Weather Factors

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Weather Factors

• Chapter 16

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15.1The Air Around You

• Earth's Atmosphere isA mixture of gases with
  some suspended solids and liquids.
                   
• Three common solids in atmosphere
• Ice
• Dust
• Salt - from ocean spray
• Gas Composition of Earth's atmosphere
• Nitrogen -78 of atmosphere
• Oxygen - 21 of atmosphere
• Trace gases -1 - Carbon Dioxide , Argon, Neon,
  Helium, Hydrogen, Methane

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15.2 Air Pressure

• Air consists of atoms molecules therefore air
  has mass
• Because it has mass it also has Density
• Density Mass/Volume
• Pressure weight of air pressing down on you is
  the same as a school bus BUT air is pushing in
  all directions so it balances out
• Measure by a barometer
• Mercury Barometer liquid mercury
• Aneroid Barometer without liquid

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Altitude or Elevation

• Distance above sea level
• Air Pressure decreases as Altitude Increases thus
  so does density
• Molecules are spaced out
  more thus it is more difficult to breath

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15.3 Layers of the Atmosphere

• 5 layers
• 1. Troposphere area closest to the ground,
  75of the gases, dust, ice and liquid
  water-Weather, Clouds, and smog occur here
• 2. Stratosphere Ozone layer
• 3. Mesosphere
• 4. Thermosphere contains the ionosphere where
  electrical charged particles are (get AM radio at
  night when sun goes down, particles quit jumping)
• 5. Exosphere upper most portion

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Earths Atmosphere and its Energy

• Energy comes from the sun in the form of
  Electromagnetic Waves

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Energy Transfer occurs by

• Radiation electromagnetic waves, no contact but
  still feel it, moves from object with a higher
  temperature to one with a lower temperature
• Conduction direct contact, fast moving
  molecules to slow moving molecules
• Convection density differences, air is warmed,
  the air molecules move apart which increases the
  volume of air which reduces its density thus the
  air raises and causes a circular movement of air
  called a convection current

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Movement of Air

• Earths surface is curved rather than flat, air
  equator is heated more than any other place on
  Earth
• Coriolis Effect caused by Earths rotation, air
  masses moving south in the Northern Hemisphere
  are turned
• westward (because
• Earth is moving to the
• east)

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Wind Systems

• Doldrums windless zone at the equator
• Trade Winds 15o North or South of the equator
  blow to the southwest (NH)/northwest (SH)
• Prevailing Westerlies 30o and 60o North and
  South winds blow in the opposite direction as the
  trade winds SW to NE in NH and in SH NW to SE
• Polar Easterlies NE to SW near the North Pole
  and from the SE to the NW in the SH
• Jet Streams winds near top of troposphere
• Sea and Land Breezes convection current where
  land meets the sea (sea/day land/night)

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Factors of Weather

• Humidity amount of water vapor in the air
• (cooler air, slower, condenses rains
• Hot air, faster, air holds more moisture
• Relative humidity amount of water vapor in air
  as a percentage of amount it can hold
• Saturated air 100 relative humidity
• Dew Point temperature at which it condenses
• Clouds formed when the humid air is cooled to its
  dew point and condenses
• Fog- is a stratus cloud close to the ground
• Precipitation occurs when water droplets reach
  .2 mm

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Weather Patterns

• Air mass large body of air that has the same
  properties as the surface over which it develops
• Fronts boundary between 2 air masses as they
  collide
• Warm Front warm air mass slides under cold air
  mass (less dense) High cirrus clouds,
• Cold Front cold air invades cold, cumulus
  clouds and rain
• Stationary Front pressure differences and it
  doesnt move lights winds and rains
• Occluded Front 2 cool air masses forces warm
  air up, heavy precipitation and wind
• Precipitation from warm air being cooled