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Chapter 37

Chapter 37. The Atmosphere, the Oceans, and their Interactions. Earth Facts. 70% of the Earth is water The oceans are the source for precipitation Water has a large heat capacity and slowly warms and cools

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Chapter 37

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  1. Chapter 37 The Atmosphere, the Oceans, and their Interactions Presented by April Senger

  2. Earth Facts • 70% of the Earth is water • The oceans are the source for precipitation • Water has a large heat capacity and slowly warms and cools • San Francisco, CA and Wichita, KS have the same latitude but different summers and winters Presented by April Senger

  3. The Early Atmosphere • The Earth and other planets were thought to mostly have similar atmospheres of H, He, some methane and ammonia before the Sun’s full formation • When the Sun was born it gave off a blast that swept away these early atms • The Earth’s volcanoes and fissures leaked trapped gases with about 85% water vapor, 10% carbon dioxide, and 5% oxygen Presented by April Senger

  4. Oxygen • In the beginning, there was no free oxygen • Without free oxygen you can not support life • Stromalites (first primitive plants) and green algae used photosynthesis to convert carbon dioxide and water into hydrocarbons and free oxygen • Free oxygen can combine to form O3 or ozone that acts like a sun filter Presented by April Senger

  5. A Hot Ball of Cooling Magma • As the Earth cooled, the water vapor condensed and fell as precipitation • Soon oceans began to form • Oceans are essential to the evolution of life and ultimately the development of the present global environment which might prove to shape history • Evolution, for the purpose of this class, simply will mean change of form over time Presented by April Senger

  6. Concept Check • Why are the hottest climates on the Earth typically found in continental interiors? • They are away from coastlines that tend to keep temperatures constant • Did the ozone layer exist before the Earth acquired green plants? • No, you need free oxygen from photosynthesis to form ozone Presented by April Senger

  7. Gravity & the Atm • The Earth’s gravity pulls all atoms towards the surface • If the atoms were not moving, they would all lay in a pile at the surface • Atoms are moving at about 450 m/s and can rise up to 50 km in height • If there was no gravity, we would not have a force to hold the atoms = no atm Presented by April Senger

  8. Air Pressure • Air has weight and it presses down with air pressure or atmospheric pressure • 99% of the atm’s weight is below 30 km in altitude • As you climb mountains, the atm does thin • The weight of the air on the ocean’s surface keeps it from boiling away • Nitrogen (78%), Oxygen (21%), Argon (.9%), and Carbon Dioxide (.035%) are the main components of our atm and its pressure Presented by April Senger

  9. Troposphere • The troposphere is the atm layer closest to the Earth’s surface where nearly all weather occurs • Tropo extends 16 km up • It is the thinnest layer but contains 90% of the mass of the atm, water vapor and clouds • Pilots tend to fly at the top of the tropo just above the weather to make the flight less bumpy • Temps slowly decrease in height to -50 degrees C Presented by April Senger

  10. Stratosphere • The stratosphere extends upward 50 km from the tropo and contains the ozone layer • It extends from the tropo’s 16 km height to 50 km in altitude • Temps start at -50 and end at 0 degrees C Presented by April Senger

  11. Mesosphere • The mesosphere is the coldest layer • The altitude extends from 50-80 km • There are very few gases to absorb the sun’s rays so its temperatures drop again • Temps start at 0 and range to -90 degrees C Presented by April Senger

  12. Thermosphere • The thermosphere is the warm layer above the mesosphere • The temperatures vary very little and have no range due to the small number of molecules in the atm • It reaches an altitude of 500 km Presented by April Senger

  13. Ionosphere • The ionosphere is the layer that traps ions and is famous for the Northern lights • It is wihin the thermosphere and uppermost mesosphere • Interactions with the ions and high frequency solar radiation strip electrons from N & O atoms producing postive ions and free electrons • The activity depends on atm density (low is more active) and amount of solar radiation Presented by April Senger

  14. Exosphere • Above 500 km is the thinning atm that gradually yields to the radiation belts and magnetic fields of space • There is little to no atoms here • The temperature is very cold because of the lack of molecules to absorb the solar radiation Presented by April Senger

  15. Concept Check • Why do commercial airlines tend to fly at the top of the troposphere? • Most of the weather patterns would be below them and they would have less disturbances in flight Presented by April Senger

  16. Greenhouse Effect & Global Warming • The greenhouse effect is the warming of the lower atmosphere and plays a significant role in global warming • Water is the atm gas with the largest impact on warming, not carbon dioxide • The Earth has steadily increased .6 degrees C since 1850. What are some concerns with Global Warming? • What are some of the arguments against Global Warming Presented by April Senger

