Chapter 3, Section 2
Learning Objectives <ul><li>Describe the composition and layers of the Earth’s atmosphere. </li></ul><ul><li>Explain three...
The Atmosphere <ul><li>Atmosphere – the mixture of gases that surrounds the Earth </li></ul><ul><li>Contains mostly nitrog...
 
Composition  of the  Atmosphere <ul><li>Nitrogen = 78% </li></ul><ul><li>Volcano eruptions </li></ul><ul><li>Dead plants a...
Composition of the Atmosphere <ul><li>Atmosphere also contains atmospheric dust </li></ul><ul><ul><li>Mainly soil </li></u...
Air Pressure <ul><li>Earth’s atmosphere is pulled toward Earth’s surface by gravity </li></ul><ul><li>This makes the atmos...
 
Layers of the Atmosphere <ul><li>The atmosphere is divided into four layers based on temperature changes that occur at dif...
 
The Troposphere <ul><li>Closest to Earth’s surface </li></ul><ul><li>18 km above Earth’s surface </li></ul><ul><li>Almost ...
The Stratosphere <ul><li>From 18 km to about 50 km </li></ul><ul><li>Temperature rises as altitude increases in stratosphe...
The Mesosphere <ul><li>From 50 km to 80 km above Earth’s surface </li></ul><ul><li>The coldest layer of the atmosphere </l...
The Thermosphere <ul><li>The layer farthest from the Earth’s surface </li></ul><ul><li>Nitrogen and oxygen absorb solar ra...
 
 
 
 
Three Types of Heat Transfer <ul><li>Radiation – Transfer of energy across space </li></ul><ul><li>Conduction – Flow of he...
Conduction, Convection, Radiation
Heating of the Atmosphere <ul><li>Solar energy reaches Earth as electromagnetic radiation. </li></ul><ul><ul><li>Electroma...
Movement of Energy in the Atmosphere <ul><li>Weather is caused by air that is constantly moving upward, downward or sidewa...
 
 
The Greenhouse Effect <ul><li>A greenhouse is a building where plants are grown. </li></ul><ul><li>Solar radiation enters ...
Greenhouse Gases <ul><li>Greenhouse Gases – The gases in our atmosphere that trap and radiate heat </li></ul><ul><li>None ...
The Greenhouse Effect <ul><li>The gases in Earth’s atmosphere act like the glass in a greenhouse. </li></ul><ul><li>Sunlig...
 
