The Atmosphere

The Atmosphere

1. Section 1: The air Around You (Pg. 256)

   • Composition of the Atmosphere
     • Nitrogen
       • -Nitrogen is the most common gas in the atmosphere. -Nitrogen moves in a cycle from the air to the soil, into living things, then back into the air.
     • Oxygen
       • -Oxygen is the second most abundant gas in the atmosphere, but it makes up less than one fourth of the volume. -Most oxygen molecules have two oxygen atoms.
     • Carbon Dioxide
       • -Each molecule of carbon dioxide has one atom of carbon and two atoms of oxygen. -When plant and animal cells break down food to produce energy, they give off carbon dioxide as waste product.
     • Other gases
       • -Oxygen and nitrogen together make up 99% of dry air.  -The remaining gases are called trace gases because only small amounts of them are present.
     • Water vapor
       • -Water vapor is water in the form of gas. -The amount of water vapor in the air varies greatly from place to place and from time to time.
     • Particles
       • -Pure air contains only gases. -The air we breathe also contains tiny solid and liquid particles of dust, smoke, salt, and other chemicals.
   • Importance of the Atmosphere
     • -Earth's atmosphere makes conditions on Earth suitable for living things. -The atmosphere contains oxygen and other gases that living things need to survive. -The atmosphere is constantly changing, with gases such as nitrogen, oxygen, and carbon dioxide moving in and out of living things, the land, and the water.
   • Air Quality
     • Sources of Pollution
       • -Some pollution occurs naturally. -Forest fires, soil erosion, and dust storms release a great deal of smoke and dust into the air. -The wind carries particles of molds and pollen. 
     • Smog and Acid Rain
       • -The burning of fossil fuels can cause smog and acid rain. -The brown haze that develops in sunny cities is called photochemical smog. -Rain is slightly naturally acidic, but rain that contains more acid than normal is known as acid rain.
   • Improving Air Quality
     • -The federal and state governments have passed a number of laws and regulations to reduce air pollution.  -Recently-built power plants are less polluting than power plants that have been in operation for many years.

2. Section 2: Air Pressure (Pg. 262)

   • Properties of Air
     • Density
       • -The amount of mass in a given volume of air is its density. -If there are more molecules in a given volume, the density is greater. If there are fewer, the density is less.
     • Pressure
       • -The force pushing on an area or surface is known as pressure. -Air pressure is the result of weight of a column of air pushing down on an area.
   • Measuring Air Pressure
     • Mercury Barometers
       • -A mercury barometer consists of a glass tube open at the bottom end and partially filled with mercury. -Greater air pressure forces the column of mercury higher.
     • Aneriod Barometers
       • -An aneriod barometer has an airtight metal chamber . -The metal chamber is sensitive to changes in air pressure.
     • Units of Air Pressure
       • -Most weather reports for the general public use inches of mercury. -One inch of mercury is approximately 33.87 milibars, so inches of mercury is approximately equal to 1,016 milibars. 
   • Altitude and the Properties of Air
     • Altitude Affects Air Pressure
       • -Air at sea level is like the bottom book of a stack of books. -Sea level air has the weight of the whole atmosphere pressing on it. -Air near the top of the atmosphere has less weight pressing on it, and thus has lower air pressure.
     • Altitude also Affects Density
       • -As you go up through the atmosphere, the density of the air decreases.

3. Section 3: Layers of the Atmosphere (Pg. 267)

   • The Troposhere
     • -We live in the inner, or lowest, layer of Earth's atmosphere, the troposphere. -The troposphere is the layer of the atmosphere in which Earth's weather occurs.
   • The Stratosphere
     • -The stratosphere extends from the top of the troposphere to the to about 50 kilometers above Earth's surface.  -The stratosphere is the second layer of the atmosphere and contains the ozone layer.
   • The Mesosphere
     • -Above the stratosphere, a drop in temperature marks the beginning of the next layer, the mesosphere. -The mesosphere is the layer of the atmosphere that protects earth's surface from being hit by most meteoriods.
   • The Thermosphere
     • -Near the top of the atmosphere, the air is very thin.  -The outermost layer of Earth's atmosphere is the thermosphere.

4. Section 4: Energy in Earth's Atmosphere (272)

   • Energy from the Sun
     • Visible Light
       • -Visible light includes all of the colors that you can see in a rainbow: red, orange, yellow, green, blue, indigo, and violet.
     • Non-visible Radiation
       • -One form of electromagnetic energy, infrared radiation, has wavelengths that are longer than red light. -The sun also gives off ultraviolet radiation, which is an invisible form of energy with wavelengths that are shorter than violet light.
   • Energy in the Atmosphere
     • -Some sunlight is absorbed or reflected by the atmosphere before it can reach the surface. The rest passes through the atmosphere to the surface. -Dust particles and gases in the atmosphere reflect light in all directions, through a process called scattering. 
   • 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: Heat Transfer in the Air (Pg. 278)

   • Thermal Energy and Temperature
     • -The total energy of motion in the particles of a substance is called thermal energy.
     • Temperature Scales
       • -Temperature is measured in units called degrees. -Celsius scale and the Fahrenheit scale are commonly used.
     • Measuring Temperature
       • -Air temperature is usually measured with a thermometer. -A thermometer is a glass tube thin glass tube with a bulb on one end that contains a liquid, usually colored alcohol.
   • How Heat is Transferred
     • Radiation
       • -The direct transfer of energy by electromagnet waves.
     • Convection
       • -The transfer of heat by the movement of a fluid is called convection.
     • Conduction
       • -The direct transfer of heat from one substance to another that is touching is called conduction.
     • Heating the Troposphere
       • -Within the troposphere, heat is transferred mostly by convection.

6. Section 6: Winds (Pg. 282)

   • What is Wind?
     • Measuring Wind
       • -Wind speed can be measured with an anemometer.
     • Wind-Chill Factor
       • -The increased cooling a wind can cause is called the wind-chill factor.
   • Local Winds
     • 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
     • Global Convection Currents
       • -Temperature differences between the equator and the poles produce giant convection currents in the atmosphere.
     • The Coriolis Effect
       • -The way Earth's rotation makes winds curve is called the Coriolis effect.
   • Global Wind Belts
     • 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. -Latitudes 30 degrees north and south of the equator came to be called the horse latitudes.
     • Trade Winds
       • -For hundreds of years, sailors relied on these winds to move ships carrying valuable cargoes from the West Indies and South America.
     • Prevailing Westerlies
       • -The prevailing westerlies blow generally from the southwest in north latitudes and from the northwest in south latitudes.