  17. Concept Check • What is the primary contributor to greenhouse gases in the Earth’s atmoshpere? • Volcanoes… • In 1991 Mount Pinatubo spewed more chlorine into our atm than the combined leakage of CFC’s over a century Presented by April Senger

  18. The difference in pressure between two different locations is called pressure gradients Convection currents in the atm result in wind as a result of pressure gradients The Coriolis effect is when the wind should move in a straight line but because of the Earth’s rotation, it forces currents to bend Friction with the surface slows winds and decreases the impact of the Coriolis Effect In the Northern Hemi, high pressure is clockwise and low is counter clockwise In the Southern Hemi, it is the opposite Pressure Gradients Presented by April Senger

  19. Doldrums • Doldrums are convection cells that are still, hot, and stagnant near the equator • When the moist air above the doldrums rise, it releases torrents of rain • The high amounts of rain are perfect conditions for the development of rainforests on continents near the equator Presented by April Senger

  20. The air from the doldrums moves away from the equator and at about 30 degrees latitude it cools Cold sinks and is compressed This air is hot and dry On land it breeds deserts such as the Sahara in Africa, the Arabian of the Middle East, the Mojave in the US, and the Great Victoria Desert of Australia At sea it has weak air currents and ships become stranded In old times sailors either ate their horses or throw them overboard to conserve water thus the name of this latitude Horse Latitudes Presented by April Senger

  21. Trade Winds & Westerlies • The thermal convection cycle that starts at the equator is completed when air flowing southward from the horse latitudes in the NH and northward in the SH is deflected westward • Air flowing northward from the Horse latitudes in the NH and southward in the SH is deflected eastward to produce the Westerlies Presented by April Senger

  22. Polar Easterlies • Cold air continuously sinks in the poles and pushes surface air outward • The Coriolis effect is very evident at the poles and deflects winds west to create the polar easterlies • The cool dry polar air meets the warm moist air of the westerlies at 60 degrees N and S at the polar front resulting in storms Presented by April Senger

  23. Making Predictions • The midlatitudes are noted for being unpredictable • As air moves from regions of high pressure, where air is denser, towards regions of low pressure, the result is a cyclone effect • Irregularities in the Earth’s surface influence wind behaviors • Mountains, valleys, deserts, forests & large bodies of water play a role Presented by April Senger

  24. Jet Streams • Rivers of wind at 9-14 km altitude are called Jet Streams traveling at 95-190 km per hour • The polar jet stream (60 degrees N & S) builds at the polar front and brings winter blizzards to North America • At 30 degrees N & S warm air leaving the equator creates a gradient and strong winds called the subtropical jet stream • The monsoons of SE Asia, India and Africa are a result of subtropical jet streams Presented by April Senger

  25. Concept Check • What are the main causes of trade winds, jet streams, monsoons and their bearing on the world’s climate? • Unequal heating of the Earth’s surfaces and the Earth’s rotation • In the mid-altitudes, airlines schedule shorter flight times traveling west to east and longer for east to west. Why? • West to east can travel with the jet stream • East to west avoid the jet stream Presented by April Senger

  26. Ocean Currents • Ocean currents are fueled by wind-driven currents (coastal boundaries) and density-driven currents (temperature and salinity) • Salts make up 99.7% of the ocean’s dissolved materials and is measured by salinity • Salinity is the amount of salt in 1000 grams of seawater • Average salinity is 96.5% water and 3.5% salt • We notice the ocean has a surface zone, transition zone and deep zone Presented by April Senger

  27. Coriolis and Oceans • If the wind is present for short distances, the ocean moves in the same direction as the wind • If the wind is present for greater distances, the Coriolis effect causes the water to bend clockwise in the NH and counter clockwise in the SH called gyre Presented by April Senger

  28. Importance of Gyres • Gyres are the circulation patterns you may notice on page 676 of our book • They are important because they carry warm water to the higher latitudes • One that is very important to the US is the Gulf Stream (or Kuroshio in the SH moving counter clockwise) Presented by April Senger

  29. Deep Water Currents • Deep water currents move slowly and vertically by gravity due to density differences • Sea water is difficult to freeze • When it turns to ice it leaves the salt behind making the surrounding water saltier (more dense) • It begins to sink and creates a conveyor belt circulation • Example: the currents of Iceland and Greenland Presented by April Senger

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