Chapter 17: The Atmosphere

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Chapter 17 The Atmosphere

• Weather - the state of the atmosphere at any
  given time and place.
• Weather is constantly changing.
• Climate - is weather over a long period of time,
  describes regions.

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Measure Of Weather

• 1. Temperature
• 2. Humidity
• 3. Precipitation Type
• 4. Precipitation Amount
• 5. Air Pressure
• 6. Wind Speed
• 7. Wind Direction

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Atmosphere Composition

• Different today than long time ago!How?
• 2 main gases make up 99
• Nitrogen - 78 Oxygen - 21
• Carbon Dioxide - small amount/important
• Water (vapor)- amount varies
• Both absorb heat given off by Earth

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• Dust particles are important - allow water
  droplets to form around them so we can have
  precipitation.
• Ozone O3 - found in stratosphere
• - protects us from UV radiation
• - we harm ozone by using CFCs aerosols, AC,
  fridges, etc.
• - Ozone hole in 85

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Height Structure

• The atmosphere rapidly thins as you go away from
  Earth.
• Pressure reduces as you go up.
• At sea level air pressure is about 14.7 lbs per
  square inch.
• Generally speaking temperatures cool as you go
  up!

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4 atmospheric layers

• Thermosphere - top layer,auroras, boundary to
  space, very thin amount of gases,
  temps. Increase as you go up
• Mesosphere - next layer down, meteors hopefully
  burn up here, coldest layer, temperatures get
  colder as you go up.

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• Stratosphere - contains ozone layer, temperatures
  increase as you go up.
• Troposphere - closest layer to Earth, contains
  all weather, temperatures decrease as you go up.

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Earth-Sun relationships

• Solar energy is not evenly distributed.
• (latitude, time of day, season)
• Earth has 2 principle motions
• 1.Rotation - spinning, causes night day,
• 24 hours (23 hrs 56 mins.)
• 2.Revolution - orbiting, gives us year
• 365.25 days

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Earths Orientation

• Seasonal changes occur because Earths position
  to the sun changes.
• Earths 23.5 degree tilt gives us seasons
• No tilt would mean NO seasons!
• Read page 481!

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4 SEASONS

• Summer and Winter
• Solstice means sun stop
• - summer solstice June 21stlongest day
• - sun over the Tropic of Cancer
• - winter solstice Dec. 21stshortest day
• - sun over the Tropic of Capricorn

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Equinoxes

• Equinox mean equal night day
• - spring equinox March 21st12 hr sun
• - autumnal equinox Sept. 21st12 hr
  sun
• - sun over the equator for both of these

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17.2 Heating the Atmosphere

• Heat energy transferred from one object to
  another
• Temperature a measure of how fast the molecules
  are moving
• Hotter moves faster, colder
• Heat is transferred 3 ways
• Conduction
• Convection
• Radiation

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1. Conduction

• Heat transfer through touching
• Touching a hot stove
• Sticking your hands in the snow

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2. Convection

• Heat transfer from moving particles, like air
  and/or water.
• Cold water in the lake
• Hot water moving around in a pot on the stove

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3. Radiation

• Heat transfer by waves
• Heat from the sun
• Heat from a stove burner or fireplace
• Electromagnetic waves (EM)
• These are the waves from the sun
• There are types of light we cannot see such as
  ultraviolet (UV), microwaves, infrared/heat waves
  (IR), x-rays

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What Happens to Solar Radiation?

• Some is absorbed by the object
• Some passes through the object
• Some bounces off the object
• Reflection happens when light bounces off an
  object

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• From the sun
• 50 is absorbed by earth
• 20 is absorbed by clouds and atmosphere
• 30 is reflected back to space

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Greenhouse Effect

• 1. Light from the sun hits Earth
• 2. Earth warms up and releases heat
• 3. The CO2 and H2O trap the heat like a
  blanket
• 4. Too much CO2 makes Earth too hot

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17.3 Temperature Controls

• Temperature control any factor that causes
  temps to vary from place to place.
• Latitude distance from equator
• Land or water nearby land heats up faster and
  to a higher temperature. Water thats nearby
  makes it less extreme.

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• 3. Geographic position where you are makes a
  difference
• 4. Altitude it gets colder as you get higher
  into the atmosphere.
• 5. Cloud cover clouds keep it cooler in the
  day, but warmer at night!
• Clouds reflect outgoing heat and/or radiation
  back to the earth

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• Albedo how reflective a surface is. A high
  albedo reflects a lot of light.
• Bright materials (snow) have a high albedo, so
  reflect heat/energy/light
• Dark colored objects have a low albedo (pavement,
  grass) so they absorb light/energy/heat.