ATMOSPHERE

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ATMOSPHERE

• MOISTURE IN THE ATMOSPHERE

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MOISTURE IN THE ATMOSPHERE

• Humidity vs. Relative Humidity
• Atmosphere contains water vapor
• Humidity amount of water vapor in the air
• Humidity is to blame for that muggy, steam-room
  feeling you experience on certain summer days

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MOISTURE IN THE ATMOSPHERE

• Humidity vs. Relative Humidity
• Relative Humidity the ratio of water vapor in a
  volume of air relative to how much water vapor
  that volume of air is capable of holding.
• Expressed as a percentage ()
• Warm air can hold more moisture than cool air
• A reading of 100 means that the air is totally
  saturated with water vapor and cannot hold any
  more, creating the possibility of rain.

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MOISTURE IN THE ATMOSPHERE

• Cloud Formation
• Clouds form when warm, moist air rises, expands,
  and cools in convection current
• When millions of droplets of water collect, a
  cloud forms

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MOISTURE IN THE ATMOSPHERE

• Cloud formation
• Orographic lifting
• Wind encounters a mountain and has no place to go
  but up
• This rising causes the air to expand and cool
  creating a cloud
• Also, if a warm mass of air collides with a
  cooler mass of air, the warm air is forced above
  the cool air creating clouds

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MOISTURE IN THE ATMOSPHERE

• Types of Clouds
• Background
• Air rises
• Water Vapor condenses into droplets of liquid
  water
• If density great enough, droplets become visible
• Classification
• Grouped by altitude of formation and shape
• Low clouds (STRATO) below 2000 m
• Middle clouds (ALTO) between 2000 m and 6000 m
• High clouds (CIRRO) above 6000 m

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MOISTURE IN THE ATMOSPHERE

• Types of Clouds
• Low Clouds (STRATO)
• Radiation causes surface to become warmer than
  surrounding air
• Temperature rises air expands
• Air rises and begins to cool
• Water vapor condenses into water droplets
  creating a visible cloud

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MOISTURE IN THE ATMOSPHERE

• Types of Clouds
• Low Clouds (STRATO)
• Cumulus cloud if air does not stay warmer than
  surrounding air, cumulus cloud forms
• Flat cloud and spread horizontally
• Puffy, lumpy looking clouds
• Cumulus Pile or heap

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MOISTURE IN THE ATMOSPHERE

• Types of Clouds
• Low Clouds (STRATO)
• Nimbus cloud
• Low, gray rain clouds
• Nimbus cloud

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MOISTURE IN THE ATMOSPHERE

• Types of Clouds
• Low Clouds (STRATO)
• Stratus if fog lifts away from Earths surface,
  stratus clouds form
• Forms at heights below 2000m
• Layered cloud that covers much or all of sky in
  given area
• Featureless sheets of clouds
• Stratus layer

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MOISTURE IN THE ATMOSPHERE

• Types of Clouds
• Middle Clouds (ALTO)
• Either altocumulus or altostratus
• Forms between 2000 m and 6000 m
• Can be mixture of liquid and ice crystals
• Usually layered
• Altocumulus resemble white fish scales
• Altostratus are dark but thin veils of clouds
• Can produce mild precipitation

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MOISTURE IN THE ATMOSPHERE

• Types of Clouds
• High Clouds (CIRRO)
• Form above heights of 6000 m
• Made up of ice crystals due to low temperatures
• Cirrus clouds appear wispy and stringy
• Cirrus hair
• Cirrostratus forms as a continuous layer that
  sometimes covers sky
• Can vary in thickness from being almost
  transparent to being able to block out Sun or Moon

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MOISTURE IN THE ATMOSPHERE

• Types of Clouds
• Vertical Development Clouds
• If air that makes up cumulus cloud is unstable,
  cloud will be warmer than surface or surrounding
  air and will grow
• As it rises, water vapor condenses
• Air receives additional warmth
• Cumulonimbus anvil shaped
• Produces torrential rains and strong winds
• Associated with thunderstorms

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MOISTURE IN THE ATMOSPHERE

• Precipitation
• Cloud droplets collide and join together
• Coalescence the process in which a larger
  droplet forms from collision of cloud droplets
• If droplet becomes too heavy to be held in the
  air, gravity pulls the droplet down as
  precipitation.
• Precipitation all forms of water both liquid
  and solid that fall from clouds

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MOISTURE IN THE ATMOSPHERE

• How do we get snow?
• If precipitation forms at cold temperatures, it
  takes the form of snow
• How do we get hailstone or sleet?
• Convective currents carry droplets up and down
  through freezing and nonfreezing air