1. CHAPTER 1 Structure & Composition of Earth’s Atmosphere THE TURBULENT ATMOSPHERE CHAPTER 1 Structure & Composition of Earth’s Atmosphere THE TURBULENT ATMOSPHERE

2.  “Extreme and unusual weather” are the focus of public fears, and are often the impetus behind our quest for knowledge about the atmosphere  In the United States, the risk of death due to a weather event is relatively small when compared to other risks ◦ About two in one million

3. Table 1.1, p. 5

4.  Weather-related events cause an estimated $10 billion in property damage annually  Virtually no part of the globe is free of the threat of extreme weather

5. Fig. 1.2, p. 5 The total number of billion dollar weather and climate disasters from 1980 through 2004.

6. Fig. 1.3, p. 5 Note! Represents Percentages in One Year Only: 2000 Weather-related Deaths

7.  There are a number of concerns about the atmosphere that are not related to isolated extreme weather events ◦ Global warming ◦ Toxic chemicals  A basic understanding of the atmosphere is required for understanding the acute impacts caused by extreme and unusual weather

8. Fig. 1.4, p. 7

9. Table 1.2, p. 6

10.  Our atmosphere is a thin, delicate life- giving blanket of air that surrounds the earth  Warmth for our planet is provided primarily by the sun’s energy

11. Diagram NOT to scale

12.  Our atmosphere is a thin, delicate life-giving blanket of air that surrounds the earth  Warmth for our planet is provided primarily by the sun’s energy  Radiant energy drives the atmosphere into the patterns of everyday wind and weather, and allows life to flourish  Mean sfc temp is 59F (15C), but can be much more extreme

13. Mr. Hartwell -- F-M Meteorology Earth’s Atmosphere * Formation *

14. Before the Solar System Supernova explosion provides raw materials Materials collect around a center of gravity to ignite the Sun

16. Formation of Earth 4.6 billion years old Coalescence of rocky particles Atmosphere forms later

17. Formation of Earth’s Atmosphere Original Protoearth was molten Dense material (molten nickel and iron) flowed to the center Lighter material (molten silicon) flows to the top Earth cools and solidifies into basic core, mantle and crust structurestructure The earth has a lot of trapped gasses in its interior Movie clip!

18. Atmosphere #1 Composition - Probably H2, He Gases are relatively rare on Earth Probably lost to space early in Earth's history because…? –Earth's gravity is not strong enough to hold lighter gases –Earth still did not have a differentiated core (solid inner/liquid outer core)  creates Earth's magnetic field (magnetosphere = Van Allen Belt)  deflects solar winds. Once the core differentiated the heavier gases could be retained

19. Atmosphere #2 Produced by volcanic out-gassing (degassing).

20. Current Atmosphere

23. Atmosphere #2 Produced by volcanic out-gassing (degassing). Gases produced were probably similar to those created by modern volcanoes (H2O, CO2, SO2, CO, S2, Cl2, N2, H2) and NH3 (ammonia) and CH4 (methane) No free O2 at this time (not found in volcanic gases). Ocean Formation - As the Earth cooled, H2O produced by out gassing could exist as liquid in the Early Archean, allowing oceans to form. –Evidence - pillow basalts, deep marine seds in greenstone belts.

24. Production of Oxygen Photochemical dissociation - breakup of water molecules by ultraviolet light –Produced O2 levels approx. 1-2% current levels At these levels O3 (Ozone) can form to shield Earth surface from UV Photosynthesis - CO2 + H2O + sunlight = organic compounds + O2 –produced by cyanobacteria, and eventually higher plants –supplied the rest of O2 to atmosphere. Thus plant populations

25. Cyanobacteria that fixes CO2 to release O2

27.  99% of the atmosphere is within 20 miles of the Earth’s surface  N 2 78% and O 2 21%  The percentages represent a constant amount of gas but cycles of destruction and production are constantly maintaining this amount