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The Atmosphere

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The Atmosphere

  1. 1. Chapter 3, Section 2
  2. 2. Learning Objectives <ul><li>Describe the composition and layers of the Earth’s atmosphere. </li></ul><ul><li>Explain three mechanisms of heat transfer in Earth’s atmosphere. </li></ul><ul><li>Explain the greenhouse effect. </li></ul>
  3. 3. The Atmosphere <ul><li>Atmosphere – the mixture of gases that surrounds the Earth </li></ul><ul><li>Contains mostly nitrogen, oxygen, carbon dioxide </li></ul><ul><li>These gases are constantly added and removed </li></ul><ul><ul><li>Animals and humans breath in and out </li></ul></ul><ul><ul><li>Plants produce food </li></ul></ul><ul><ul><li>Volcanoes erupt </li></ul></ul><ul><ul><li>Cars </li></ul></ul>
  4. 5. Composition of the Atmosphere <ul><li>Nitrogen = 78% </li></ul><ul><li>Volcano eruptions </li></ul><ul><li>Dead plants and animals decay </li></ul><ul><li>Oxygen = 21% </li></ul><ul><li>Plants </li></ul><ul><li>Other Gases = 1% </li></ul><ul><li>Argon </li></ul><ul><li>Carbon Dioxide </li></ul><ul><li>Methane </li></ul><ul><li>Water Vapor </li></ul>
  5. 6. Composition of the Atmosphere <ul><li>Atmosphere also contains atmospheric dust </li></ul><ul><ul><li>Mainly soil </li></ul></ul><ul><ul><li>Salt </li></ul></ul><ul><ul><li>Ash from fires </li></ul></ul><ul><ul><li>Volcanic ash </li></ul></ul><ul><ul><li>Particulate matter from combustion </li></ul></ul><ul><ul><li>Skin </li></ul></ul><ul><ul><li>Hair </li></ul></ul><ul><ul><li>Bits of clothing </li></ul></ul><ul><ul><li>Pollen </li></ul></ul><ul><ul><li>Bacteria and viruses </li></ul></ul><ul><ul><li>aerosols </li></ul></ul>
  6. 7. Air Pressure <ul><li>Earth’s atmosphere is pulled toward Earth’s surface by gravity </li></ul><ul><li>This makes the atmosphere denser near Earth’s surface </li></ul><ul><li>Almost the entire mass of Earth’s atmospheric gases is located with 30 km of the surface. </li></ul><ul><li>The air is less dense at higher altitudes. This makes breathing more difficult. </li></ul>
  7. 9. Layers of the Atmosphere <ul><li>The atmosphere is divided into four layers based on temperature changes that occur at different distances above the Earth’s surface. </li></ul><ul><ul><li>Troposphere </li></ul></ul><ul><ul><li>Stratosphere </li></ul></ul><ul><ul><li>Mesosphere </li></ul></ul><ul><ul><li>Thermosphere </li></ul></ul>
  8. 11. The Troposphere <ul><li>Closest to Earth’s surface </li></ul><ul><li>18 km above Earth’s surface </li></ul><ul><li>Almost all weather occurs here </li></ul><ul><li>Densest atmospheric layer </li></ul><ul><li>Temperature decreases as altitude increases </li></ul>
  9. 12. The Stratosphere <ul><li>From 18 km to about 50 km </li></ul><ul><li>Temperature rises as altitude increases in stratosphere </li></ul><ul><li>Ozone in the stratosphere absorbs the sun’s ultraviolet (UV) energy and warms the air </li></ul><ul><li>Ozone, O 3 , is made up of three oxygen atoms </li></ul><ul><li>Almost all ozone in the atmosphere is located in the ozone layer of the stratosphere </li></ul><ul><li>Ozone reduces the amount of UV radiation that reaches Earth. </li></ul>
  10. 13. The Mesosphere <ul><li>From 50 km to 80 km above Earth’s surface </li></ul><ul><li>The coldest layer of the atmosphere </li></ul><ul><li>Temperatures as low as -93°C. </li></ul>
  11. 14. The Thermosphere <ul><li>The layer farthest from the Earth’s surface </li></ul><ul><li>Nitrogen and oxygen absorb solar radiation </li></ul><ul><ul><li>The absorption causes atoms to be electrically charged. </li></ul></ul><ul><ul><li>These ions radiate energy as light. </li></ul></ul><ul><li>Temperatures above 2,000°C </li></ul><ul><li>If we could travel here, it would not feel hot to us </li></ul><ul><ul><li>Air particles that strike one another transfer heat </li></ul></ul><ul><ul><li>The air in the thermosphere is so thin that air particles rarely collide so they rarely transfer heat. </li></ul></ul>
  12. 19. Three Types of Heat Transfer <ul><li>Radiation – Transfer of energy across space </li></ul><ul><li>Conduction – Flow of heat from a warmer object to a colder object when placed in direct contact </li></ul><ul><li>Convection – The transfer of heat by air currents </li></ul>
  13. 20. Conduction, Convection, Radiation
  14. 21. Heating of the Atmosphere <ul><li>Solar energy reaches Earth as electromagnetic radiation. </li></ul><ul><ul><li>Electromagnetic radiation includes visible light, infrared radiation, and ultraviolet light. </li></ul></ul><ul><li>Almost half of the solar energy that enters the atmosphere passes through and reaches Earth’s surface </li></ul><ul><li>The rest is absorbed in the atmosphere by clouds, gases and dust or it is reflected by the Earth’s surface. </li></ul>
  15. 22. Movement of Energy in the Atmosphere <ul><li>Weather is caused by air that is constantly moving upward, downward or sideways </li></ul><ul><li>Currents of less dense air, warmed by the Earth’s surface, rise into the atmosphere. </li></ul><ul><li>Currents of denser, cold air sink toward the ground. </li></ul><ul><li>As currents of air rise into the atmosphere they cool off </li></ul><ul><li>Eventually, the air current becomes more dense than the air around it and sinks. </li></ul><ul><li>Convection current – Continual process of warm air rising and cool air sinking. A circular motion. </li></ul>
  16. 25. The Greenhouse Effect <ul><li>A greenhouse is a building where plants are grown. </li></ul><ul><li>Solar radiation enters the building and heats up the inside faster than heat can escape. </li></ul>
  17. 26. Greenhouse Gases <ul><li>Greenhouse Gases – The gases in our atmosphere that trap and radiate heat </li></ul><ul><li>None of the greenhouse gases have a high concentration in the Earth’s atmosphere </li></ul><ul><li>The most abundant greenhouse gases are </li></ul><ul><ul><li>Water vapor (varies because of natural processes) </li></ul></ul><ul><ul><li>Carbon dioxide (varies because of industry) </li></ul></ul><ul><ul><li>Methane (varies because of industry) </li></ul></ul><ul><ul><li>Nitrous oxide </li></ul></ul>
  18. 27. The Greenhouse Effect <ul><li>The gases in Earth’s atmosphere act like the glass in a greenhouse. </li></ul><ul><li>Sunlight penetrates the Earth’s atmosphere and heats the surface of the Earth. </li></ul><ul><li>The Earth’s surface radiates heat back to the atmosphere where only some of the heat escapes into space. </li></ul><ul><li>The rest of the heat is absorbed by the greenhouse gases, which warms the air. </li></ul><ul><li>Heat is then radiated back toward the surface of the Earth. </li></ul><ul><li>Without the greenhouse effect Earth would be too cold to live. </li></ul>

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