Climate

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Climate Climate ChangeObjectives1. What
factors affect climate?2. What is El Nino how
does it work?3. What causes ice ages? 4. How
can scientists determine climate changes of the
past?
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Climate Long term weather of a region

• Depends on temperature precipitation
• 6 Climate Regions
• Tropical Hot wet or Hot w/ wet dry seasons
• Dry Desert
• Temperate marine humid w/ mild winters
• Temperate continental cold, snowy winters
• Highlands mt. regions, cool wet
• Polar tundra ice cap

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Climate Factors Affecting Temperature

• 1. Altitude Cooler _at_ higher altitudes
• 2. Latitude
• Cooler as you move away fr. equator.
• Same latitudes have similar temps (solar
  radiation)
• 3. Distance from bodies of water
• Water moderates temps. ? less variation
• Landlocked areas more extreme temps. (Hotter
  summers colder winters)

4. Ocean currents can influence temps. Warm
current ? milder winters (Gulf stream brings
warmer temps to UK) Cold current ? cooler summers
(California current brings cooler summer to San
Francisco)
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Climate Factors Affecting Precipitation.

• 1. Latitude
• Tropical air holds more moisture ? rainy
• 2. Distribution of air pressure systems global
  winds
• a. High Pressure Areas ? Dry sinking air (30 N
  S and poles)
• b. Low Pressure Areas ? Moist rising air (0
  60 degrees)
• c. Global Winds
• Wind from sea Carry moist air ? Wet climate
• Wind from land Dry Climate
• 3. Mt. Barriers
• Mts. Force warm moist air from sea up ?
  condenses precips. on one side of Mt. Dry on
  other side

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Mt. Barriers (Orogenic Uplift)

• WINDWARD SIDE
• Warm air is pushed up by mountain, condenses,
  precipitaties
• WET

• LEEWARD
• Dry Air on opposite side
• Desert - like

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• Mountain Barriers Climate
• Cascade Mts.

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Mountain Barriers Climate (Orogenic
Uplift) Note how the western side of the Cascade
Mts. (windward) are green with vegetation. The
eastern side of the Cascades (leeward) are brown
due to a lack of vegetation (Its dry on this
side of the mountain).
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Global Pressure Systems Climate
Low pressure latitudes Rainy/snowy High
pressure latitudes Dry
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Global Ocean Currents

• Warm currents (Gulf Stream) milder winters
• Cold currents (California Current) cooler
  summers

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CH. 24.7 Climate Change Seasonal El Nino
Natural Short Range Change in Climate
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El Nino year
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(No Transcript)
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El Nino year
La Nina cooler water
El Nino Warmer water
La Nina Opposite of El Nino Year when the cold
current off the coast of S. America is extra
cool.
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Climate Change What Causes a Planet to Warm Up
or Cool Down?
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Climate Change Ice AgesNaturally Occuring,
Long Term

• Ice Age Colder than usual glaciers cover
  larger portion of Earths surface as they advance
  fr. poles.
• When
• 4 major ice ages in last 2 million years
• Last one ended 10, 000 yrs ago

Scientific American Hot Planet, Cold Comfort
Planet http//www.youtube.com/watch?vTikUkmpWwBI

http//www.pbs.org/wgbh/nova/ice/chill.html http/
/courses.missouristate.edu/EMantei/creative/glg110
/glaciers.html
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Icehouse vs. Greenhouse
LOW 18O16O
HIGH 18O16O
ICE HOUSE Ice present _at_ poles
GREEN HOUSE NO ice present _at_ poles
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Causes of Ice Ages 1. Milankovitch Cycles
Changes in incoming solar radiation due to
variations in Earths orbit, tilt, or wobble. A.
Change in shape of Es orbit (How elliptical or
circular our orbit is. Varies from 0 6
elliptical Now 1.7 elliptical) Cycle 100
000 years More elliptical more variation in
climate ice age B. Changes in Tilt Ranges
from 22 24.5 degrees (Now 23.5 degrees) More
Tilt more seasonal variation ice age Cycle
41 000 yrs C. Changes in Wobble (direction of
axis). N. Pole pointed toward or away from sun?
Cycle 23, 000 years
www.atmo.arizona.edu/.../sec5/robust.html
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Causes of Ice Ages continued
2. Volcanic Activity Dust ash can cause
cooling in short term by blocking solar
radiation (ice age) Volcanic gases cause warming
over long term (b/c they are greenhouse gases)
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3. Changes in Solar Radiation (solar cycles)
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Ice Ages - Cause

• 55 Ma Uplift of the Himalayas
• Changes in continental arrangements
• Can change ocean currents or air flow ? can
  change climate
• Uplift of new land ? more weathering ? cooling

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Ice Ages Cause

• 5. Change in Thermohaline Circulation (melting
  sea ice changes salinity of water no sinking
  slow down of THC) ? change climate.

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Ancient Ice Age Snow Ball Earth
Ice covered Earth 2.4 bya (end of Precambrian
Time) Global temps - 74 F

• 6. Biology Driven Ice Age Snowball Earth
• Weaker sun (30 weaker) Arrival of
  photosynthesizing bacteria (removing CO2 from
  atmosphere) ICE
• ICE has high albedo --gt more solar radiation
  reflected --gt less energy absorbed --gt MORE ICE
• Volcanic GHG eventually warm planet up