The Atmosphere

The Atmosphere

1. The Air Around You

   • Composition of the Atmosphere
     • Nitrogen
       • Nitrogen is the most abundant amount of gas in the atmosphere.  The gas moves in a cycle from the air to the soil, into living things, and then back into the air.
     • Oxygen
       • Oxygen is the second most abundant gas in the atmosphere, but only makes up less than one fourth of the volume. Oxygen is needed for our existence, in which we need it to breathe. Most Oxygen has two oxygen molecules, but a type called Ozone has three atoms.
     • Other
       • Carbon Dioxide is also essential for life. Plants take in carbon dioxide from the air to produce energy, they give off carbon dioxide as a waste product. Water vapor is water in gaseous form, where it is in the atmosphere and the amount of vapor in the air varies from place to place.  
   • Importance of the Atmosphere
     • Earth's Atmosphere contains water, warmth, oxygen and carbon dioxide, which are all things we need to survive. The atmosphere also protects us from most meteoroids and radiation from the sun.
   • Air Quality
     • Smog and Acid Rain
       • The burning of fossil fuels can cause smog and acid rain. Photochemical smog is the brown haze that develops in sunny cities. acid rain is rain that is more acidic than usual.
     • Sources of Polution
       • Pollutants are harmful substances in the air, water, lr soil.  Air that contains harmful particles and gases is said to be polluted. Air pollution can affect the health of humans and other living things.
       • Some pollution occurs naturally, such as forest fires, soil erosion, and dust storms release a great molds and pollen.  However we also cause pollution by the burning of fossil fuels.
   • Improving Air Quality
     • To save the atmosphere, the United States passed a number of laws and regulations to reduce air pollution. However, making a change will be difficult.

2. Air pressure

   • Properties of Air
     • Density
       • Density is the amount of mass in a given volume of air.
     • Pressure
       • Pressure is the force pushing on an area or surface. Air pressure is the result of the weight of a column of air pushing down on an area.
       • The air pushing down on top of your desk is balanced by the air pushing up on the bottom of your desk.
   • Altitude and the Properties of Air
     • Altitude ,or elevation, is the distance above sea level, the average level of the surface of the oceans.
     • Altitude Affects Air Pressure
       • The higher you are, the less air pressure.
     • Altitude Also Affects Density
       • The higher you are, the density
   • Measuring Air Pressure
     • Mercury Barometeres
       • A mercury barometer consists of a glass tube open at the bottom end and partially filled with mercury.
       • The mercury barometer works in which mercury the is placed in the tube on top of a plate. The more pressure there is, more mercury will be pushed through the tube.
     • Aneroid Barometers
       • An Aneroid barometer has an airtight metal chamber, in which the metal chambers are sensitive to changes in air pressure. When air pressure increases, the thin walls of the chamber are pushed in.
     • Units of Air Pressure
       • Air pressure is measured in millibars

3. Layers of the Atmosphere

   • The Stratosphere
     • The stratosphere extends from the top of the troposphere to about 50 kilometers above Earth's surface. The ozone layer in the stratosphere absorbs ultraviolet radiation.
   • The Thermosphere
     •  The thermosphere extends from 80 kilometers above Earth's surface outward into space. It has no definite outer limit, but blends gradually with outer space.
     • Temperature is the average amount of energy of motion of each molecule of a substance. ionosphere is the lower layer of the thermosphere. The exosphere is the outer portion of the thermosphere. The exosphere extends from about 400 kilometers outward. for thousands of kilometers.
   • The Mesosphere
     • The mesosphere is above the stratosphere and the middle layer of Earth's atmosphere. Most meteoroids burn up in the mesosphere, producing meteor trails.
   • Troposphere
     • The troposphere is the inner, or lowest, layer of Earth's atmosphere. Rain, snow, storms, and most clouds occur in the troposphere.

4. Energy in Earth's Atmosphere

   • Energy in the Atmosphere
     • Scattering is dust particles and gases in the atmosphere reflect light in all directions.  The sky seems blue because the light you see has been scattered by gas molecules n the atmosphere.
     • More light from the blue end of he spectrum is removed by scattering before it reaches your eyes.
   • Energy From the Sun
     • Visible Light
       • Visible light includes all of the colors that you see in a rainbow. The different colors are the result of different wavelengths.
     • Non-Visible Radiation
       • Infrared radiation is a form of electromagnetic energy and has wavelengths no longer than red light. Ultraviolet radiation is an invisible form of energy with wavelengths that are shorter than violet light. This type of radiation can also cause sunburns.
   • Energy at Earth's Surface
     • The greenhouse effect is the process by which gases hold heat in the air. The greenhouse effect is a natural process that keeps Earth's atmosphere at a temperature that is comfortable for most living things.

