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PHYS-575/CSI-655 Introduction to Atmospheric Physics and Chemistry

PHYS-575/CSI-655 Introduction to Atmospheric Physics and Chemistry. Lecture Notes 1 – Part 1 Earth: The water planet Take a deep breath Some basics ideas/concepts Why study the atmosphere? Climate change issues Survey of planetary atmospheres.

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PHYS-575/CSI-655 Introduction to Atmospheric Physics and Chemistry

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  1. PHYS-575/CSI-655Introduction to Atmospheric Physics and Chemistry Lecture Notes 1 – Part 1 • Earth: The water planet • Take a deep breath • Some basics ideas/concepts • Why study the atmosphere? • Climate change issues • Survey of planetary atmospheres

  2. Is there anything in this picture that is not influenced by water? Is there anything in this picture not influenced by life? Is there anything in this picture not influenced by the atmosphere? Earth – The Water Planet

  3. What is Atmospheric Science? Atmospheric Scienceis an applieddiscipline that is concerned with the structure and evolution of planetary atmospheres and with the wide range of phenomena that occur within them. Atmospheric Science includes: - weather and weather forecasting - climate and climate change - atmospheric chemistry - atmospheric observations Atmospheric Science overlaps many traditional disciplines: - physics, chemistry, geology, biology, astronomy (e.g. biogeochemical cycles of carbon, oxygen, nitrogen….) In general, Atmospheric Science is the study of the characteristics of the thin gaseous envelope around a planet, its interactions with the planet below and space above, and its evolution over time.

  4. The Earth’s Atmosphere is Thin

  5. Atmospheric Layers

  6. What is the air we breath? What is in one breath of air? Atoms and Molecules: ~ 3 x 1022 mostly O2 and N2 molecules; elements forged by nuclear reactions in the interiors of stars.  Oxygen (O2) cycles through the biosphere (photosynthesis and respiration) roughly every 6000 years.  Nitrogen (N2) cycles with a 2 million year time scale. These molecules move at near the speed of sound and experience billions of collisions per second. How many molecules in one breath of air were at one time breathed by Julius Caesar? D. Bodanis “It’s in the air: skin, stardust, radio waves, vitamins, spider legs” Smithsonian Magazine, April, 1995.

  7. What is in the air we breath? A Few of the Other Gases in the Atmosphere:  Methane (CH4) from cows belching…  Argon (Ar) from extinct volcanoes  Water vapor (H2O) from impacting comets and meteorites over 4.5 BYA, or released from the deep interior of the Earth.  Carbon Dioxide (CO2) from respiration and fossil fuel burning.  Hydrogen Sulfide (H2S) from blue-green algae Overall, there are more than 2000 measurable trace gases in a liter of air.

  8. It’s in the Air… Even the cleanest liter of air has a vast amount of particulate matter. Dust:~ 100,000 dust particles of wide range of compositions: sea salt – many thousands per cc. pollen, spores – tens of thousands broken bits of insect (mostly spider) legs - thousands smoke (soot) from around the world - thousands meteoric dust from outer space - thousands DNA fragments from decaying bacteria, skin flakes, soil, pet fur, dander, dust mites millions of bacteria from your classmates. Even the cleanest “Clean Room” has > 10000 particles per liter of air.

  9. Atmospheric Composition • Concentration • Number density: • molecules/cm3 • Fractional Concentration: • No. ofmolecules/total density • Fractional concentration is • also referred to as: • Mixing Ratio • Molar Fraction • Volume Mixing Ratio

  10. What Determines the Atmospheric Composition? Almost all atmospheric gases are produced/consumed or moderated by life.

  11. Where does Oxygen (O2) come from? Biological organisms, via photosynthesis, metabolize water and carbon dioxide to form carbohydrates and produce oxygen as a by-product. Photosynthesis:(+sunlight) Water + carbon dioxide  glucose + oxygen 6 H2O + 6 CO2  C6H12O6 + O2 Green trees and plants are the major source of oxygen on land. Phytoplankton are capable of consuming the nutrients in the euphotic zone of the ocean in a matter of days, requiring continual replenishment. Primary Productivity (photosynthesis) Respirationis the reverse process which oxidizes organic material and removes O2.

