Climate

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Climate

• Continued

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Layers of the Atmosphere

• The atmosphere has 4 distinct layers, each with a
  particular set of properties.
• Layers are
• divided by temperature patterns
• vary in thickness
• are separated by interfaces with names ending in
  pause.

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Layers of the Atmosphere

• The 4 layers of the atmosphere are
• Thermosphere
• mesopause
• Mesosphere
• stratopause
• Stratosphere
• tropopause
• Troposphere

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Troposphere

• Closest to the surface of the Earth
• Temperature drops as you rise (6.4oC/km)
• Composition is 78 nitrogen, 20 oxygen, 2 other
  gases (Ar,CO2,Ne,He)
• Contains most of the dust and water vapor
• Most weather occurs in this layer

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Tropopause
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Stratosphere

• Layer above troposphere
• Temperature rises as you rise
• Very little weather

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Stratopause
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Mesosphere

• Layer above the stratosphere
• Temperature drops (to -90oC) as you rise

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Mesosphere Clouds
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Mesopause

• Located where the temperature stops falling in
  the mesosphere.

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Thermosphere

• The outer, upper layer of the atmosphere
• Temperatures rise to 1000oC as you rise
• Very little matter in this layer
• High temperatures due to x-rays and UV

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Atmosphere Affects Insolation

• Absorption the stratosphere absorbs most of the
  ultraviolet radiation while carbon dioxide and
  water vapor in the troposphere absorb most of the
  infrared radiation.
• Reflection clouds reflect approximately 25 of
  incoming insolation.

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Atmosphere Affects Insolation

• Scattering aerosols (water droplets, ice
  crystals, pollutants and dust) in the atmosphere
  cause random reflection of insolation. This
  scattering of insolation increases as levels of
  aerosols increases. As scattering increases
  insolation to the surface decreases.
• Ex volcanic eruptions increase aerosols and
  greatly reduce insolation to the surface.

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Atmosphere Affects Insolation

• Energy conversion some energy is converted to
  potential energy (latent heat) by the evaporation
  of water and the melting of ice and snow. This
  reduces the amount of energy available to heat an
  area and also increases the amount of water vapor
  in the air which also reduces the insolation
  available making for lower temperatures.
• Energy is also radiated back into space in the
  form of heat (infrared).

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Surfaces

• Land surfaces heat up and cool down more rapidly
  than water surfaces.
• Since good absorbers are also good radiators, the
  land radiates heat to the air above more rapidly
  than water does.
• So air above the land heats and cools more
  quickly than air over water.

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Terrestrial Radiation

• Terrestrial radiation is electromagnetic energy
  given off by the Earths surface.
• This is in the form of infrared radiation.

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The Greenhouse Effect

• The process that allows short-wave energy to be
  transmitted through the atmosphere, but which
  reflects and captures reradiated long wave
  infrared energy is known as the greenhouse effect.

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Radiative Balance vs. Time

• Radiative balance occurs when the incoming energy
  equals the outgoing energy.
• Over long-term periods the Earth seems to be in
  radiative balance
• Over short-term periods the Earth does not seem
  to be in radiative balance.

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The Water Budget

• Evapotranspiration refers to all the moisture
  released into the atmosphere by both evaporation
  and transpiration.
• A water budget is a monthly account of what
  happens to all the water in a particular location
  over the course of a year.

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Water Budget Income and Expenses

• Income in a water budget is the amount of
  precipitation.
• Expenses in a water budget is the potential
  evapotranspiration.
• Potential evapotranspiration is the amount of
  water that would evaporate or transpire if the
  water were available.
• Therefore potential evapotranspiration is highest
  in the summer (when it is hottest), lowest in
  winter (when it is coldest).
• Large vegetated areas give off more
  evapotranspiration.

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Factors Affecting Water Budgets

• Climate affects a water budget since
  evapotranspiration rates are largely dependent
  upon the sun, the factors determining climate
  (temperature and humidity) also affect water
  budgets.
• Arid climate total annual precipitation is less
  than potential evapotranspiration.
• Humid climate total precipitation is more than
  potential evapotranspiration.

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Stream Discharge

• Stream discharge is the amount of water passing a
  given point in a stream during a given time.
• Areas with surplus moisture usually have large
  amounts of runoff into streams.
• Greater amounts of runoff means greater stream
  discharge.
• During dry, or deficit, periods when runoff
  diminishes, streams take water from the ground
  water supply this is called base flow.