5. Heat Transfer in the Atmosphere

   • How Heat is Transferred
     • Heat is the transfer of thermal energy from a hotter object to a cooler one.
     • 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. Conduction works well in some solids, such as metals, but ot as well in liquids and gases.
     • Convection
       • Convection is teh transfer of heat by the movement of a fluid.
     • Heating the Troposphere
       • Convection currents is the upward movement of warm air and the downward movement of cool air.
   • Thermal Energy and Temperature
     • thermal energy is the total energy of motion in the particles of a substance.
     • Measuring Temperatures
       • A thermometer is a thing glass tube with a bulb on the end that contains liquid, usually colored alcohol. Temperature is one of the most important factors affecting the weather.
     • Temperature Scales
       • Temperature is measured in units called degrees.

6. Winds

   • Local Winds
     • Local winds are winds that blow over short distances. Local winds are caused by the unequal heating of Earth's surface withing a small area.
     • Sea Breeze
       • A sea breeze or a lake breeze is a local wind that blows from an ocean or lake.
       • as the sun heats Earth's surface during the day, the land warms up faster than the water. As a result, the air over land rises and expands, creating a low pressure area. Cool air blows inland from over the water and moves underneath the warm air, causing a sea breeze.
     • Land Breeze
       • A land breeze is the flow of air from land to a body of water.
       • A night, land cools more quickly than water, so the air over the land becomes cooler than the air over the water. As the warmer air over the water expands and rises, cooler air from the land moves beneath it.
   • Global Winds
     • Global winds are winds that blow steadily from specific directions over long distances.
     • Global Convection Currents
       • Temperature differences between the equator and the poles produce giant convection currents in the atmosphere.
       • Because the equator is a place with almost direct sunlight, warm air rises and sinks at the poles. Therefore, air pressure is lower near the equator. As a result, winds from the poles blow toward the equator while  higher in the atmosphere, air flows away from the equator toward the poles. This causes global winds.
     • The Coriolis Effect
       • The Coriolis effect is the way Earth's rotation makes winds curve.
       • If Earth did not rotate, global winds could blow in a straight line from the poles toward the equator. Because Earth is rotating, however, global winds do not follow a straight path. As the winds blow, Earth rotates from west to east underneath them, making it seem as if the winds have curved.
   • What is Wind
     • Wind is the horizontal movement of air from an area of high pressure to an area of lower pressure.
     • Wind Chill Factor
       • The wind chill factor is the increased cooling a wind can cause. 
     • Measuring Wind
       • An anemometer is a measuring tool for wind speed, in which it has three or four cups mounted at the ends of spokes that spin on an axle. The force of the wind against the cups turns the axle. A meter on the axle shows the wind speed
   • Global Wind Belts
     • Horse Latitudes
       • Latitude is distance from the equator, measured in degrees.
       • At about 30 degrees north and south latitudes, the air stops moving toward the poles and sinks. In each of these regions, another belt of calm air forms.
     • Doldrums
       • Doldrums are a calm area where warm air rises.
       • Near the equator, warm air rises and flows to the poles, creating a low pressure area. Cool air moves into the vicinity, but rises before it moves very far. There is little horizontal movement, so places near the equator have little or no wind. These places are called the doldrums.
     • Trade Winds
       • When the cold air from the horse latitudes sink, the create a place with high pressure. This high pressure causes winds to blow both toward and away from the equator.
       • The wind that blows toward the equator are turned west by the Coriolis effect. As a result, winds in the Northern Hemisphere between 30 degrees north latitude and the equator generally blow from the northeast. Same thing applies in the Southern Hemisphere.
     • Prevailing Westerlies
       • Between 30 degrees and 60 degrees north and south, winds that blow toward the poles are turned toward the east by the Coriolis effect. These are called the prevailing westerlies. Prevailing westerlies play a big role in the weather of the United States.
     • Polar Easterlies
       • Cold air from the poles sink back toward lower latitudes. The Coriolis effect also shifts these winds to the west, producing the polar easterlies. The polar easterlies meet with the prevailing westerlies, causing a big impact of weather in the United States
     • Jet Streams
       • Jet streams are bands of high speed winds.
       • These winds are hundreds of kilometers wide but only a few kilometers deep. Jet streams generally blow from west to east. As jet streams travel around Earth, they wander north and south along a wavy path.