Transcript Climate - cloudfront.net

CLIMATE
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WHAT IS CLIMATE?
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Climatology - study of earth’s surface climate
and the factors that affect the past, present and
future climate changes.
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CLIMATE DESCRIBES
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AVERAGE PRECIPITATION PATTERNS
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U.S. PRECIPITATION PATTERNS
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NORMALS
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Data is collected at 1000’s of locations is compiled
for over 30 years to establish Normals or
standard values
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Must be used with caution Why?
 1) Weather conditions may differ from Normals
 2) Normals not intended to describe usual
weather condition
 3) Normals only apply to specific areas
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WHAT CAUSES CLIMATE?
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THREE MAIN FACTORS
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LATITUDES
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Amount of solar radiation varies place to place. Why?
Earth is tilted on its axis and it affects how the sun’s rays
strike the earth
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23.5 S to 23.5 N - Tropics - receives the most sun .
Temperature warm year round
 23.5 N- 66.5 N
 23.5 S- 66.5 S
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Temperate Zone - Temperature Moderate
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TEMPERATE ZONE
23.5 N – 66.5 N AND 23.5 S – 66.5 N
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LATITUDES CONT……. 66.5 N AND 66.5 S POLAR ZONE SUN STRIKES AT LOW
ANGLES/COLD TEMPERATURES.
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TOPOGRAPHY EFFECTS
H2O heats up and cools down more slowly than
land. Coastal regions are warmer in winter and
cooler in the summer than inland areas of similar
latitudes.
 Temperature in lower atmosphere decreases with
altitude.
 Orographic lifting - air rises over mountain,
rising air cools and condenses then drops
moisture.
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TOPOGRAPHY EFFECT
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Air Masses
 2 courses of weather movement interactions of
air masses - air masses affect climate tool
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AIR MASSES OF N. AMERICA
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Region and Origin
 Caused by difference in the amount of solar
radiation. Average weather conditions in or near
air masses are fairly similar to conditions.
Exhibited by air masses.
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SUN RAYS HITTING THE EARTH
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SUN RAYS IN RELATIONSHIP TO LATITUDE
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CLIMATE CLASSIFICATION
How are climates classified?
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Based on the climate and precipitation and
vegetation
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Continental
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Polar
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High elevations
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WORLD CLIMATES
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Tropical Climate - 600 cm of rainfall
 Heat + rain = rainforest under the influence of
maritime tropical air
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Transition zones border the rainy tropics
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Tropical wet
 Tropical dry
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distinct
dry season
African Savannas
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DRY CLIMATES
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Dry Climates - cover 30 % or earth - largest
climate zone - where most of the deserts are
located: Sahara, Gobies, Australian
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Continental Tropical dominates
-low precipitation
-vegetation scarce
-intense solar radiation
-high rate of evaporation - few clouds
-2 subtypes: arid region (deserts)
Semi and steppes
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MILD CLIMATES
3 subtypes
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- Humid subtropical climate - influenced by
subtropical high pressure systems over oceans
Southeast of the U.S.
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-Marine west coast - dominated by the constant
inland flow of
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air from ocean- mild winters and cool summers
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-Mediterranean - Italy, Spain - summers warm lack of cool ocean currents in the Mediterranean Sea
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POLAR CLIMATES
Coldest regions on earth  mean temperature of warmest month is
lest than 10°C  precipitation is low  cold air does not hold cold moisture.
 Amount of heat radiates from earth is low
thus there are no convection currents
necessary to release precipitation.
 Variations - high elevations, includes
parts of Andes Mountains of South
America
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MICRO CLIMATE- LOCALIZED CLIMATE
WITHIN A MAIN REGIONAL ONE.
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MICROCLIMATE
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HEAT ISLANDS-CLIMATE IS WARMER THAN THE
SURROUNDING RURAL AREAS.
climate is warmer than the surrounding
rural areas.
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Ice Ages - Earth surface was totally covered by
vast sheets of ice. Average global temperature
decreased by 5°C sparked the advancement of ice
sheets. Interglacial Intervals = alternating of
cold/warm periods.
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We are now in a interglacial period. Glaciers
covered from east to west and as far south as
Indiana.
