Weather and Climate Chapter 17 and sections of Chapter

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Weather and Climate

• Chapter 17 and sections of Chapter 9

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Atmosphere Composition

• Mixture of gases- 78 Nitrogen, 21 oxygen, 1
  other gases.
• The biggest component of the other gases is
  carbon dioxide-.3.
• Oxygen and carbon dioxide are exchanged by
  photosynthesis and respiration.

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Atmosphere Formation

• The early atmosphere had mostly hydrogen and
  helium. NO OXYGEN!
• Volcanoes blew those gases from the atmosphere
  and replaced with different gases which included
  carbon dioxide.
• Photosynthesis began to convert carbon dioxide
  into oxygen.

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Atmosphere Structure

• The atmosphere is in 4 layers troposphere,
  stratosphere, mesosphere, and exosphere
• In the troposphere, the temperature decreases
  with altitude and all weather occurs here.
• In the stratosphere, temperature increases with
  altitude and the ozone layer is in this layer.

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atmosphere
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Heating of the Atmosphere

• The atmosphere is heated three ways radiation,
  conduction, and convection
• Radiation- heating using electromagnetic waves.
  This is how the sun heats the atmosphere.

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Water in the Atmosphere

• Water is present in all three states of matter
  solid (ice), liquid (rain), and gas (vapor).
• Water is transferred around the globe by the
  water cycle.
• The water is controlled by the sun and gravity.

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Precipitation
Condensation
Evaporation
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Evaporation

• The process where water is changed into a gas.
• This process is a cooling process where the
  temperature will drop.
• This puts water into the atmosphere.
• Transpiration is how plants put water into the
  atmosphere.

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Condensation

• This process converts water vapor into a liquid.
• This is a heating process. It gives off heat to
  the atmosphere.
• This process makes clouds.

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Precipitation

• The joining of the condensed water molecules in
  the clouds to form drops.
• When the drops get large enough, it rains,
  sleets, snows, hails, or a combination of these.

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Cloud formation

• There are 3 main types of clouds
• Cirrus- high clouds- wispy and feathery looking.
  Composed of ice
• Cumulus- puffy clouds- usually form when warm air
  is forced upward.
• Stratus- layered- form where warm and cool air
  meet.

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Weather

• Weather patterns result from global patterns of
  wind and pressure.
• Global winds are caused by the heating and
  cooling of air.
• The most important to the US are the westerlies
  (winds from the west) and the trade winds (winds
  from the east).

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• Westerlies bring weather from the Pacific side to
  the Atlantic side.
• Trade winds move hurricane systems from east to
  west.
• As part of these winds, high speed jet streams
  control much of the storm movement.

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High and Low Pressure

• Earths heating controls the pressure.
• The areas of low pressure have a rainy climate,
  like the equator.
• Areas of high pressure have dry climates like
  deserts.

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Air Masses and Fronts

• There are large masses of air above the land and
  the water.
• North American Air Masses
• These masses meet along front lines.
• Each type of front has different weather patterns
  associated with it.

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Types of Fronts

• Cold- cold air pushes warm air up violently-
  Causes severe weather.

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• Warm front- warm air advances and gently moves
  over cold air- causes rain showers

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• Stationary- neither warm nor cold push past each
  other. Causes heavy rains.

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• Occluded- Where 2 cold air masses meet with warm
  air above. Causes rain.

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Tornadoes
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Climate

• Climate means the long-term average of weather
  conditionswind, temperature, precipitation,
  moisture, and other aspects of weather.

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Causes of Climate

• Latitude- distance from the equator helps
  determine temperature and amount of light
• Temperature- average temp determines the types of
  plants that can survive
• Distance from ocean- the closer to the water the
  more constant the climate. Affected by global
  winds

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• Precipitation- determines types of plants.
  Highest amounts at equator.
• Mountains- most rain on side of the mountain that
  faces the wind. Air rises, cools and rains on
  that side.

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Types of climates

• Three major types cold, semi-arid (dry), and arid

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Climate Changes

• Cycles of glaciations, called ice ages, represent
  long-term climatic change
• Last ice age-18,000-22,000 years ago
• Changes in Earths orbit are the most important
  factors, producing changes that determine the
  rhythmic cycles of glaciation.

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Human Influences

• Humans may be speeding up the process by
  releasing pollution that changes the climate
  faster than the cycle.
• The excess carbon is from burning fossil fuels
  and removing vegetation.
• Other gases like methane and nitrogen oxides are
  also released by humans.

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Affects of human activities

• Global warming- proposed theory that humans are
  increasing the natural rate of temperature
  change. Main cause carbon dioxide.
• Ozone thinning- pollutants that destroyed ozone.
  These pollutants are now banned and the ozone
  layer is slowly recovering.

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