Climate

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Chapter 18
Climate
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CLIMATE

• General conditions of temp precipitation for an
  area over a long period of time.
• Southwest US hot, dry all year.

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• Climate of a region is determined by
• 1. Temperature
• 2. Precipitation

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FACTORS THAT AFFECT TEMP

• Latitude- measure of the distance N S of
  equator.
• Closer to equator, more direct sunlight, warmer
  climate.
• Farther away from equator, less sunlight, cooler
  climate.

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• 2. Elevation- as elevation increases, air cools
  cant hold as much moisture so temp decreases.

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OCEAN CURRENTS

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• 3. Ocean Currents- a river of water that flows in
  a definite path in the ocean.
• The surface temp of water affects the temp of the
  air.

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• Warm water currents travel away from equator.
• Cold water currents travel toward the equator.
• Land near currents is affected by the temp of the
  ocean currents.

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4. Distances From Water

• Oceans greatly moderate the temps of nearby land.
• Water heats/cools slower than land.

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FACTORS THAT AFFECT PRECIPITATION

1. Prevailing Winds- Carries different amounts of
   moisture which affects precipitation.

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• Winds that blow from sea to land carry more
  moisture.
• Places in the center of a land mass have dry
  climates.

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DESERT

• Region that receives less than 25cm of
  precipitation in one year.

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2. MOUNTAIN RANGES

• Act as barriers to winds
• Mountains cause air to rise
• 2 parts of a mountain windward side leeward
  side

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• A) Windward side- receives a lot of
  precipitation. Faces the wind. B) Leeward side-
  drier air. Faces away from wind.

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How Mtns. Affect Precip.

• Air is forced up. As it rises, it starts to cool.
• Cold air cant hold as much moisture so
  precipitation occurs on the windward side.
• Air that comes over the Mtn. (leeward side) is
  drier.

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3. SEASONAL WINDS

• Monsoon- a major landbreeze or seabreeze that
  changes direction with the seasons.

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THE SEASONS

• Most places outside the tropics have 4 seasons
  summer, fall, winter, spring.

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Causes of Seasons

• Tilted Axis- the tilt of the earths axis as the
  earth travels around the sun.
• Tilted on an angle of 23.5

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• The north end of the axis is pointed away from
  the sun for part of the year (Winter) toward the
  sun for another part of the year (Summer).

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• In summer, N. hemisphere is tilted towards the
  sun more direct sunlight, warmer temps. (June)
• In the winter, N. Hemisphere is pointed away from
  sun less sunlight, colder temps. (December)

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Sec. 2 Climate Regions
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CLASSIFICATION

• Climates are classified according to
• 1. Temperature
• 2. Precipitation

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6 Main Climate Regions

1. Tropical rainy
2. Dry
3. Temperate marine
4. Temperate continental
5. Polar
6. Highlands

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1. Tropical Rainy Climates

• Found in low-lying lands near equator.
• 2 types Tropical Wet, Tropical Wet--Dry.

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Tropical Wet

• Hot/Humid, many rainy days, over 10meters/year.
• Windward side of Hawaii
• Rain Forest- forests in which large amounts of
  rain fall year-round.

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Tropical Wet Dry

• Hot, receives slightly less rain has a distinct
  dry rainy season.
• Savannas- tropical grassland
• Southern Florida

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2. Dry Climates

• A climate is dry if the amount of precipitation
  that falls is less than the amount that
  evaporates.
• Arid Climate Semiarid Climate.

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Arid Climate

• Desert, with little precipitation (less than
  25cm/year).
• Hot, sandy cold or rocky
• Parts of California Southwest.

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Semiarid Climate

• Dry but receives 25-50cm of precipitation/year.
• Steppe- dry region that gets enough rainfall for
  short grasses bushes to grow.
• Great Plains

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3. Temperate Marine Climate

• Along the coasts of temperate continents
• Humid (50F) in summer mild winters (20F to
  64F).
• Mediterranean, Humid Subtropical, Marine West
  Coast.

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Mediterranean

• Coastal climate that is drier warmer than West
  Coast Marine.
• Mild winters, cool summers, moderate rainfall.
  (agriculture)
• Southern California,

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Marine West Coast

• Warm, dry summers rainy winters
• Northern California to Southern Alaska
• Because of heavy precipitation, thick forests
  grow here.

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Humid Subtropical

• Hot/Humid summers cool winters. Warm wet.
• Southeast US
• Forests, oranges, peaches, sugarcane.

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4. Temperate Continental Climate

• Only found on continents in the Northern
  Hemisphere.
• Not influenced by oceans- you get extreme temps.
• 50F or above to 20F or below

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Humid Continental

• Hot, humid summers cold winters with moderate
  precipitation year round.
• NE United States, Mid West US.

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Subarctic

• Short, cool summers long, cold winters with
  light precipitation.
• Eastern Alaska, Canada

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5. Polar Climate

• Coldest climate, Avg. temps below 50F in warmest
  month.
• Includes North South Poles, Icecaps, tundras.

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Tundra

• Stretches from northern Alaska, Canada, Russia.
  
• Short cool summers, bitterly cold winters.

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PERMAFROST

• Permanently frozen land, water cannot drain away
  so the soil is wet boggy in summer.
• No trees, but moss/grass/shrubs grow.

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6. Highlands Climate

• Cooler wetter than nearby lowlands.
• Temp decreases with altitude.
• Short summers, long, severe winters. NW US.

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Sec. 3 Long-Term Changes
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Studying Climate Changes

• If plants or animals today need certain
  conditions to live, then similar plants animals
  in the past also required those conditions.

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Types of Evidence to Study Climate Changes

• Fossil evidence
• Tree rings
• Pollen

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Tree Rings

• Scientists study the pattern of thick or thin
  tree rings to tell about warm/cool or wet/dry
  climate.

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Ice Ages

• Cold periods, Glacial episodes.
• Huge sheets of ice (glaciers) cover large parts
  of the Earths surface.

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• Last Ice Age was 10,500 yrs ago. Sheets of ice
  covered N Europe, North America as low as
  Indiana Iowa.
• A lot of water was frozen causing ocean level to
  drop.

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CAUSES OF CHANGE

1. Earths position
2. Solar energy input
3. Volcanic Activity
4. Movement of Continents

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Section 4
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Short-Term Climate Changes

• 1. Ocean Currents- El Nino, La Nina
• 2. Global Warming
• 3. Ozone Depletion

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El Nino

• Unusual pattern of warm winds water that form
  over the Pacific Ocean move eastward towards
  the coast of South America.
• Brings severe conditions- rain or drought.

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La Nina

• Surface waters of eastern Pacific Ocean are
  colder than usual.
• Brings colder winters greater precipitation to
  Pacific NW North Central US.
• Greater hurricane activity in western Atlantic
  Ocean.

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GLOBAL WARMING

• A gradual increase in temp. of earths
  atmosphere.
• Greenhouse effect
• Greenhouse gases carbon dioxide, methane trap
  heat.
• Human activities add greenhouse gases to the
  environment.

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Ozone Depletion

• Chlorofluorocarbons (CFCs) are a major cause for
  depletion.

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• CFCs in air conditioners/aerosol sprays release
  CFCs into the air they stay in the atmosphere
  breakdown the ozone layer.