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Exploring Earth's Atmosphere: Importance, Composition, and Natural Cycles

Dive into the significance of Earth's atmosphere, its composition, natural cycles, and impact on climate. Learn about atmospheric pressure, gas composition, and factors influencing climate change. Understand the role of the Sun in heating the atmosphere and various energy transfer processes. Discover how vital the atmosphere is for sustaining life on Earth.

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Exploring Earth's Atmosphere: Importance, Composition, and Natural Cycles

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  1. ATMOSPHERE UNITChapter 15

  2. The AtmosphereChapter 15.1 Earth’s Atmosphere Supports Life

  3. State Objectives • Explain how carbon exists in different forms, such as limestone (rock), carbon dioxide (gas), carbonic acid (water), and animals (life) within Earth systems and how those forms can be beneficial or harmful to humans. • Describe natural mechanisms that could result in significant changes in climate (e.g., major volcanic eruptions, changes in sunlight received by the earth, and meteorite impacts).

  4. Book Objectives • Analyze how the atmosphere is important to living things. • Explain what the atmosphere is made of. • Describe how natural cycles affect the atmosphere.

  5. Characteristics of the Atmosphere • Atmosphere: the mixture of gases that surrounds the Earth. • contains oxygen needed for respiration • protects living things from the sun’s harmful rays • keeps Earth warm • transport energy to different regions of the planet

  6. Atmospheric Pressure • Air Pressure: the measure of the force with which the air molecules push on a surface • Changes throughout the atmosphere • Altitude: the height of an object above the Earth’s surface • Inverse relationship between Altitude & Air pressure Altitude Air pressure

  7. Atmospheric Pressure

  8. Atmospheric Pressure • Why? • Air becomes less dense as you travel upward. • Less molecules in the same amount of space means less pressure. • No “top” to atmosphere • About 500 km (300 miles) up is considered “outer space” • 99% of atmosphere is in the bottom 30 km (20 miles).

  9. Composition of the Atmosphere Today • Gases • Nitrogen: 78% • Oxygen: 21% • Argon, carbon dioxide & other: 1% • (water vapor amounts vary) • Solids • Ex. dust, dirt, smoke, volcanic ash • Liquids • Most common: water (in the clouds)

  10. Gases in the Atmosphere Today

  11. Earth’s Early Atmosphere • Water Vapor: 79% • Carbon Dioxide: 11 – 12% • Sulfur Dioxide: 6% • Nitrogen: 1% • Other gases: 1 % • Changed due to photosynthesis

  12. Gases in the EarlyAtmosphere

  13. Atmosphere from space

  14. Natural Cycles That Affect the Atmosphere • Carbon Cycle • Plants take in CO2 to use for photosynthesis • Plants and animals give off CO2 during cellular respiration

  15. Natural Cycles That Affect the Atmosphere • Nitrogen Cycle • Organisms in the soil take N2 from the air • The soil releases N2 back into the air

  16. Natural Cycles That Affect the Atmosphere • Water Cycle • H2O evaporates from oceans, lakes, ponds, etc. • Plants and animals give off H2O • Liquid H2O falls from the atmosphere as rain

  17. Sudden Changes That Affect the Atmosphere • Volcanic Eruptions • Gases and ash can affect the weather and climate worldwide by blocking sunlight and lowering temperatures. • Forest fires • Dust storms

  18. Day 2 Warm-up Quiz • What are the two main gases in Earth’s atmosphere? • What is atmospheric pressure? • What causes air pressure? • Why does atmospheric pressure decrease as altitude increases? • Name the layers of the atmosphere, starting with the one closest to Earth. • Why can the thermosphere have high temperatures but not feel hot?

  19. The AtmosphereChapter 15.2 The Sun Supplies the Atmosphere’s Energy

  20. State Objectives • Describe the Earth’s principal source of external energy. • Describe natural processes in which heat transfer in the Earth occurs by conduction, convection, and radiation. • Identify the main sources of energy to the climate system.

  21. Book Objectives • Explain how solar energy heats Earth’s surface and atmosphere • Explain how the atmosphere moves heat energy around. • Name and describe the layers of the atmosphere.

  22. Heating of the Atmosphere • The Sun is our principle energy source. • 2 things can happen to energy from the sun: • 30% is reflected by clouds, atmosphere & surface • 20% is absorbed by clouds, atmosphere • 50% is absorbed at the surface by oceans, land & living things

  23. Heating of the Atmosphere • Radiation: the transfer of energy as electromagnetic waves. • Not all of the radiation reaches the earth’s surface. • Radiation absorbed by the land, water & atmosphere is changed into thermal energy.

