Energy, Radiation, Insolation, and Energy Transfer

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Energy, Radiation, Insolation, and Energy Transfer
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Types of Energy

• Potential energy (Gravitational)
• Kinetic energy
• Thermal energy
• Radiation (Electromagnetic)

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Solar Radiation Sun to Earth

• Speed of light 300,000 km/second
• (186,000 miles/sec.)
• Distance to Earth 150 million km (93
  million miles)
• Radiation reaches us in about 8.3 minutes

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Radiation

• Radiation energy transferred in
  the form of electromagnetic waves
• no transfer of matter
• no material medium needed

Solar Constant 2 calories/cm2/minute
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Classifying Radiation

• Classified based on wavelength, ?

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The Electromagnetic Spectrum
Micrometers or microns (µ) 1/1 000 000 or 0.000
001 or 10-6 Hence Microwaves are about 1mm -
long.Radio waves are about a meter to 1000
meters long.
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Insolation
The suns energy distribution UV and shorter
7 Visible light 50 Infrared (IR) or longer
43 Thermal Infrared, the longest infrared,
heat. Microwaves (1 mm 30 cm) are used for long
distance communications. Radar is portion of
microwave. Microwave cooking discovered on Navy
ships. Takes 1/2 the energy of conduction or
convection ovens - more efficient. Why doesnt
microwave pass through window of oven? Gamma -
used for food safety. Discovered after nuclear
blasts.
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Radiation Laws

• All objects emit radiation.
• Hot objects emit more radiation
  (per unit area) than cold objects.

less radiation
more radiation
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Radiation Laws

• (Weins Law) The hotter the radiating body,
  the shorter the wavelength of maximum radiation.

Sun 6000ºC (11,000ºF) Earth 15ºC (60ºF)
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Getting through the atmosphereEnergy pathways
and principles

• Transmission
• Scattering
• Reflection
• Absorption
• Refraction

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Transmission
Direct radiation
Direct radiation

• Energy is passed through the atmosphere
• Energy/heat provided to the Earth system

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Scattering
Backscattering (albedo)
Scattering (diffuse radiation)

• Energy bounces off particles in the atmosphere.
  

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Scattering

• Scattering light
• short ? , ?scatter
• result?

Rayleigh Scattering selective scattering if dust
is about 1/10 the wavelength of light (.05
micron) VIB G YOR 4x 1x 1. sun appears
yellow as VIB is scattered out. 2. sky is blue
VIB is down-scattered and becomes prominent.

• ? distance , ?scatter
• result?

Mie Scattering white scattering, non-selective,
occurs with bigger particles, about 30x the
wavelengths of light. 1. salt crystals things
whiter at distance2. bluer sky at high elevation
- less white 3. white clouds.
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Reflection

• Albedo (?)
• reflective quality of a surface

Light color ? high ?
Dark color ? low ?

• Energy is bounced directly back
  out to space (energy loss to Earths
  system)

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Absorption

• ozone
• oxygen
• carbon dioxide
• water vapor
• liquid water / clouds

• Energy is absorbed (converted) by the atmosphere
  or the surface from radiation to heat
• Thermal (heat) energy created.

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Refraction

• Change in direction direction of radiation, by
  wavelength, in response to change in density of
  medium.

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Refraction

• Change in direction direction of radiation, by
  wavelength, in response to change in density of
  medium.

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Four Heat Transfer Mechanisms

• Conduction
• Convection
• Adiabatic Cooling and Warming
• Latent Heat in Phase Changes of H2O

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Conduction

• Molecule to molecule energy transfer
• When molecules collide, higher energy molecules
  excite lower temperature molecules, thereby
  transferring kinetic (heat) energy.

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Convection

• Heat is transferred by the movement, from place
  to place, of a gas or liquid. The principal
  motion is vertical. All heated gases and liquids
  experience this kind of mixing heat exchange.

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Adiabatic Cooling and Warming

• When air rises it expands and cools as its
  pressure is decreased. Thus, when it descends, it
  is warmed, as pressure increases. This change
  takes place without the addition or subtraction
  of energy from another source.

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Phase Changes (Latent Heat)

• Ice
• 80 calories/gram
• Water
• 585 calories/gram
• Water Vapor

Freezing
Melting
Sublimation
Releases Energy
Stores Energy
Sublimation
Evaporation
Condensation
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48 Units
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Key Points

• Electromagnetic radiation and spectrum
• Radiation laws and solar radiation
• Energy pathways and transfer principles
• Earth energy budget