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Tonight February 8 Weather Review Weather Review Weather map basics Weather map basics Energy that Drives the Storms (chapter 2) Energy that Drives the.

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Presentation on theme: "Tonight February 8 Weather Review Weather Review Weather map basics Weather map basics Energy that Drives the Storms (chapter 2) Energy that Drives the."— Presentation transcript:

1 Tonight February 8 Weather Review Weather Review Weather map basics Weather map basics Energy that Drives the Storms (chapter 2) Energy that Drives the Storms (chapter 2) More Weather Maps (Isopleths) More Weather Maps (Isopleths) Classwork (HW#3) Classwork (HW#3) Homework #4 Homework #4

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3 Weather Preview What is the forecast for next week? What is the forecast for next week? Monday? Monday? Tuesday? Tuesday? Wednesday? Wednesday? During the course of the week try and keep track if the forecast During the course of the week try and keep track if the forecast Changes? Changes? Is accurate? Is accurate?

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5 Weather Symbols and Maps

6 Station model

7 Weather Symbols

8 Sky Symbols

9 Wind Symbols

10 Pressure Tendency

11 Station model

12 Temperature Surface: ºF Upper air: ºC

13 Station model Dew point temperature Surface: ºF Upper air: ºC

14 Station model Total sky cover ** Depicted by shading in circle

15 Station model Current weather conditions ** If blank, “no weather”

16 Station model Wind direction – of wind toward center

17 Station model Wind speed Long barb = 10 knots Short barb = 5 knots Flag = 50 knots ** Notice range of wind speeds (i.e., knots)

18 Station model Sea level pressure **If first number is 5 or greater, then place 9 in front --Otherwise, place 10 in front --Otherwise, place 10 in front **Place decimal point between last two numbers

19 Station model Change in surface pressure during last 3 hours ** In tenths of mb ** Line describes how pressure changes over time from left to right

20 Example 1 Temperature: 76 ºF Temperature: 76 ºF Dew point: 65 ºF Dew point: 65 ºF Sky cover: Completely overcast Sky cover: Completely overcast Current weather: Light rain Current weather: Light rain Wind direction and speed: Southwest at 15 knots Wind direction and speed: Southwest at 15 knots Sea level pressure: mb Sea level pressure: mb Pressure tendency: Increase of 1.6 mb; rising steadily Pressure tendency: Increase of 1.6 mb; rising steadily

21 Example Temperature: 10ºFTemperature: 10ºF Dew point: 8ºFDew point: 8ºF Sky cover: 7/10 or 8/10Sky cover: 7/10 or 8/10 Current weather: Snow showerCurrent weather: Snow shower Wind direction and speed: North at 3-7 knotsWind direction and speed: North at 3-7 knots Sea level pressure: mbSea level pressure: mb Pressure tendency: Decrease of 0.4 mb; falling, then steadyPressure tendency: Decrease of 0.4 mb; falling, then steady

22 High & Low Pressure Systems °Air pressure Patterns are main organizing feature °Circulation in Northern Hemisphere °Clockwise around Highs (H) °CCW around Lows (L) °Clouds & Precip around Lows °Temperature patterns result from latitude, wind flow and cloud cover

23 Plotting Fronts °Boundary between Different Air Masses °Types of Fronts

24 Weather Maps

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32 CHAPTER 2 ENERGY THAT DRIVES THE STORMS CHAPTER 2 ENERGY THAT DRIVES THE STORMS

33 ENERGY AND HEAT TRANSFER Energy is the capacity to do work on some form of matter – Potential energy: The total amount of energy stored in any object is capable of doing – Kinetic energy: Any moving substance possesses energy of motion

34 Fig. 2.1, p. 37 Cold Air vs. Warm Air Slower and closer together ….. Faster and farther apart

35 ENERGY AND HEAT TRANSFER Atoms and molecules have kinetic energy due to their motion (heat energy) Sun’s radiant energy most important Air temperature is a measure of the average kinetic energy of its molecules

36 ENERGY AND HEAT TRANSFER Heat = energy transferred because of a temperature difference After heat is transferred, it is stored as internal energy Heat is transferred in the atmosphere by – Conduction – Convection – Radiation

37 ENERGY AND HEAT TRANSFER Latent heat: energy required to change a substance, such as water, from one state to another Evaporation = cooling process, absorption of latent heat from the environment Condensation = warming process, release of latent heat to the environment

38 Fig. 2.2, p. 37 Changes of State

39 ENERGY AND HEAT TRANSFER Conduction: the transfer of heat from molecule to molecule – Always flows from warmer to colder – Air is an extremely poor conductor of heat

40 ENERGY AND HEAT TRANSFER Convection = heat transfer by the mass movement of a fluid (water or air) – Example: Pan of boiling water Convection circulation: warm air expands and rises then cools and sinks – Thermal cell, convection, thermals

41 Fig. 2.5, p. 40 Thermal Circulations

42 Fig. 2.6, p. 40 Thermal Circulations

43 ENERGY AND HEAT TRANSFER Radiation = Energy transfer via electromagnetic waves Radiation and Temperature – Hotter objects Emit shorter wavelengths Emit radiation at a greater rate or intensity

44 Fig. 2.7, p. 41 Electromagnetic Radiation

45 ENERGY BALANCING ACT Radiation of the Sun and Earth – Sun (6000 K) emits mostly shortwave radiation – Earth emits mostly longwave radiation

46 Fig. 2.8, p. 44 SUN’S ELECTROMAGNETIC SPRECTRUM Mostly shorter wavelengths

47 Fig. 2.9, p. 44 SUN EARTH Electromagnetic Radiation

48 ENERGY BALANCING ACT Selective Absorbers: – Good absorbers are good emitters at a particular wavelength, and vice versa. – Greenhouse effect: the atmosphere selectively absorbs infrared radiation from the Earth’s surface but acts as a window and transmits shortwave radiation

49 Fig. 2.10, p. 46 Atmospheric Absorption of Radiation

50 A GREENHOUSE Glass is transparent to short visible wavelengths (SW) but opaque to long infrared (LW) wavelengths. Glass is transparent to short visible wavelengths (SW) but opaque to long infrared (LW) wavelengths.

