The Atmosphere

The Atmosphere

1. Section 1 pg.256 : The Air Around You

   • Composition of the Atmosphere
     • Nitrogen
       • Nitrogen is the most common gas in the atmosphere, and it makes up a little more than three fourths of the air we breathe.
     • Oxygen
       • Even though oxygen is the second most abundant gas in the atmosphere, it makes up less than one fourth of the volume. Ozone is a form of oxygen that has three oxygen atoms in each molecule.
     • Carbon Dioxide
       • Each molecule of carbon dioxide, which is essential to life, has one atom of carbon and two atoms of oxygen.
     • Other Gases
       • The remaining gases in the atmosphere are called trace gases because only small amounts of them are present.
     • Water Vapor
       • In reality, air is not dry because it contains water vapor, water in the form of gas.
     • Particles
       • The air we breathe also contains tiny solid and liquid particles of dust, smoke, salt, and other chemicals.
   • Importance of Atmosphere
     • Earth's atmosphere makes conditions on Earth suitable for living things. It provides air and protection as well as many other benefits.
   • Air Quality
     • Sources of Pollution
       • Most air pollution is the result of burning fossil fuels, wuch as coal, oil, gasoline, and diesel fuel.
     • Smog and Acid Rain
       • The burning of fossil fuels can cause smog and acid rain. Photochemical smog is brown haze that is a type of air pollution. Acid rain is rain that is more acidic than usual.
   • Improving Air Quality
     • In the United States, the federal and state governments have passed a number of laws and regulations to reduce air pollution.

2. Section 2 pg.262 : Air Pressure

   • Properties of Air
     • Density
       • You can calculate the density, the given volume of air, of a substance by dividing its mass by its volume.
     • Pressure
       • Air pressure is the result of the weight of a column of air pushing down on an area. The column of air extends upward through the entire atmosphere.
   • Measuring Air Pressure
     • Mercury Barometers
       • A mercury barometer consists of a glass tube open at the bottom end and partially filled with mercury. At seal level the mercury column is about 76 centimeters high, on average.
     • Aneroid Barometerw
       • An aneroid barometer has an airtight metal chamber, which is sensitive to all changes in air pressure.
     • Units of Air Pressure
       • Weather reports mostly use inches of mercury as an unit of air pressure. Another unit of air pressure is millibars.
   • Altitude and the Properties of Air
     • Altitude Affects Air Pressure
       • Air pressure is greater at sea level and decreases as the altitude increases.
     • Altitude Also Affects Density
       • As you go up through the atmosphere, the density of the air decreases.

3. Section 3 pg.267 : Layers of the Atmoshpere

   • The Troposphere
     • You live in the inner, or lowest, layer of Earth's atmosphere, the troposphere, where Earth's weather occurs
   • The Stratosphere
     • The stratosphere is the second layer of the atmosphere and contains the ozone layer, which protects Earth from the ultraviolet rays from the sun. The upper stratosphere is warmer than the lower stratosphere.
   • The Mesosphere
     • The mesosphere is the layer of the atmosphere that protects Earth's surface from being hit by most meteoroids.
   • The Thermosphere
     • The outermost  layer of Earth's atmosphere is the thermosphere, which extends 80 kilometers above Earth's surface outward into space. The thermosphere is divided into two layers called the ionosphere and exosphere.

4. Section 4 pg.272 : Energy in Earth's Atmosphere

   • Energy From the Sun
     • Visible Light
       • Visible light includes all of the colors that you see in a rainbow. Red and orange have the longest wavelengths while blue and violet have the shortest.
     • Non-Visible Radiation
       • Infrared radiation have wavelengths longer than red and orange light. Ultraviolet radiation have shorter wavelengths than blue and violet.
   • Energy in the Atmosphere
     • Some sunlight is absorbed or reflected by the atmosphere before it can reach the surface. The rest passes trough the atmosphere to the surface. Dust particles and gases in the atmosphere reflect light in all directions, a process called scattering, which has more effects on light with shorter wavelengths.
   • Energy at Earth's Surface
     • When Earth's surface is heated, it radiates most of the energy back into the atmosphere as infrared radiation. The process by which gases hold heat in the air is called the greenhouse effect.

5. Section 5 pg.278 : Heat Transfer in the Atmosphere

   • Thermal Energy and Temperature
     • Measuring Temperature
       • Air temperature is usually measured with a thermometer. A thermometer is a thin glass tube with a bulb on one end that contains a liquid, usually colored alcohol. A thermometer works because liquids expand when they are heated and contract when they are cooled.
     • Temperature Scales
       • Temperature is measured in units called degrees. When using the Celsius scale, freezing point of pure water is 0 degrees and boiling point of pure water is 100 degrees. When using the Fahrenheit scale, the freezing point of water is 32 degrees and boiling point is 212 degrees.
   • How Heat is Transferred
     • Heat is transferred in three ways within the atmosphere: radiation, conduction, and convection.
     • Radiation
       • Radiation is the direct transfer of energy by electromagnetic waves.
     • Conduction
       • The direct transfer of heat from one substance to another substance that it is touching is called conduction.
     • Convection
       • The transfer of heat by the movement of a fluid is called convection.
     • Heating the Troposphere
       • In the troposphere, heat is transferred mostly by convection currents. Convection currents are when less dense hot air rises than cools and begin to drop again.

6. Section 6 pg.282 : Winds

   • What is Wind?
     • Winds are caused in differences of air pressure.
     • Measuring Wind
       • Wind speed can be measured with an anemometer, an instrument that has three or four cups mounted at the ends of spokes that spin on an axle.
     • Wind-Chill Factor
       • The increased cooling of a wind can cause is called the wind-chill factor.
   • Local Winds
     • Local winds are caused by the unequal heating of Earth's Surface within a small area.
     • Sea Breeze
       • A sea breeze or a lake breeze is a local wind that blows from an ocean or lake.
     • Land Breeze
       • The flow of air from land to a body of water is called a land breeze.
   • Global Winds
     • Like local winds, global winds are created by the unequal heating of Earth's surface. But unlke local winds, global winds occur over a large area.
     • Global Convection Currents
       • Temperature differences between the equator and the poles produce giant convection currents in the atmosphere. Warm air rises at the equator, and cold air sinks at the poles.
     • The Coriolis Effect
       • The way Earth's rotation makes wind curve is called the Coriolis effect.
   • Global Wind Belts
     • The major global wind belts are the trade winds, the polar, easterlies, and the prevailing westerlies.                                                                      
     • Doldrums
       • Regions near the equator with little or no wind are called the doldrums.
     • Horse Latitudes
       • Latitude is distance from the equator, measured in degrees. Horse Latitudes are calm areas of falling air.
     • Trade Winds
       • Trade winds are winds are turned west by the Coriolis effect, so they blow from the horse latitudes toward the equator. For hundreds of years, sailors relied on these winds to carry their trading ships.
     • Prevailing Westerlies
       • Prevailing Westerlies blow away from the horse latitudes after they are turned east by the Coriolis effect.
     • Polar Easterlies
       • Polar Easterlies blow cold air away from the poles. When the polar easterlies and prevailing westerlies meet at about 6o degrees north and 60 degrees south latitudes, along a region called the polar front, this majorly effects they weather in the U.S.
     • Jet Streams
       • About 10 kilometers above Earth's surface are bands of high-speed winds called jet streams.