Weather - Chapter 1

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Weather - Chapter 1

• The Atmosphere

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What is weather?

• Refers to the state of the atmosphere at a
  specific time and place.
• The one thing that you can talk to anybody
  about!
• If you dont like the weather just wait around
  it will change!

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1.1 The Air Around You

• Weather is constantly changing
• The atmosphere is the envelope of gases that
  surrounds the planet

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• Composition of the atmosphere
• NITROGEN (N2) 78
• OXYGEN (O2) 21
• Other 1
• CARBON DIOXIDE
• WATER VAPOR
• METHANE
• ARGON
• PARTICLES (dust, smoke, salt, chemicals)

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Atmosphere Characteristics
Water vapor is the source of all clouds and
precipitation. Like carbon dioxide, water vapor
absorbs heat given off by Earth. It also absorbs
some solar energy.
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• Ozone is a form of oxygen that combines three
  oxygen atoms into each molecule (O3).
• If ozone did not filter most UV radiation and all
  of the suns UV rays reached the surface of
  Earth, our planet would be uninhabitable for many
  living organisms.
• It forms when lightening interacts with oxygen in
  the air.

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1.2 Air Pressure

• Properties of Air
• Because air has MASS, it also has other
  properties, including DENSITY and PRESSURE.
• Density
• D M/V
• Pressure- the force pushing on an area or
  surface.
• Air Pressure- The result of the WEIGHT OF A
  COLUMN OF AIR PUSHING DOWN on an area.
• Air pressure changes from day to day. Denser air
  exerts more pressure than less dense air.

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• Measuring Air Pressure
• Barometer
• an instrument that is used to MEASURE AIR
  PRESSURE.
• Two common kinds
• 1. MERCURY Barometers-glass tube open at the
  bottom end and partially filled with mercury
• Mercury is pushed higher with more air pressure.

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• 2. ANEROID Barometers-air tight metal chamber
  that is sensitive to changes in pressure.
• METAL SPRING AND DIAL
• Fig 6, page 13

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Measuring air pressure - units

• Several different units used
• Most use inches of mercury (Hg)
• Based on the height of the column of Hg in a Hg
  barometer. 30 inches of mercury
• National Weather Service indicates pressure as
  millibars
• 1 inch of Hg 33.87 millibars
• eg. 30 in Hg 33.87 millibars 1,016
  millibars
• 1 in of Hg
• Hectopascal (symbol hPa) is a SI unit, one
  millibar is equivalent to 100 pascals or one
  hectopascal. 1mb 1hPa

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Altitude and Air Pressure

• Altitude and properties of Air
• Altitude ELEVATION OR DISTANCE ABOVE SEA LEVEL
• Altitude and Air Pressure/Density
• INVERSELY PROPORTIONAL
• Increase in ALTITUDE Decrease in air PRESSURE,
  LESS air pushing down from above you.

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Altitude and Density

• The density of air decreases as altitude
  increases. Air at sea level has more gas
  molecules in each cubic meter than air at the top
  of a mountain.

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Graphic Organizer
Air Pressure
measured with
measured in units of
decreases as
Inches of mercury
Millibars
Barometers
Altitude
Density decreases
include
increases
Mercury
Aneroid
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1.3 Layers of the Atmosphere
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Layers of the atmosphere

• There are 4 layers in the atmosphere classified
  according to temperature changes.
• They are the troposphere, stratosphere,
  mesosphere, and the thermosphere.

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Troposphere

• This is the layer that is closest to the surface
  of the earth
• Its elevation ranges from 0 to 12 km
• Weather only occurs here

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Stratosphere

• This layer sits on top of the troposphere
• Its elevation ranges from 12 km to around 50 km
• This layer contains the ozone layer, which
  protects the earth from ultraviolet radiation
  from the sun.

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Mesosphere

• This layer is above the stratosphere
• Its elevation ranges from 50 to 80 km
• This layer protects the earth from getting hit
  from asteroids

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Thermosphere

• This is the highest layer of the atmosphere
• Its height ranges from 80 to 400 km
• This is where most small meteorites burn up and
  is also the location in the atmosphere that the
  northern lights occur (aurora borealis)
• It is divided into the ionosphere (lower layer)
  and exosphere (upper layer)

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Changing Temperatures

• The graph shows how temperatures in the
  atmosphere change with altitude.
• Use it to answer the questions that follow.

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Changing Temperatures
What two variables are being graphed? In what
unit is each measured?
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Changing Temperatures

• Temperature and
• altitude degrees Celsius and kilometers

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Graph Analysis

• What is the temperature at the bottom of the
  stratosphere?
• Which layer of the atmosphere has thelowest
  temperature?
• Describe how temperature changes as altitude
  increases in the troposphere.

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1.4 Air Quality

• Pollutants- harmful substances in the air, water
  and soil
• They can affect human health and other things

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Sources of Pollution

• Natural sources- forest fires, soil erosion and
  dust storms. Wind carries particles of mold and
  pollen. Volcanoes emit clouds of gas, dust, and
  ash.
• Human activities- farming, construction, burning
  of fossil fuels (coal, oil, gas, diesel fuel)
• Fossil fuels produce a variety of pollutants
  including carbon monoxide, nitrogen oxides and
  sulfur oxides

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Smog and Acid Rain

• Burning of fossil fuels can cause smog and acid
  rain
• London-Type Smog- created when particles in coal
  smoke combine with water droplets in humid air
• Photochemical Smog- brown haze formed by the
  action of sunlight on pollutants such as
  hydrocarbons and nitrogen oxides. This is a
  combination of ozone and other pollutants.

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• Acid Rain- forms when nitrogen oxides and sulfur
  oxides combine with water to form nitric acid and
  sulfuric acid.
• Rain, sleet, snow, fog and dry particles can
  carry these acids to trees and lakes.
• It can damage buildings and statues and can make
  water inhabitable for plants and organism.

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Before and After
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Effects of Pollution

• Air pollution can cause many different problems.
  This table shows the health effects of air
  pollution. Pollen also can cause difficulties for
  people with allergies.

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Improving Air Quality

• The Environmental Protection Agency (EPA)
  monitors air pollutants in the United States.
• New model cars and power plants produce fewer
  pollutants than older models.
• Cities are still polluted because there are more
  power plants and cars with the increase in
  population.
• Reducing pollution can be very expensive.