May form from rising fog via warm, uplifting wind
  • Thick stratus clouds can develop light showers or snow
• Stratocumulus clouds:
  • Hybrid of cumulus and stratus clouds
  • Look like sheets of cumulus clouds smeared across the sky
  • Often grey and form when cumulus clouds split apart

Middle Clouds

• Middle clouds are found between 7,000 and 17,000 feet.
• Types of middle clouds:
  • Altocumulus
  • Altostratus
  • Nimbostratus
• Altocumulus clouds:
  • Small white or gray clouds that dot the sky
  • More or less have definitive edges
  • Can produce light showers and sometimes thunderstorms
  • Form via convection, where rising hot air cools rapidly
• Altostratus clouds:
  • Appear sheet-like without well-defined edges
  • May occasionally produce rain, snow, or hail
• Nimbostratus clouds:
  • Dark grey and are thick enough to hide the sun
  • Cover most of the sky and create dark, dreary days

High Clouds

• High clouds are found between 17,000 and 35,000 feet.
• Types of high clouds:
  • Cirrus
  • Cirrocumulus
  • Cirrostratus
• Cirrus clouds:
  • White and composed of ice
  • Found at roughly 20,000 feet
  • Appear like wispy collections of hair
• Cirrocumulus clouds:
  • Appear like sheets of white clouds cut into small, individual rows
• Cirrostratus clouds:
  • Sheets of cloud that expand across much of the sky
  • Largely transparent and may cause a halo around the sun

Vertical Clouds

• Cumulonimbus clouds:
  • Tall and span across elevational boundaries
  • May appear as large, boding clouds with an anvil-shaped top
  • Generally form before thunderstorms

Clouds consist of ice crystals and water vapor, varying in structure and shape due to water content and environment. Cloud formation starts with water evaporating from the Earth's surface, rising, and cooling, leading to condensation around airborne particles. Classifications are based on altitude.