29.  Water is a variable, but very important gas ◦ The hydrologic cycle: evaporation, precipitation, runoff, etc.  Carbon dioxide concentrations have risen in recent years ◦ CO 2 is an important greenhouse gas, though not the only one  Ozone: “Good up high, bad nearby”

30.  Lower in summer when plants are active and absorb CO 2  Has risen more than 20% since 1958

31. Stepped Art Fig. 1-4, p. 7

33.  Near the ground, ozone is the main ingredient in smog, irritant to eyes; plants  In the stratosphere, ozone provides a protective shield from ultraviolet radiation  This protective shield erodes over Antarctica in their winter, causing a stratospheric “ozone hole” Low concentrations of ozone over Antarctica, September 2004

34.  Weather: short term air temperature, air pressure, humidity, clouds, precipitation, visibility, and wind  Climate: long term patterns and average weather; not just magnitude but also frequency.  But climate is not just the average, it also describes the range of possibilities

35.  Atmospheric Pressure  Temperature  Moisture ◦ Water vapor in the air ◦ Precipitation  Wind ◦ Direction ◦ Speed

36.  Atmospheric Pressure is the force per unit area of a column of air above you (extending all the way to the “top” of the atmosphere)  In other words, pressure is the weight of the column of air above you - a measure of how hard this column of air is pushing down  More fundamentally - atmospheric pressure arises from gravity acting on a column of air

37.  Molecules bumping into an object create a force on that object  Pressure is the force applied per unit area ◦ P = F/A ◦ Which box below is exerting the greatest pressure upon the ground? Force = mass x gravity 1 kg

38.  Pressure is one of the most fundamental forces which produces weather and makes our atmosphere move – the wind!  Pressure defines many of our most important weather patterns: midlatitude cyclones, hurricanes, anticyclones  Pressure is usually in units of millibars (mb), though sometimes in inches of Mercury (in Hg) ◦ Barometers with mercury in them can be used to measure pressure ◦ Typical pressure at sea level is 1013.25 mb, or 29.92 in Hg

39.  Density = mass / volume  Denser air displaces less dense air - just like water displaces air  Lower-density air rises when it is surrounded by denser air - one of the primary forces which produces vertical motions in the atmosphere ◦ Think of a ping-pong ball submerged under water. What happens when you release it? 1 kg Which box is more dense?

41.  Most of the air is near the ground  At an altitude of 5.5 km (about 18000 ft), you are above 50% of the air in the atmosphere. At 50000 ft, you are above 90% of the air!

42. Fig. 1.16, p. 19

43.  Temperature is a measure of the kinetic (motion) energy of air molecules ◦ K.E. = ½ mv 2 m = mass, v = velocity ◦ So…temperature is a measure of air molecule speed  The sensation of warmth is created by air molecules striking and bouncing off your skin surface ◦ The warmer it is, the faster molecules move in a random fashion and the more collisions with your skin per unit time

46. Mr. Hartwell -- F-M Meteorology Earth’s Atmosphere * Structure * http://apollo.lsc.vsc.edu/classes /met130/notes/ http://apollo.lsc.vsc.edu/classes /met130/notes/

47. Recall from Earth Science… Diagram NOT to scale

48. Vertical Structure of Atmos. Meteorological variables that define layers of the atmosphere: –Density –Pressure –Temperature How do each change with increasing altitude?

49. Density decreasesDensity (mass/volume) decreases with height

50. Pressure decreasesPressure (force/area) decreases with height in the atmosphere

51. Pressure Q: Which exerts more pressure? –4000lb elephant standing on one leg with foot size of 8”x8” –120 lb woman standing on one leg in high-healed shoes with a heal size of 1”x1”

52. Temperature Temperature in the atmosphere decreases + increases with height Temperature changes denote atmospheric layers: –Troposphere –Stratosphere –Mesosphere –Thermosphere

55. Troposphere 0 km (surface) – 12 km altitude 75% of atmosphere All weather takes place here ‘-pause’—boundary between layers jet streamTroposphere—contains the jet stream —lid on the weather

58. Stratosphere 12 km – 50 km altitude Contains the Ozone Layer Ozone Layer—atmospheric shield for Earth’s surface –Absorbs UV light; temps. increase in strat.

