ENERGY CH 2

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ENERGY (CH 2)
The ability to do Work
UNITS Joule (J)
POWER The rate at which energy is released,
transferred, or received
UNITS Joule/second (J/s)
Types of Energy
Kinetic Energy Potential Energy
Look at figure 2-1 p.32
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ENERGY
Transfer mechanisms
Conduction Convection Radiation
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Heat transfer in the atmosphere

• 1. Conductiontransfer of heat from molecule to
  molecule.
• Works best in solid objects (molecules locked
  together)
• Air is a poor conductor.

Sun warms the Earths surface and the heat is
conducted to a small layer of air Above the
surface. (Think of heat waves off of blacktop)
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• 2. Convectiontransfer of heat by the mass
  movement of a fluid (currents).
• Air near surface heats, becomes less dense, and
  rises. Cooler air above is brought down to the
  surface.
• Most of the heating in the lower atmosphere
  comes from earths the surface (from below)

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Rising Warm Air--Thermals
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3. Radiation

• Electromagnetic radiation has a dual nature
• It moves through the vacuum of space as a wave
• It interacts with matter like a particle
• Moves at the speed of light--186,000 miles/sec
• Wavelength measured in micrometers (one millionth
  of a meter µm)
• Longer wavelengths carry less energy

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RADIATION
Quantity and Quality
Quality the type of radiation This is
measured by its wavelength
Quantity amount of energy transferred.
measured by its amplitude
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RADIATION-Type
FIG 2-6 p. 36
Shortwave carries more energy Than longwave
radiation

• Infrared radiation (IR)
• emitted by The Earth is
• considered Longwave
• (thinkcan you
• Get a sunburn at night from
• Heat emitted by earth?)
• Ultraviolet (UV) emitted by
• The sun is considered
• Shortwave
• Visible emitted by both the
• Sun and the Earthwe see
• Colors because of this

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RADIATION
Intensity and Wavelengths of emitted radiation

• 1. Sun emits energy with shorter
• Wavelengths than Earth
• Sun is hotter than Earth and
• Therefore radiates more energy.

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Infrared light is used in meteorology to view
weather From space white clouds are cold, dark
areas are warm IR satellite image
RADIATION
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FLIR (forward looking IR)(Time to change that
flight suit)
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Atmospheric Influences on Insolation
As solar radiation enters the atmosphere, not all
of it makes it to Earths Surfacethe following
are the fates of solar radiation

• Absorption
• Reflection Scattering
• Transmission

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Absorption
Atmospheric gases, particulates, and droplets all
reduce the intensity of solar Radiation
EFFECTS

• The absorber gains energy and warms
• The amount of energy delivered to the surface is
  reduced

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Reflection
Reflection radiation is redirected away from
the surface without being absorbed Albedo The
percentage of visible light reflected

• TWO TYPES
• Specular Reflection
• Diffuse Reflection

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Scattering
Disperse radiation in different directions
3 TYPES

• Rayleigh
• Mie
• Nonselective

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Rayleigh Scattering
Disperse radiation both forward and backward

• Leads to blue skies on a clear day
• The redness of sunsets and sunrises

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Mie Scattering
Disperse radiation predominately forward

• Effectively scatters all wavelengths therefore
  sky looks gray
• Causes sunrises to be redder

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Nonselective Scattering
Each wavelength is being refracted a different
amount
Creates Rainbows and Iridescence in clouds
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Transmission
When solar radiation enters the atmosphere only a
fraction Makes it to the surface
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Transmission The Fate of Solar Radiation

• 100 units available at the top of the atmosphere
• Atmosphere absorbs 25 units
• 7 units are UV radiation absorbed by ozone
• Remainder is IR radiation absorbed by gases
• Clouds reflect 19 units back to space
• Gases and aerosols scatter 6 units back to space
• 50 units reach the surface
• 5 units scattered back to space

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Earths Energy Balance
Outgoing radiation 30 Incoming radiation70
100
Planetary albedo196530!!!! Think about
what would happen if this were higher or lower
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Earths Energy Balance
Outgoing radiation 30 Incoming radiation70
Incoming gt Outgoing Temperature rises Ex. equator
Outgoing gt Incoming Temperature decreases Ex.
poles
The primary principle of the energy budget is
that Earth would like Incoming radiation to
equal outgoing radiation, but since it doesnt
weather Happens to balance the surplus of heat at
the equator and the deficit at the poles