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Retreat - scoured the Finger Lakes of New York
/ Great Lakes - Michigan
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NORTH AMERICA ICE AGE COVERAGE
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ICE AGE COVERAGE OF THE WORLD
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EUROPE ICE AGE COVERAGE
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SEASONS
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Seasons - short term climate changes caused by
regular variations in daylight, temperature and
weather patterns. Summer - North Pole titled
toward sun - Northern Hemisphere / Southern
Hemisphere - winter
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WHY DO WE HAVE SEASONS?
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DEGREE OF INCOMING SOLAR
ENERGY
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SEASONS IN THE LATITUDES
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EL NINO CONT…….
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Warm currents that occasionally develops off the
western coast of South America normally.
No reason - Trade winds weaken - allows warm
winters from the Western Pacific surge eastward
towards the South American coast
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Convection currents strengthen - Northwest coast of
South America becomes warm and wetter.
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Jet Stream moves south. Weather system take a
southern track - storms in California and Gulf Coast
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EL NINO
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EL NINO CONT……
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+ positive effect - strong upper winds keep the
tropical disturbances down
Change can be Natural Past climate changes found studying tree rings, ice core samples,
fossils and radioactive carbon.
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LA NINA- CHARACTERIZED BY UNUSUALLY
COLD OCEAN TEMPERATURES IN THE
EQUATORIAL PACIFIC
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a. La Niña often causes drought conditions in the
western Pacific; flooding in northern South America;
mild wet summers in northern North America, and
drought in the southeastern United States.
El Niño
Weak
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1958
1963
1969
1976
1977
2004
2006
Mod
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1968
1986
1987
1994
2002
2009
La Niña
Strong
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1965
1972
1982
1991
1997
Weak
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1954
1956
1964
1971
1974
1983
1984
1995
2000
2005
2011
Mod
1970
1998
2007
Strong
1955
1973
1975
1988
1999
2010
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LA NINA
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Changes in the earth’s climate is caused by:
 1) Solar activity
 2) Changes in the earth’s tilt
 3) Earth’s orbit
 4) Volcanic eruptions
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SOLAR ACTIVITY- SUNSPOTS
Low sunspot activity - Maunder Minimum
(“Little Ice Age”) cold dramatic conditions.
 High sunspot activity - Temperatures are
warmer - Earth’s orbit - shape of the earth’s
elliptical orbit changes and becomes more
elliptical than circular.
 If the orbit elongates the earth is closer to the
sun. Temperature is cooler.
 The earth’s tilt is 25.3° and it tends to vary from
22.1° to 24.5° every 41,000 years.
 Changes in the tilt causes seasons to be more
severe - winters-warmer, summers cooler.
Colder weather causes ice sheets to expand
causes ice age
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SUN SPOTS
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EARTH WOBBLE
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Earth wobbles as it spins - axis point towards
North Star “Polaris”. When earth wobbles, axis
tilts towards star “Vega” when winter extends.
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The Northern Hemisphere is the farthest from
the sun while the Southern Hemisphere is the
closest and enjoying summer.
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VOLCANIC ACTIVITY
Tiggers climatic change
 Dust suspended in the atmosphere for several
years blocking out the incoming solar radiation.
 Lowering global temperatures
 High active periods of volcanos, the planet tends
to have cooler temperatures
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HUMAN FACTOR TO CLIMATE CHANGE
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Greenhouse Effect
Retention of heat by the atmosphere by the accumulation
atmospheric gases called Greenhouse gases
water vapor, carbon dioxide, methane, nitrous oxide, and
ozone.
Greenhouse gases greatly affect the temperature of the
Earth; without them, Earth's surface would average about
33°C colder than the present average of 14 °C (57 °F).[
Since the beginning of the Industrial Revolution, the
burning of fossil fuels has contributed to a 40% increase in
the concentration of carbon dioxide in the atmosphere from
280 ppm to 397 ppm, despite the uptake of a large portion
of the emissions by various natural "sinks" involved in the
carbon cycle.
Anthropogenic carbon dioxide (CO2) emissions (i.e.,
emissions produced by human activities) come from
combustion of carbon based fuels, principally wood, coal,
oil, and natural gas.[7]
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GLOBAL WARMING
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