The Atmosphere

The Atmosphere

1. The Air Around You

   • Earth's atmosphere is the envelope of gases that surrounds the planet. Weather is the condition of Earth's atmosphere at a particular time and place.
   • Importance of the Atmosphere
     • Earth's atmosphere makes conditions on Earth suitable for living things.
   • Air Quality
     • You breathe in oxygen, which is needed, into your lungs, but sometimes you breathe harmful gases.
     • Sources of Pollution
       • Some Pollution occurs naturally, but most pollution is the result of burning fossil fuels, such as coal, oil, gasoline, and diesel.
     • Smog and Acid Rain
       • The burning of fossil fuels can cause smog and acid rain.
   • Improving Air Quality
     • The government has have passed a number of laws and regulations to reduce air pollution.
   • Composition of the Atmosphere
     • Earth's atmosphere is made up of nitrogen, oxygen, carbon dioxide, other gases, water vapor, and particles.
     • Nitrogen
       • The atmosphere consists of mostly nitrogen.
     • Carbon Dioxide
       • Each molecule of carbon dioxide has one atom of carbon and two atoms of oxygen.
     • Other Gases
       • The remaining gases are called trace gases because only small amounts of them are present.
     • Water Vapor
       • Water vapor is the form of water in a gas. You are not able to see it
     • Particles
       • The air we breath consists of dust, smoke,salt, and other chemicals.
     • Oxygen
       • Even though oxygen takes up the second most common thing in the atmosphere, it has less than 25%

2. 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
       • 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
     • Local winds are caused by the unequal heating of Earth's surface within a small area.
     • Sea Breeze
       • A sea 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 Wind Belts
     • The major global wind belts are the trade winds, the polar easterlies, and the prevailing westerlies.
     • Prevailing Westerlies
       • Prevailing westerlies blow away from the horse latitudes.
     • Trade Winds
       • The trade winds blow from the horse latitudes toward the equator.
     • Horse Latitudes
       • The horse latitudes are 30° north and south. It is called this because sailors didn't have enough food for the horses, so they threw the horses overboard.
     • Doldrums
       • Near the equator, the sun heats the surface strongly
   • Global Winds
     • Like local winds, global winds are created by the unequal heating of Earth's surface. But unlike local winds, global winds occur over a large area.
     • The Coriolis Effect
       • The Coriolis Effect is  the way Earth's rotation makes winds curve .
     • Global Convection Currents
       • Warm air rises at the equator and cool air sinks at the poles.

3. Layers of the Atmosphere

   • The Mesosphere
     • The mesosphere begins at 50 kilometers and ends at 80 kilometers. This layer protects the Earth's surface from being hit by most meteoroides.
   • The Thermosphere
     • The thermosphere is above 80 kilometers. It is the outermost layer of Earth's atmosphere.
   • The Stratosphere
     • Extends from the troposphere to about 50 kilometers above Earth's surface. The stratosphere is the second layer and contains the ozone layer.
   • The Troposphere
     • The troposphere is where weather occurs. We live in this layer

4. Heat Transfer in the Atmosphere

   • How Heat is Transferred
     • Heat is transferred in three ways: convection, radiation, and conduction.
     • Conduction
       • The direct transfer of heat from one substance to another is called conduction.
     • Radiation
       • The direct transfer of energy by electromagnetic waves.
     • Convection
       • The transfer of heat by the movement of a fluid is called convection.
     • Heating the Troposphere
       • Within the troposphere, the heat is transferred mostly by convection.
   • Thermal Energy and Temperature
     • The total energy of motion in the particles of a substance is called thermal energy.
     • Measuring Temperature
       • Air temperature is usually measured with a thermometer.
     • Temperature Scales
       • Temperature is measured in units called degrees.

5. Air Pressure

   • The weight of the atmosphere is constantly pressing on your body.
   • Properties of Air
     • Because air has mass, it also has other properties like density and pressure.
     • Density
       • The amount of mass in a given volume of air is its density.
     • Pressure
       • The force pushing on an area or surface is known as pressure
   • Measuring Air Pressure
     • A barometer is an instrument that is used to measure air pressure. Aneroid barometers and mercury barometers are two types of barometers.
     • Mercury Barometers
       • In a mercury barometer, when pressure increases , it presses on the mercury.
     • Aneroid Barometers
       • When air pressure increases, the thin walls of the chamber are pushed in.
     • Units of Air Pressure
       •  Inches and millibars are how they measure air pressure.
   • Altitude and the Properties of Air
     • Air pressure decreases as you get higher. As air pressure decreases so does density.
     • Altitude Affects Air Pressure
       • Sea-level air has the weight of the whole atmosphere pressing on it.
     • Altitude Also Affects Density
       • As you go up air density decreases.

6. Energy in Earth's Atmosphere

   • The movement of heat in the atmosphere causes temperature to drop, winds to blow, and rain to fall.
   • Energy From the Sun
     • Nearly all of the energy in Earth's surface comes from the sun.
     • Non-Visible Radiation
       • Infared radiation is not seen but instead it is felt.
     • Visible Light
       • Visible light includes all colors in a rainbow: red, orange, yellow, green, blue, indigo, and violet.
   • 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.
   • Energy at Earth's Surface
     • When Earth's surface is heated, it radiates most of the energy back into the atmosphere as infared radiation.