60. Other atmospheric layers Mesosphere 50 km – 80 km altitude Shields Earth from meteoroids Thermosphere +80 km altitude High heat; UV energy turned to heat Contains the Ionosphere & Exosphere

62.  Red line shows temperature  Temperature decreases with height in troposphere and mesosphere; increases with height in thermosphere

63.  The change in temperature with height is called the lapse rate  In the troposphere, on average, the temperature decreases 6.5° Celsius for every kilometer that you go up  Sometimes, though, it’s the opposite: when temperature increases with height, it is called an inversion  If temperature is constant with height: isothermal (iso=same, thermal=temperature)

64.  Electrified region of the thermosphere (not really a layer)  The ionosphere extends from approximately 60 km above ground to the top of the atmosphere  Three regions within the ionosphere: D, E, and F  The “D” region absorbs AM radio waves, but it disappears at night.  The “E” and “F” regions reflect AM waves back toward the ground  This is why you can often hear AM stations from all over the country at night

65.  Moving air – determines many aspects of the weather  Wind is the atmosphere’s response to pressure differences  We care about both the wind speed and direction  Units: ◦ Meters per second (m/s) ◦ Miles per hour (mph) ◦ Nautical miles per hour (knots)  1 meter/second = 2.24 miles/hour = 1.94 knots  A hurricane has sustained winds greater than 74 mph, or 64 knots, or 33 m/s

66. Wind Direction N 0 o or 360 o E 90 o S 180 o W 270 o 45 o 135 o 225 o 315 o In meteorology, we describe the wind in terms of where it is coming from So, a “west wind” blows from west to east

67. Fig. 1.17, p. 20 Scales of Motion Examples Most meteorologists refer to this as the synoptic scale. Or, the size of a large thunderstorm or cluster of storms.

68.  Moisture ◦ Clouds and precipitation are associated with surface low pressure; clear skies with surface high pressure. ◦ Relative humidity does not tell us how much water vapor is actually in the air; rather, it tells us how close the air is to being saturated. ◦ The dew point temperature is the temperature to which air would have to be cooled in order for saturation to occur.

69. Fig. 1.20, p. 21

70. Fig. 1.21, p. 22

71. Fig. 1.22, p. 22

72. Fig. 1.23, p. 24

73.  Wind chill  Drought  Heat waves  Tornadoes (cyclones, twisters)  Thunderstorms (lightening, flash floods, downburst)  Mid-latitude cyclones  Hurricanes

74. Fig. 1.24, p. 26

75. Fig. 1.25, p. 27

76. Fig. 1.26, p. 28

77. Fig. 1.27, p. 29

78. Fig. 1.28, p. 29

79. Fig. 1.29, p. 30

80. Fig. 1.30, p. 30

81.  Surface observing stations ◦ Mostly at airports, but now also at schools, along highways, etc. ◦ Describe conditions near the ground---temperature, humidity, winds, precipitation, etc. ◦ Some are recorded by people, others automated ◦ Used by many people: pilots, farmers, weather forecasters, and the public!

82.  Upper-air observations ◦ Weather balloons are launched twice a day from locations around the world ◦ Attached to the balloons is an instrument called a “radiosonde” ◦ This measures the temperature, pressure, humidity, and winds ◦ The vertical structure is also measured by satellites and ground-based instruments ◦ The hurricane hunter airplanes use “dropsondes”: instead of a balloon going up, the instruments are on a parachute going down  There isn’t a station very close to here…the surrounding stations are in Binghamton, NY

83. Movie Clip of Downsondes

84.  http://www.weather.gov/data/obhistory/KSY R.html http://www.weather.gov/data/obhistory/KSY R.html

85. Tropopause

86. Inversion (temperature increases with height)