Climatic Changes

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Climatic Changes
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Standards

• 4d Students know the differing Greenhouse
  conditions on Earth, Mars and Venus the origins
  of those conditions and the climatic
  consequences of each.
• 5g Students know the features of the ENSO cycle
  in terms of sea-surface and air temperature
  variations across the Pacific and some climatic
  results of this cycle.

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Seasons

• Short-term periods of climate change caused by
  regular variations in daylight, temperature and
  weather patterns
• Variations are due to changes in the amount of
  solar radiation an area receives
• Once Earth revolves at a tilt, different areas of
  earth receive changing amounts of solar radiation

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Seasons
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Effects of Latitude

• Middle latitudes have fairly constant solar
  radiation so there is little change in seasons.
  There are changes in wet and dry seasons
• Higher latitudes near the poles experience great
  differences in temperature and in number of
  daylight hours.

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South North Poles

• During the summer the North Pole is tilted toward
  the sun, at this location there are 24 hours of
  daylight for six months
• At the same time in the South Pole experiences 24
  hours darkness

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El Nino

• Occurs every three to five years and lately more
  often
• During El Nino the Pacific Ocean warms along the
  equator
• Near the equator trade winds blow east to west
  weaken and sometimes reverse.

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El Nino Cont.

• Instead of cold water rising off the coast of
  Peru, the change in the trade winds allows warm
  tropical water in the upper layer of the Pacific
  to flow eastward to South America
• Ocean temperatures increase by 1 degree C to 7
  degrees C off the coast of Peru.
• Sea levels rise

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However, El Nino..

• Does not directly cause unusual weather but
  instead affects the atmosphere and the ocean to
  make stormy weather more likely.

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Climatic Change

• Earlier geologic eras show that Earth was
  sometimes much colder or warmer than it is today
• Glaciers have covered large parts of Earths
  surface
• These periods of extensive glaciers are called
  ice ages
• Ice ages alternate with warm periods called
  interglacial intervals

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Greenhouse Effect

• Natural heating caused by gases in our atmosphere
  trapping heat
• Carbon dioxide is the main greenhouse gas

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Global Warming

• Global temperatures are rising
• Increased greenhouse gases increase the
  greenhouse effect
• Temperatures on Earth have risen ½ degree C in
  the last 100 years

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Global warming has a huge effect on Earth!
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Greenhouse warming
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What about other planets?

• Venus
• Most similar to earth in physical properties such
  as mass, diameter and density
• Average surface temperature is 464C
• The atmosphere is mainly Carbon Dioxide and
  Nitrogen.
• Causes a highly efficient Greenhouse Effect
  resulting in very high temperatures.
• It has clouds made of sulfuric acid
• The atmospheric pressure is 92 atmospheres,
  compared to 1 atmosphere at sea level on Earth.

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What about other planets?

• Mars
• The planet is smaller and less dense than Earth.
• The density and atmospheric pressure on Mars is
  much lower than Venus
• There is a very thin atmosphere
• 95 Carbon Dioxide
• 5 Oxygen, Nitrogen, Argon
• Because of this Mars does not have the strong
  Greenhouse Effect found on Venus.
• Mars has high turbulent winds

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The Coriolis Effect

• It is important because
• It controls the global circulation patterns of
  the atmosphere
• Climate zones
• Rainfall patterns
• Surface wind patterns
• It affects global ocean circulation patterns
• Coastal currents
• Westward intensification of coastal currents
• Heat transport from equator to the poles
• It affects ocean mixing through the Eckman Spiral
• Upwelling
• Surface mixing

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To understand Coriolis, we

• Use the analogy of a carousel with two people
  playing catch.
• The carousel rotates during the game
• Analogous to earth rotation
• We observe the game of catch as if we were seeing
  it from
• 1. A high, fixed platform (analogous to outer
  space).
• 2. A platform that rotates with the carousel
  (analogous to our location on the rotating
  earth).
• Play Video

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Limitations of the analogy

• The analogy is that the earth is represented by
  the carousel and the fixed observer is an
  inertial frame of reference, where objects
  travel in straight lines.
• The observation is from above, so it only applies
  to the earth if the carousel is at the north or
  south pole.

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Coriolis on the Earth

• Mass in motion curves to the right in the
  Northern Hemisphere and to the Left in the
  Southern Hemisphere.
• The Coriolis effect is strongest at the poles and
  weakest at the equator.

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Atmospheric Circulation if earth doesnt rotate
If the earth were a non-rotating sphere, air
circulation would be in a single Northern
Hemisphere cell and in a single Southern
Hemisphere cell. In each cell, heated air would
rise at the equator and move toward the polar
regions, where it would cool, sink, and be drawn
back to the warmer regions of the equator.
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Review Sheet

• What are seasons?
• Explain how the tilt of the earth effects
  seasons.
• How does El Nino occur?
• What is the effect of El Nino?
• In depth explain the Greenhouse effect and the
  impact of earth.
• Why is global warming occurring and how does it
  effect earth?