51 w/o GREENHOUSE GASES

52 w/ GREENHOUSE GASES

53 ENERGY BALANCING ACT Greenhouse Enhancement – Global warming is occurring due to an increase in greenhouse gases Carbon dioxide, methane, nitrogen oxide, chloroflourocarbons (CFCs), ozone – Positive feedbacks continue the warming trend. – Negative feedbacks decrease warming.

54 Positive Feedback When the response in a second variable reinforces the change in the initial variable When the response in a second variable reinforces the change in the initial variable Example of positive feedback: Example of positive feedback: – Global temperatures increase – Increase in temperature melts the ice and snow in the upper latitudes – Loss of ice and snow results in a lower albedo at the surface in the upper latitudes – Lower albedo leads to less reflection and more insolation – More insolation results in warmer temperatures

55 Negative Feedback When the response in a second variable lessens the change caused by the initial variable When the response in a second variable lessens the change caused by the initial variable Example of negative feedback: Example of negative feedback: – Global warming leads to more atmospheric water vapor – Increased water vapor leads to increased cloud cover – Increased cloud cover leads to a higher albedo – Higher albedo results in less insolation at the surface – Reduced insolation at the surface leads to cooling

56 Fig. 2.13, p. 50 Solar Radiation

57 ALBEDO Percent of sunlight reflected from clouds and earth surfacesPercent of sunlight reflected from clouds and earth surfaces Earth average albedo = 30%Earth average albedo = 30% Surface Albedo (%) Earth and Atmosphere30 Clouds (Thick)60-90 Clouds (Thin)30-50 Fresh Snow75-95 Ice30-40 Sand15-45 Grassy Field10-30 Plowed Field5-20 Water10 Moon7

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59 Fig. 2.14, p. 51 Atmospheric Energy Balance

60 Fig. 2.15, p. 52 Global Energy Balance

61 ENERGY BALANCE

62 WHY THE EARTH HAS SEASONS Earth revolves in elliptical path around sun every 365 days. Earth rotates counterclockwise or eastward every 24 hours. Earth closest to sun (147 million km) in January, farthest from sun (152 million km) in July. Distance not the only factor impacting seasons.

63 Fig. 2.16, p. 52 Elliptical Orbit

64 Fig. 2.17, p. 53 Sun Angle

65 WHY THE EARTH HAS SEASONS Energy reaching the earth’s surface, result of: – Distance from the sun – Solar angle – Length of daylight. Earth tilted toward the sun: – Higher solar angles and longer days

66 Fig. 2.20, p. 56 Sun Angle

67 Fig. 2.18, p. 53 Sun and the Seasons

68 WHY THE EARTH HAS SEASONS Seasons in the Northern Hemisphere – Summer solstice: ~ June 21 Sun directly above Tropic of Cancer (23.5° N) Longer days in N Hemisphere – Winter solstice: ~ December 21 Sun directly above Tropic of Capricorn (23.5° S) Shorter days in N Hemisphere – Autumnal and Vernal Equinox: ~ Sep 22, Mar 20 Sun directly above Equator All locations have a 12 hour day

69 Table 2.3, p. 57

70 Stepped Art Fig. 2.22, p. 58 Sun’s Seasonal Path

71 Fig. 2.19, p. 56 Sun’s Seasonal Path

72 WHY THE EARTH HAS SEASONS Seasons in the Southern Hemisphere – Opposite timing of N Hemisphere – Closer to sun in summer but not significant difference

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74 ISOPLETHS

75 Contour Maps

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78 ISOBARS

79 ISOTHERMS

80 ISOTACHS

81 ISOHYET

82 ISOPLETHS °Connects all points that have the same value °Iso = equal (Greek) °Also called “Isolines” °Types °Isobar = pressure °Isallobar = pressure change per time °Isotherm = temperature °Isohyet = rainfall °Isonif = snowfall °Isoryme = frost incidence °isoneph = cloudiness °isotach = wind speed

83 ISOPLETHS (cont’d) °Rules °Only through exact value of isopleth °Higher side and lower side °All higher should be on the same side of the line °Draw for all values °Spacing by interpolation °Spacing indicates rate of change (I.e., gradient) °Isopleths form closed loops °Isopleth never cross one another

84 ISOPLETHS (cont’d) DRAWING HINTS DRAWING HINTS – Note location of lowest and highest values – Begin around these low or high values and gradually work outward – Sketch lightly to get spacing and orientation of – Smooth the isopleths. Isopleths generally do not have sharp bends

85 ISOPLETHS Draw 6.5 contour

86 ISOPLETHS

87 ISOPLETHS Draw even contours

88 ISOPLETHS

89 ISOTHERMS Draw 10, 20, 30,40, 50, 60, 70 degree contours

90 ISOTHERMS

91 Isodrosotherms

92 Isodrosotherms

93 HOMEWORK #4 Draw Isotherms at 10 degree intervals( i.e., 50, 60, 70, 80, 90 degrees). Due next week (2/15/11) at the beginning of class.


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