The Atmosphere

The Atmosphere

1. The Air Around You

   • Composition of the Atmosphere
     • Nitrogen
       • Nitrogen is the most common gas in the atmosphere. It makes up more that 3/4 of the air we breathe.
     • Oxygen
       • Even though oxygen is the second most abundant gas in the atmosphere, it makes up less than 1/4 of the volume.
     • Carbon Dioxide
       • Plants take in carbon dioxide from the air to make food. humans and animals release carbon dioxide as a waste product.
     • Other Gases
       • Argon and carbon dioxide make up most of the other 1% of air in the atmosphere.
     • Water Vapor
       • Water vapor is water in the form of a gas.Water vapor is invisible, unlike steam.
     • Particles
       • The air we breathe tiny particles of dust, smoke, salt, ect.
   • Importance of the Atmosphere
     • Earth's atmosphere makes conditions on Earth suitable for living things.
   • Air Quality
     • Sources of Pollution
       • Some pollution happens naturally. Most air pollution is the result of burning fossil fuels, such as coal, oil, gasoline, and diesel fuel.
     • Smog and Acid Rain
       • The burning of fossil fuels can cause smog and acid rain. Smog is smoky fog. Acid rain is rain that has more acid than normal in it.
   • Improving Air Quality
     • The EPA monitors air pollutants in the United States.Air quality has improved generally in the US but there must be more voluntary measures takes to help stop too much air pollution.

2. Air Pressure

   • 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 molecules, the density is less.
     • Pressure
       • The force pushing on an area or surface is known as pressure.The atmosphere is heavy The weight of the column of air above your desk is about the same as a large school bus.Molecules push from all sides, so the desk isn't crushed.
   • Measuring Air Pressure
     • Mercury Barometers
       • A mercury barometer consists of a glass tube open at the bottom end and partially filled with mercury. The space above the tube is almost a vacuum-it consists of very little air
     • Aneroid Barometers
       • An aneriod barometer has an airtight metal chamber. The metal chamber is sensitive to changes in air pressure. The higher the air pressure, the more the walls are pushed in.
     • Units of Air Pressure
       • Weather reports use several different units for air pressure. Most weather reports inches of mercury for general public. The National Weather Service indicates air pressure in millibars.
   • Altitude and the Properties of Air
     • Altitude Affects Air Pressure
       • Air pressure is greater at sea level because all the air fro above is pressing down on it. Air near the top of the atmosphere has less air pressure because there is less weight pressing on it from above.
     • Altitude Also Affects Density
       • As you go up through the atmosphere, the density increases.The higher up you are, the harder to breathe.

3. Layers of the Atmosphere

   • The Troposphere
     • The first layer of the atmosphere is where all the weather happens. Clouds go up to the tip of the troposphere and same with planes.
   • The Mesosphere
     • The mesosphere is the third layer of Earth's atmosphere and protects Earth from most meteoriods.
   • The Thermosphere
     • The thermosphere is the last and largest layer of the atmosphere. Even though the air is thin in the thermosphere, it is very hot. Reaching up to 1800 degrees celsius. The thermosphere is divided into two parts, the ionosphere and the exosphere.
     • Ionosphere
       • Energy from the sun causes gas molecules in the ionosphere electrically charged particles called ions.
     • Exosphere
       • The exosphere extends out from 400 kilometers for thousands of kilometers.
   • The Stratosphere
     • The stratosphere is the second layer of the atmosphere and it contains the ozone layer which protects the troposphere from the sun's ultraviolet light.

4. Energy in Earth's Atmosphere

   • Energy from the Sun
     • Visible Light
       • Visible light includes al of the colors that you see in a rainbow: red, orange, yellow, ggreen, blue, indigo, and violet. Differnet colors result in different wave lengths; red and orange are longer, but blue and violet are shorter.
     • Non-Visible Radiation
       • Three forms of non-visible radiation are infrared radiation, ultraviolet radiation, and Solar radiation.
   • 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. When you look at the sky, the light you see has been scattered by the gas molecules in the atmosphere.
   • 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 green house effect.

5. 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.
     • Temperature Scales
       • Temperature is measured in units called degrees. Two temperature scales are commonly used: the Celsius scale and the Fahrenheit scale.
   • 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
       • Within the troposphere, heat is transferred mostly by convection.

6. Winds

   • What is Wind
     • A wind is the horizontal movement of air from an area of high pressure, to an area of lower pressure. Winds are caused by differences in air pressure.
     • Measuring Wind
       • Winds are described by their direction and speed. Wind speed can be measured with an anemometer.
     • Wind-Chill Factor
       • On warm day, a cool breeze can be refreshing. The stronger the wind, the colder you feel. The increased cooling a wind can cause is called the wind-chill factor.
   • Local Winds
     • Local winds are winds that blow over short distances. 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 during the day.
     • Land Breeze
       • The flow of air from land to a body of water at night is called a land breeze.
   • Global Winds
     • Global Convection Currents
       • Temperature differences between the equator and the poles produce gaint convection currents in the atmosphere. Warm air rises at the Equator and cold air sinks at the poles.
     • The Coriolis Effect
       • As the wind blows, Earth rotates from west to east underneath them, making it seem as if the winds have curved. 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
       • The 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 Europe to 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.
     • Polar Easterlies
       • The Coriolis effect shifts these polar winds to the west, producing the polar easterlies.
     • Jet Streams
       • About 10 kilometers above Earth's surface are bands of high-speed winds called jet streams.