Insolation

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Insolation

• INcoming SOLar radiATION
• Strength is dependent on
• Angle of insolation
• Duration of insolation
• Type of surface receiving the insolation

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EM Energy Interactions in Environment

• Refracted bent as pass through
• Reflected bounced off
• Scattered refracted or reflected in various
  directions
• Transmitted passed through
• Absorbed taken into

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Electromagnetic Spectrum

• Organisms vary in their ability to sense
  different parts of the spectrum.

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Angle of Insolation

• A measure of how high the Sun is in the sky
• The higher the Sun, the more direct the Suns
  rays.
• The more direct the rays, the greater the amount
  of insolation.
• What time of day is insolation the greatest?

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• Angle changes throughout the year
• In Northern Hemisphere Rays are most direct in
  summer.
• Direct rays strike the Tropic of Cancer on the
  Summer Solstice.
• What time of the year is insolation the greatest
  in the S. Hemisphere?

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• As you travel poleward, the angle of insolation
  decreases.
• How does this affect global heating?
• How do temperatures compare between the tropics
  and the poles?
• This difference in heating drives the Earths
  weather systems.

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Effect of Angle of Insolation
Same amount of incoming energy. The more direct
the angle the more concentrated the energy
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Equator
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Poles
Relative amount of incoming energy
__________
_____________________________
_____
______
Greater the angle, the less concentrated the
energy
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Intensity of insolation depends upon

• Latitude
• Farther you are from the equator the less energy
  reaches you

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Same area covered Different amounts of energy
Less energy colder
More energy warmer
Less energy colder
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• Season
• More energy reaches you in summer than in winter

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Monthly Insolation Values
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Annually, energy transfers from the Equator to
the Poles on a global scale.
Watch how this happens over a year!....
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JANUARY
-10.0 0.8 11.6 22.4
33.2 (oC )
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FEBRUARY
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MARCH
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APRIL
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MAY
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JUNE
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JULY
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AUGUST
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SEPTEMBER
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OCTOBER
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NOVEMBER
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DECEMBER
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JANUARY
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Duration of Insolation

• This is the length of daylight in a day.
• The longer the amount of daylight, the greater
  the amount of insolation.
• What time of year has the longest hours of
  daylight?

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Length of Daylight
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Absorption of Insolation

• Absorption depends on texture and color.
• The rougher the texture, the more absorption
  takes place.
• Darker colors absorb insolation at a greater rate
  the lighter colors.
• Which absorbs more? A blacktop parking lot or a
  snowy field?

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• Since dark colors absorb heat radiation then
  light colors reflect radiation.
• Light energy reflected from a surface is called
  albedo.
• Surfaces with high albedo reflect a lot of light
• For instance, snow has a high albedo. The
  surface of the moon has a high albedo. A mirror
  has a high albedo.
• Name a type of surface with a low albedo.

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Albedo of selected surfaces
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Presence of cloud cover

• Clouds absorb and reflect some incoming energy.
  In the day, less heat will reach the ground
• At night, clouds act as blankets to prevent heat
  from returning to space

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Effect of Angle of Insolation

• More energy reaches the equator than the poles
• There is a gain of energy at the equator
• There is a loss of energy at the poles
• Unequal heating of earth causes giant convection
  cells to form
• Result global winds

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Winds and Ocean Currents

• The energy of the earth is not static
• It can be transferred either by winds or ocean
  currents.
• Most of the insolation reaches the earth and
  heats up the oceans and the seas
• Temperatures of areas near the coast are
  modified. Example Vancouver and Ottawa

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Formation of convection cells
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• Warm air rises
• Cool air sinks
• Convection cells form
• Earth is spinning adds another factor in
  formation of global winds
• Coriolis effect

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Coriolis Effect

• objects moving in the northern hemisphere are
  deflected toward the right of their direction of
  motion
• Objects moving in the southern hemisphere are
  deflected toward the left of their direction of
  motion

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Resulting wind pattern is called3-celled model
of global air circualtion
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Review

• What is insolation?
• What are 3 things that affect insolation?
• What time of day is insolation the greatest?
• What time if year is insolation the greatest?
• How does latitude affect insolation?

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Review

• How does color affect absorption of radiation?
• What is albedo?
• Name a surface that has high albedo.

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Lag Time of Maximum Heat

• The maximum heat produced by the Sun does not
  occur at the same time as maximum insolation
• This is due to the time it takes for the object
  or surface to heat up.

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Dec 21
June 21
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• So, even though maximum insolation is in June,
  the warmest month is July/August due to the time
  it takes for the atmosphere to warm to the max.
• The same is true for daily heating. Even though
  the maximum insolation is at noon, the hottest
  time of day is late afternoon

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The Greenhouse Effect

• The greenhouse effect is the rise in temperature
  of Earths atmosphere.
• This rise is caused by certain gases.(Water
  vapor, carbon dioxide, nitrous oxide, and
  methane, for example)

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Greenhouse Effect cont.

• These gases trap energy from the sun.
• Without these gases, heat would escape back into
  space and Earths average temperature would be
  about 60ºF colder.
• Because of how they warm our world, these gases
  are referred to as greenhouse gases.

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Global Warming

• This is NOT the same as the Greenhouse Effect
• This is due, in part, to a build up of greenhouse
  gases.
• The increase in theses gases are due, in part, to
  human influences.

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Review

• Why is the hottest part of the day not the same
  as the time of maximum insolation?
• What is the Greenhouse Effect?
• What are some greenhouse gases?
• Is the Greenhouse Effect the same as Global
  Warming?
• What is Global Warming?