  24. Radiation and the Atmosphere

  25. Heating the Earth & Atmosphere • Radiation – EM waves from the sun moves energy through space to the Earth. • Conduction: the transfer of thermal energy from one material to another by direct contact. • Thermal energy always moves from warm to cold. • When air molecules come into direct contact with a warm surface, they heat up.

  26. Heating the Earth & Atmosphere • Convection: the transfer of thermal energy by the circulation or movement of a liquid or gas. • Most thermal energy in the atmosphere moves this way • Remember: warm air is LESS dense than cool air, so. . . Warm air rises and cold air sinks

  27. Convection Currents Air is cooled as it goes higher into the atmosphere. As air cools it becomes more dense. Warm air rises As the Cool air sinks, it pushes the warm air up Air becomes less dense as it is warmed at the surface of the earth.

  28. Radiation, Convection & Conduction

  29. Day 3 Warm-up Quiz • Which three gases in the atmosphere are especially important to plants? • Draw a diagram to show how one natural cycle affects the atmosphere. • What two things happen to solar radiation that reaches Earth? • List three ways the atmosphere moves energy. • Which way involves waves? • Which transfers energy by motion of a heated gas or a liquid? • Which involves direct contact?

  30. Layers of the Atmosphere • Troposphere • Stratosphere • Mesophere • Thermosphere

  31. Atmospheric Temperature • Temperature changes from layer to layer • Each layer is defined by a temperature change

  32. Troposphere • Troposphere: lies next to the Earth’s surface. • Lowest, densest layer • Contains about 80% of atmosphere’s total mass • This is where clouds, weather, pollution, and most life-forms are found • Temperature falls with increasing altitude • about - 60° C (-76° F) at the top

  33. Stratosphere • Stratosphere: atmospheric layer above the troposphere. • Very thin air, very low moisture • Extremely cold in lower(-60° C ) • Contains the ozone layer • Temperature rises with increasing altitude because of the ozone layer

  34. Mesosphere • Mesosphere: the coldest layer of the atmosphere located above the stratosphere. • Temperature drops with increasing altitude. • Temp at the top: about - 85° C (-120° F) • Has large wind storms

  35. Thermosphere • Thermosphere: uppermost atmospheric layer. • Temperature rises with increasing altitude. • Temp can reach: 1,700° C • BUT, it would not FEEL hot because particles are so far apart they rarely touch to transfer heat. • Remember: Temperature and heat are NOT the same thing!

  36. Ionosphere • Located in the upper part of the mesosphere and the lower thermosphere. • Absorbs X-rays and gamma rays • Made of electrically charged particles called ions. • Aurora borealis (Northern Lights) occurs here

  37. Aurora Borealis“Northern Lights”

  38. Aurora Australis“Southern Lights”

  39. Layers of the Atmosphere

  40. Profile of the Earth’s Atmosphere

  41. Learning Check-up • What characteristic do scientists use to define four layers of Earth’s atmosphere? • Explain how density affects energy transfer in the air. • Why does the temperature vary as altitude increases? • Complete a table entitled “The Atmosphere” with these four headings: Layer Altitude Temperature Other Range Range Important Information

  42. The AtmosphereChapter 15.3 Gases in the Atmosphere Absorb Radiation.

  43. State Objectives • Explain the natural mechanism of the greenhouse effect, including comparisons of the major greenhouse gases (water vapor, carbon dioxide, methane, nitrous oxide, and ozone).

  44. Book Objectives • Describe two ways that radiation and gases affect each other. • Explain that the ozone layer absorbs ultraviolet radiation • Explain how Earth’s surface and greenhouse gases affect infrared radiation.

  45. EM Radiation Review • Ultraviolet radiation • Radiation of higher frequencies (more energy) than visible light. • Can cause sunburn, skin cancer and other types of damage. • Infrared radiation • Radiation of lower frequencies (less energy) than visible light. • Detected as heat.

  46. Ozone Layer • Ozone: a molecule that is made up of three oxygen atoms (O3). • Ozone Layer is located in the Stratosphere. • Absorbs ultraviolet radiation while allowing other radiation to pass through • Protects life on Earth from ultraviolet radiation

  47. Ozone Layer

  48. Ozone Layer • In the stratosphere, ozone is constantly being formed and broken apart in a natural cycle

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