Flash Player 9 (or above) is needed to view presentations.
We have detected that you do not have it on your computer. To install it, go here.

Like this presentation? Why not share!

Energy Balance






Total Views
Views on SlideShare
Embed Views



4 Embeds 337

http://eperalta.org 151
http://online.peralta.edu 149
http://www.eperalta.org 36
http://www.slideshare.net 1



Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
Post Comment
Edit your comment

Energy Balance Energy Balance Presentation Transcript

  • Energy and the Atmosphere
  • Overview
    • Insolation-Atmosphere Interactions
      • Scattering
      • Refraction
      • Reflection
      • Absorption
      • Heat Transfer
        • Conduction
        • Convection
        • Advection
      • Greenhouse Effect
    • Energy Balances
      • Atmospheric Radiation Balance
      • Surface Energy Budget
  • Energy Budget
    • Open Systems model: Shortwave Energy in, Longwave Energy out
    • The Energy Budget describes what happens to insolation after it passes the thermopause, passes through the atmosphere and reaches the surface.
      • Atmospheric effects
      • Ground effects
  • Insolation-Atmosphere Interaction
    • Refers to what happens after the intercepted solar radiation enters the atmosphere
      • Transmission
      • Both short and long wave radiation
    • As light encounters gas molecules and particulates in the atmosphere, the pathway that the light follows changes
      • Diffusion (scattering)
      • Refraction
      • Reflection
      • Absorption
  • Diffusion
    • The Sun’s rays are essentially parallel as they reach the Earth’s surface.
    • As they encounter various particles in the atmosphere, some light rays are bounced in all the different directions.
      • Diffusion, or scattering
      • Some light scattered back into space (7%)
      • Some light scattered to the Earth’s surface (20%)
    • Diffusion increases as sun angle decreases
  • Incoming rays Scattered rays Gaseous medium
  • Refraction
    • Occurs when light passes from one medium to another
      • From air to water droplets
      • From air masses of varying temperature and density
    • Light ray slows and changes direction
      • Short wavelengths are refracted more than long wavelengths
        • Breaks light into a spectrum; rainbows
      • Convection currents in the air (rising hot air) cause refraction, creating a shimmery distortion
        • mirages
  • Medium 1 Medium 2 Incoming rays Refracted rays
  • Reflection
    • Light that bounces off a surface
    • Albedo refers to the amount of light reflected back to space
      • 31% of incoming sunlight is reflected
        • 21% by clouds
        • 7% by diffuse scattering
        • 3% by the Earth’s surface
      • Mainly short wave radiation
    • Factors that increase albedo
      • Light color
      • Smooth surfaces
      • Low sun angle
  • Medium 1 Medium 2 Incoming rays Reflected rays
  • Absorption
    • Light that is not part of Earth’s albedo
    • Light that is assimilated by matter (69%)
      • Ozone in the stratosphere (3%)
      • Clouds (3%)
      • Atmospheric gases and dust (18%)
      • Earth’s surface (45%)
        • Including photosynthesis
    • Causes the matter to increase in temperature
      • short wave energy is converted to long wave (infrared)
        • including respiration
    • Absorbed heat energy can be transferred in the atmosphere
      • Heat energy flows from high to low heat
      • conduction
        • transfer of heat energy between two objects through physical contact
        • Phase changes: Latent heat
      • convection
        • occurs in mobile media (liquids, gases)
        • currents: molecules near heat source rise (and cool) while cooler molecules fall (and become heated)
      • advection
        • similar to convection, but occurs horizontally
      • radiation
        • heat transmitted as infrared radiation
  • Greenhouse Effect
    • Clouds
      • Are variable in cover
      • Exert tremendous influence on energy budget
        • Increase albedo (albedo forcing)
        • Increase greenhouse warming (greenhouse forcing)
          • Certain gases in clouds absorb and reradiate infrared radiation
            • Carbon dioxide, water vapor, methane
          • Creates an insulating effect
    • Different cloud types affect the greenhouse effect differently
      • High thin clouds allow more diffuse light through, causing more heat to be trapped (net greenhouse forcing)
      • Low thick clouds reflect more light out, causing less heat to be trapped (net albedo forcing)
    • The greenhouse effect has been identified as the main cause of global warming
  • Energy Balances
    • Atmospheric radiation balance
    • Surface radiation balance
    • Surface Radiation Balance
      • Refers to 45% of insolation that reaches the Earth’s surface
      • Daily Pattern
        • Insolation peaks at noon
          • varies seasonally, with maximum on the summer solstice
        • Absorbing the insolation heats the ground, which in turn heats the air
          • Maximum air temperature reached between 3-4 pm
          • Minimum air temperature reached around dawn