Weather and Climate

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Weather and Climate
CHAPTER 3

• Section 1 Factors Affecting Climate
• Section 2 Weather Factors
• Section 3 Climate and Vegetation Patterns

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Objectives
Section 1Factors Affecting Climate

• 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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Effect of the Sun on Earths atmosphere
Section 1Factors Affecting Climate

• Some solar energy, in the form of heat, reflects
  off Earth back into the atmosphere.
• Atmosphere traps this heat energy in a process
  called the greenhouse effect.
• Process helps keep the planet warm.

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Atmospheric pressure and energy distribution
Section 1Factors Affecting Climate

• 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 air flow and energy
  distribution around the globe.
• Warm air moves through the upper atmosphere until
  it cools and falls cold air moves along Earths
  surface until it heats up and rises.

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Global winds affect weather and climate
Section 1Factors Affecting Climate

• Pressure differences cause wind.
• Winds move heat and cold across the 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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Oceans affect weather and climate
Section 1Factors Affecting Climate

• 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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Objectives
Section 2Weather Factors

• 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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Forms of precipitation
Section 2Weather Factors

• 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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Effects of mountains and elevation on weather and
climate
Section 2Weather 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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Types of storms
Section 2Weather Factors

• 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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Objectives
Section 3Climate andVegetation Patterns

• 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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Differences in the two tropical climates
Section 3Climate andVegetation Patterns

• Tropical humid climate
• close to equator
• generally warm and wet year-round
• climate supports dense rain forests
• Tropical wet and dry climate
• farther from equator north and south of the
  tropical humid zone
• warm wet season alternates with cooler, drier
  season
• seasonal variation supports savannas tropical
  grasslands with scattered trees and shrubs

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Dry climate areas
Section 3Climate andVegetation Patterns

• generally centered about 30 degrees north and
  south of equator
• subtropical high-pressure zone causes sinking dry
  air, with little rain
• winters may be cold, summers very hot
• hardy plants and animals

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Middle-latitude climates
Section 3Climate andVegetation Patterns

• Mediterraneanlong, dry summers and mild winters
  scrub woodland vegetation
• humid subtropicalhot, humid summers and mild
  winters temperate forests
• marine west coastmild year-round may support
  dense forests
• humid continentalvariable, with four seasons
  enough rain to support forests

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High-latitude and highland climates
Section 3Climate andVegetation Patterns

• subarcticlong cold winters and short warm
  summers vast evergreen forests
• tundralong winters, with permafrost low
  vegetation
• ice cappolar climates, with few plants or land
  animals
• highlandclimate varies by elevation, with low
  elevations relatively mild and high elevations
  similar to ice cap