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The Atmosphere

The Atmosphere. Atmospheric Composition. Structure of Atmosphere. Structure of Atmosphere. Weather and Climate. WEATHER ≠ CLIMATE. Weather. The short-term conditions of the atmosphere in a given place Influenced by the movement or transfer of heat energy Influences: Temperature

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The Atmosphere

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  1. The Atmosphere

  2. Atmospheric Composition

  3. Structure of Atmosphere

  4. Structure of Atmosphere

  5. Weather and Climate

  6. WEATHER ≠ CLIMATE

  7. Weather • The short-term conditions of the atmosphere in a given place • Influenced by the movement or transfer of heat energy • Influences: • Temperature • Air pressure • Humidity • Precipitation • Available sunshine (lack of cloud cover) • Wind speed • Wind direction

  8. She is reporting weather

  9. Climate • The total of all weather occurring over a period of years in a given place • Energy transfered through: • Radiation • Conduction • Convection

  10. Air Mass Air Pressure Albedo Altitude Angle of sunlight Carbon Cycle Clouds Distance to Oceans Fronts Greenhouse Effect Heat (convection) Land Changes Land mass distribution Latitude Location Moisture content of the air Mountain ranges Plate Tectonics Pollution Precession Rotation Solar Output Volcanoes Wind Patterns Human Activity Factors that influence climate

  11. Air Mass • Large Body of air that has similar temperature and moisture content • Categorized by: • Equatorial • Tropical • Polar • Arctic • Continental • Maritime

  12. Air Pressure • Decreases with altitude (99% within 20 mi of earths surface) • Low Pressure Masses: produces cloudy and stormy weather • High Pressure masses: contain cool dense air; drops to Earth’s surface and becomes warmer • Associated with fair (nice) weather

  13. Albedo • Reflectivity • Oceans – low • Land masses – moderate • Snow and Ice – high • Positive feedback mechanism • Dust in air can form a high albedo layer in the atmosphere and reflects sunlight back • Temporarily cooling the atmosphere

  14. Altitude • Every 1000 feet (300m) rise in elevation = 3°F drop in temperature • Every 300 feet (90m) rise in elevation = 62mi (100 km) shift north in latitude and biome similarities

  15. Altitude changes

  16. Angle of sunlight • Areas of the earth closest to the sun receive more sunlight and have a higher temperature

  17. Carbon Cycle

  18. Clouds • Collections of water droplets or ice crystals suspended in the atmosphere

  19. Distance to Oceans • Oceans are thermally more stable than land • Changes in temperature are more extreme in center of land masses than near the oceans

  20. Fronts • Boundary between two air masses • Vary by • Temperature • Dew point • Wind direction • Cold fronts – leading edge of an advancing cold air mass • Associated with thunderstorms

  21. Greenhouse effect • Water, carbon dioxide, and methane trap solar radiation • Too much = Earth too hot to live on • Too little = Earth too cold to live on

  22. Convection: Primary way energy is transferred from hotter to colder regions in the Earth’s atmosphere Primary determinant of weather patterns Conduction: Involves the heat transfer through a substance heat results from different temperatures in different parts of that substance Heat (Convection)

  23. Atmospheric Convection Cell

  24. Land Mass Distribution • Oceans absorb more solar heat than land masses • Earth receives more solar radiation at low latitudes (near the equator) than at high latitudes • More landmasses near the equator leads to a cooler planet

  25. Latitude • High latitude = less solar radiation = cooler climate

  26. Land Changes • Deforestation • Urbanization

  27. Moisture Content (Humidity) • Atmospheric water vapor: • Provides moisture for clouds and rain • Acts as a green house gas keeping the Earth warm • A primary determinant of plant growth • Determines type of biome • Dew point – temperature at which condensation takes place

  28. Mountain Ranges • Force air masses from a low elevation to a high elevation • Air mass expands and cools as it rises • Relative humidity is raised • Clouds form (sometimes get rain) • Windward side of the range gets the most rain • The leeward side gets the least rain creating a rain shadow effect and producing a different biome

  29. Rain shadow effect

  30. Plate Tectonics • Stable plate tectonics leads to less volcanism • Less volcanism means less carbon dioxide in the atmosphere  cooler planet • More plate movement  more volcanism  more greenhouse gasses  hotter planet

  31. Pollution • Greenhouse gasses from human sources  increase in global temperature • CFC’s damage the ozone layer • Excess sulfur  acid rain

  32. Precession • Precession – the wobble of the Earth on it’s axis • Changes in precession  changes in the amount of sunlight the earth receives  atmospheric changes

  33. Rotation • Daily temperature changes are affected by the Earth’s 24 hour rotation cycle (1 day) • Solar radiation warms the planet during the day • Heat escapes the planet at night

  34. Solar Output

  35. Radiation • Flow of electromagnetic radiation from the sun • Adds energy to the Earth’s systems

  36. Volcanoes • Volcano aerosols: • Sulfur ejected into the stratosphere warms the stratosphere and cools the troposphere. • Can destroy ozone • Carbon dioxide – green house gas • Increased iron  increased biological activity  take up carbon dioxide and cool the atmosphere • Large eruptions may trigger El Niño events

  37. Wind Patterns • Influenced by: • Temperature • Pressure differences • Coriolis effect

  38. Wind Patterns • Sun heats the atmosphere unevenly • Air closest to the surface warms and rises • Air at high elevations cools and sinks • Rising and falling sets up a convection process  wind

  39. Global Air Circulation • Caused and affected by: • Uneven heating of the Earth’s surface • Seasons • The Coriolis effect • The amount of solar radiation reaching the earth’s surface over a given period of time • Convection cells created by areas of warm ocean water

  40. Coriolis Effect • Once an air mass is set in motion (by pressure gradients) it undergoes an apparent deflection from it’s path due to the rotation of the earth • Coriolis force at Equator is zero

  41. Trade Winds • Caused by Coriolis effect • Determined shipping routes during the Age of Sail

  42. Human Activity • Human activities that affect the climate: • Deforestation • Urbanization • Heat island effects • Release of pollutants • Burning fossil fuels • Produce acid rain

  43. Major Climate Periods

  44. Major Climate Periods

  45. Atmosphere Circulation Cells • Hadley Air Circulation Cells • Ferrel Air Circulation Cells • Polar Air Circulation Cells Help determine biomes and biogeography of the Earth

  46. Winds • Isobar Map – shows wind speeds over a geographic area • The closer the bars are the greater the wind speed

  47. Hadley Air Circulation Cells • Air is heated at the equator, rises and expands north and south

  48. Ferral Air Circulation Cells • Develop between 30N and 30S latitude • Mid-latitude climates have servere winters and cool summers, defined seasons

  49. Polar Air Circulation Cells • Icy dry air from poles meets moist tropical air from mid-latitudes • Air returns to the poles, cooling and sinking, causing precipitation • Very little liquid water – most is ice or snow

  50. The whole picture…

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