  12. Oxygen Sources, Reservoirs and Cycles

  13. Atmospheric Nitrogen – Sources and Sinks

  14. The Carbon Cycle

  15. Primary Drivers of Biogeochemical Cycles

  16. Atmospheric Description:Vertical Temperature Structure of the Earth’s Atmosphere The characteristics of the vertical temperature profile are produced by heating and/or cooling processes. Thermosphere - ions Mesosphere - meteors Stratosphere - ozone Troposphere - weather

  17. Fundamental Relationships: Downward force (weight) due to gravity (g = gravitational acceleration): (F = force per unit volume; ρ = mass density) Pressure is due to the overlying weight of atmosphere: Thus, P = mg (where m is mass of atmosphere per unit area) It follows that the change in pressure with altitude is This is known as the Hydrostatic Relationship. It implies that pressure decreases exponentially with altitude, which we will see later.

  18. The Ideal Gas Law Where R is the gas constant, ρ is mass density, and T is the temperature in Kelvin. Alternatively: Where k is the Boltzman Constant, n = # density

  19. Vertical Density Structure If pressure decreases exponentially with altitude, then density will decrease at the same rate.

  20. Horizontal Variation on a Wide Range of Scales http://rst.gsfc.nasa.gov/Sect14/milthorpeincus.jpg SEAWiFS Image

  21. Coordinate System Latitude – measured from equator Longitude – measured WRT to Greenwich meridian Altitude – measured WRT sea level

  22. The Atmospheric General Circulation:Driven by Differential Solar Heating

  23. Zonal Average Structure Zonal averages are 2 dimensional average value of winds, temperature, etc., around a latitude circle

  24. Circulation: Highs and Lows

  25. Trade Winds

  26. Winds, Rainfall, Surface Temperature

  27. Idealized Surface Winds vs. Actual Surface Winds http://z.about.com/d/space/1/7/e/e/pia01347.jpg

  28. Sea Surface Temperature, Land Surface Temperature, and Clouds http://www.mhhe.com/earthsci/geology/mcconnell/earths_climate/images/temp_cloud_map.gif

  29. Precipitation (mm) http://www.geo.arizona.edu/Antevs/nats104/sld15b.gif

  30. Atmospheric Structure: Variability and Internal/External Influences http://www-frd.fsl.noaa.gov/mab/scatcat/khwavephoto-opt2.jpg Kelvin-Helmholtz Breaking Waves

  31. Volcanic Influences on the Atmosphere This eruption occurred at the Chaiten Volcano in Southern Chile on May 7, 2008. http://cache.io9.com/assets/resources/2008/05/chilevolcano.jpg

  32. Solar Influences on the Earth http://stereo.gsfc.nasa.gov/img/spaceweather/preview/tricompSW.jpg

  33. Continued Evolution – Human Influences Mauna Loa

  34. The Antarctic Ozone Hole Ozone Depletion is a Global Phenomena. But the arctic regions, in particular the Antarctic, acts to magnify the ozone depletion at certain times of the year. This is known as the Ozone Hole.

  35. Current interest in past and future climates is due to several factors: • Detailed reconstructions of past climates show that the climate has varied on all time scales from decades to millions of years. • Research focused on human activities on the environment has demonstrated that humans are influencing climate. • And finally, there is observational evidence that world climate is changing rapidly (IPCC, 2007).

  36. Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (2007) Global Average Temperature Global Average Sea Level Northern Hemisphere Snow Cover

  37. Weather Prediction Weather Prediction is the most practical application of atmospheric science. But refinements in weather prediction require improvements in our understanding of the entire atmospheric system and the various external and internal forcing mechanisms. Furthermore, understanding the structure and evolution of the atmosphere of other planets gives us a clearer understanding of the range of phenomena possible on Earth. In some cases we have recognized important chemical and physical processes on other planets before we knew of their importance for the Earth system.

  38. Observing the Atmosphere Observing Platforms: Balloons – Radiosondes Weather Airplanes Weather Radar Weather Satellites Atmospheric Variables: Temperature Pressure Relative Humidity Winds Trace Gas Abundances

  39. Atmospheric Observations: Weather Satellites http://www.eohandbook.com/eohb05/images/fig_03_(weather).jpg

  40. Mediterranean Dust & Smoke from the SEAWifs Satellite http://jwocky.gsfc.nasa.gov/aerosols/today_plus/yr2000/seawifs_med000825.jpg

  41. Greek Fires from MODIS Satellite http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=14469

  42. Hurricane Katrina from the SEAWifs Satellite

  43. Gustav – Projected Path

  44. What is the source of illumination of the rocket trail?

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