Weather and Climate

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Weather and Climate

• Preview
• Section 1 Factors Affecting Climate
• Section 2 Weather Factors
• Section 3 Climate and Vegetation Patterns
• Chapter Wrap-Up

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Section 1 Factors Affecting Climate

• Read to Discover
• How does the Sun affect Earths atmosphere?
• How does atmospheric pressure distribute energy
  around the globe?
• How do global wind belts affect weather and
  climate?
• How do the oceans affect weather and climate?

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Section 1 Factors Affecting Climate
Question By which processes does the Sun
interact with Earths atmosphere?
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Section 1 Factors Affecting Climate
The Suns Effect on Earth
The greenhouse effect helps keep the planet warm.
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Section 1 Factors Affecting Climate
Atmospheric Pressure

• Low-pressure zones are caused by warm air, which
  expands and rises.
• High-pressure zones are caused by cold air, which
  is dense and sinks.
• Pressure differences cause airflow and energy
  distribution around the globe.
• Warm air moves through the upper atmosphere until
  the air cools and falls cold air sinks toward
  Earths surface and then heats up and rises.

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Section 1 Factors Affecting Climate
Global Winds

• Pressure differences cause wind.
• Winds move heat and cold across Earths surface.
• Prevailing winds blow from the same direction
  most of the time, causing similar weather.
• A front occurs when two air masses of widely
  different temperatures or moisture levels meet.

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Section 1 Factors Affecting Climate
Oceans

• Water heats and cools more slowly than land,
  making coastal areas milder than inland areas.
• Ocean currents move heat between the tropics and
  polar regions, helping to maintain Earths energy
  balance.

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Section 2 Weather Factors

• Read to Discover
• What are the common forms of precipitation, and
  how are they formed?
• How do mountains and elevation affect weather and
  climate?
• What are the different types of storms, and how
  do they form?

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Section 2 Weather Factors
Question What are the steps in the formation of
precipitation, and what are the four common
types of precipitation?
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Section 2 Weather Factors
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Section 2 Weather Factors
Forms of Precipitation

• RainLiquid formed through condensation of water
  vapor
• SnowIce crystals formed in clouds
• SleetRain that freezes as it falls
• HailChunks of ice formed in storm clouds

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Section 2 Weather Factors
Question How do mountains and elevation affect
weather and climate?
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Section 2 Weather Factors

• Increase in elevation causes drop in temperature.
• Mountains cause orographic effect Moist air
  meets a barrier and is pushed upward, causing
  cooling, condensation, and precipitation.
• Mountainside facing wind is the windward, wetter
  side side facing away from wind is the leeward,
  drier side, called the rain shadow.

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Section 2 Weather Factors
Types of Storms

• Middle-latitude storms form when cold, dry polar
  air mixes with moist, warm tropical air. Examples
  include thunderstorms and tornadoes.
• Tropical storms are usually smaller and lack
  fronts. Examples include hurricanes and typhoons.

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Section 3 Climate and Vegetation Patterns

• Read to Discover
• How do the two tropical climates differ?
• What conditions are common in dry climates?
• What climates are found in the middle latitudes?
• What characterizes high-latitude and highland
  climates?

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Section 3 Climate and Vegetation Patterns
Question What are the characteristics of
tropical humid and tropical wet and dry climates?
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Section 3 Climate and Vegetation Patterns
Tropical Wet and Dry Climates
Tropical Humid Climate

• Close to equator
• Warm temperatures
• Rainfall all year
• Receives Suns rays directly all year
• Rising warm air
• Rain forests
• Monsoons

• North and south of tropical humid
• Caused by seasonal change in this
  area
• Alternating wet and dry seasons
• Savannas

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Section 3 Climate and Vegetation Patterns
Dry Climate Areas

• Generally centered about 30 degrees north and
  south of equator
• Subtropical high-pressure zone causes sinking dry
  air, with little rain.
• Winters may be very cold, summers very hot.
• Hardy plants and animals

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Section 3 Climate and Vegetation Patterns
Middle-Latitude Climates

• MediterraneanLong, dry summers and mild winters
  scrub woodland vegetation
• Humid SubtropicalHot, humid summers and mild
  winters temperate forests
• Marine West CoastMild all year may support
  dense forests
• Humid ContinentalVariable, with four seasons
  enough rain to support forests

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Section 3 Climate and Vegetation Patterns
High-Latitude and Highland Climates

• SubarcticLong, cold winters and short, warm
  summers vast evergreen forests
• TundraLong winters, with permafrost low shrubs,
  lichens, mosses, ferns
• Ice CapPolar climates few land plants or
  animals
• HighlandVaries by elevation, with low elevations
  relatively mild and high elevations similar to
  ice cap

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Chapter Wrap-Up Understanding the Main Ideas

1. How does latitude relate to climate?
2. How do atmospheric pressure zones and ocean
   currents affect Earths energy balance?
3. On a global scale, where is precipitation most
   common?
4. What effects can hurricanes have on local
   environments?
5. Where will you find climates that are generally
   warm and wet all year? What creates dry weather
   conditions in arid regions?