Solar Energy

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Solar Energy

• The Planetary Energy Balance

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• So, the question is,
• With all that sunlight beating down on us, why
  doesnt Earth get a lot hotter?

And the answer is . What comes in, must go
out This is the planetary energy balance.
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Shortwave radiation energy from the sun (solar
energy) enters the Earth surface and atmosphere
system. It is ultimately returned to space as
longwave radiation (heat energy, also called
infrared radiation). A basic necessity of this
energy interchange is that incoming shortwave
(solar) radiation and outgoing longwave (heat)
radiation be equal in quantity.
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Both shortwave and longwave radiation are forms
of electromagnetic radiation. All objects above
the temperature of absolute zero (-273.15
Celsius) radiate energy to the surrounding
environment. The amount of electromagnetic
radiation emitted by a body is proportionally
related to its temperature. The higher the
temperature, the more radiation emitted. Visible
light is only part of the electromagnetic
spectrum of radiation.
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Electromagnetic spectrum of radiation
Shortwave radiation
The visible portion of the electromagnetic
spectrum of radiation.
Longwave radiation
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Incoming Shortwave Radiation
Okay, so the next few slides are going to scare
the er well, you know what it will scare out
of you. Just relax, breathe, take your time, and
drop your centre. Youll get it.
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Incoming Shortwave Radiation
Some is reflected this is the albedo 462030
units
Total added to Earth-atmosphere system by
incoming shortwave radiation is 70 units.
(195170)
Some is absorbed by the atmosphere 21719 units
Therefore, 19 (atmospheric absorption) 51
(ground absorption) 30 (albedo) 100
Some is absorbed by the ground 282351 units
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Incoming shortwave solar radiation that is
absorbed by either the ground or the atmosphere
is re-radiated as longwave radiation. For Earths
temperature to be in balance, what comes in as
shortwave radiation energy and is absorbed must
equal what goes out as longwave radiation.
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Outgoing Longwave Radiation
66470 total longwave lost to space
This is the same amount that is added to Earth
through incoming shortwave radiation.
The Greenhouse Effect
http//www.physicalgeography.net/fundamentals/7i.h
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• So, what you need to know from this slide show
• Difference between shortwave and longwave
  radiation
• Part of electromagnetic spectrum
• Amount of energy that gets added to the
  Earth-atmosphere system, and how.
• How energy is lost from the Earth-atmosphere
  system.
• How incoming solar radiation must be balanced by
  outgoing longwave radiation.

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Have you seen a sun catcher?