C LIMATE 1. W HAT IS C LIMATE ? Climatology - study of earth’s surface climate and the factors...

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CLIMATE

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WHAT IS CLIMATE?

  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

Data is collected at 1000’s of locations is compiled for over 30 years to establish Normals or standard values

  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 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

  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  Temperate Zone - Temperature Moderate

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TEMPERATE ZONE23.5 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? Based on the climate and precipitation

and vegetation Continental Polar 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   Transition zones border the rainy tropics   Tropical wet distinct African Savannas Tropical dry dry season    

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DRY CLIMATES

Dry Climates - cover 30 % or earth - largest climate zone - where most of the deserts are located: Sahara, Gobies, Australian

  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 - Humid subtropical climate - influenced by

subtropical high pressure systems over oceans Southeast of the U.S.

-Marine west coast - dominated by the

constant inland flow of air from ocean- mild winters and cool

summers  -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.

  We are now in a interglacial period. Glaciers

covered from east to west and as far south as Indiana.

  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

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……. 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

  Convection currents strengthen - Northwest coast

of South America becomes warm and wetter.   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……

+ 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

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 La NiñaWeak Mod Strong Weak Mod Strong1953 1951 1957 1950 1970 19551958 1968 1965 1954 1998 19731963 1986 1972 1956 2007 19751969 1987 1982 1964 19881976 1994 1991 1971 19991977 2002 1997 1974 20102004 2009 19832006 1984

199520002005

2011

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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

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

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