This slid for Atmosphere hazards-Climatology Chapter

1. Atmospheric HazardsAtmospheric Hazards
Thunderstorms, Tornadoes,Thunderstorms, Tornadoes,
High Winds, and FogHigh Winds, and Fog
Session 7Session 7

2. Pure AirPure Air
 InvisibleInvisible
 ColorlessColorless
 OdorlessOdorless
 TastelessTasteless

3. Atmospheric CompositionAtmospheric Composition
 GasesGases
 Liquid and Solid MatterLiquid and Solid Matter

4. Atmospheric GasesAtmospheric Gases
 Nitrogen 78% of volumeNitrogen 78% of volume
 Oxygen 21%Oxygen 21%
 Others combined approximately 1%Others combined approximately 1%
 Includes Argon, Neon, Helium,Includes Argon, Neon, Helium,
Methane, Krypton, and HydrogenMethane, Krypton, and Hydrogen

5. Variable-Amount GasesVariable-Amount Gases
 Water VaporWater Vapor
 Carbon dioxideCarbon dioxide
 Carbon MonoxideCarbon Monoxide
 OzoneOzone
 Sulfur dioxideSulfur dioxide
 Nitrogen dioxideNitrogen dioxide

6. Atmospheric CompositionAtmospheric Composition

7. Liquid and Solid MatterLiquid and Solid Matter
 Liquid: WaterLiquid: Water
 < 1% by volume< 1% by volume
 Solids: Ice CrystalsSolids: Ice Crystals
 < 1% by volume< 1% by volume
 Particulate matterParticulate matter
 < 1% by volume< 1% by volume

8. Particulate MatterParticulate Matter
 Tiny solids such as dust, smoke, soil,Tiny solids such as dust, smoke, soil,
ash, salt spray, and pollutantsash, salt spray, and pollutants
 May be suspended in the atmosphereMay be suspended in the atmosphere
for long periods of time (years)for long periods of time (years)
 Most particulate matter close toMost particulate matter close to
source of origin but can travel greatsource of origin but can travel great
distances both horizontally anddistances both horizontally and
verticallyvertically

9. Affects on WeatherAffects on Weather
 Hygroscopic (absorb water) so waterHygroscopic (absorb water) so water
vapor condenses around particulatesvapor condenses around particulates
affecting cloud formationaffecting cloud formation
 Absorb or reflect insolation changingAbsorb or reflect insolation changing
the amount of solar radiationthe amount of solar radiation
reaching the surfacereaching the surface

10. Atmospheric PressureAtmospheric Pressure
 Atmosphere has weight, pressingAtmosphere has weight, pressing
downwarddownward
 Molecules of air create air pressureMolecules of air create air pressure
through their motion, size, andthrough their motion, size, and
numbernumber
 Pressure exerted on all surfaces inPressure exerted on all surfaces in
contact with the aircontact with the air
 Same pressure inside us pushingSame pressure inside us pushing
outward so we are not crushedoutward so we are not crushed

11. More PressureMore Pressure
 Average force 14.7 lb/in.Average force 14.7 lb/in.22
 Normal pressure 1013.2 mb (29.92”)Normal pressure 1013.2 mb (29.92”)
 Density decreases with altitudeDensity decreases with altitude
 50% of molecules are below 3.550% of molecules are below 3.5
miles and 90% in 10 milesmiles and 90% in 10 miles

12. Thermal LayersThermal Layers
 TroposphereTroposphere
 StratosphereStratosphere
 MesosphereMesosphere
 ThermosphereThermosphere
 ExosphereExosphere

13. Layers of the AtmosphereLayers of the Atmosphere

14. TroposphereTroposphere
 Lowest region of the atmosphereLowest region of the atmosphere
 Name implies vertical mixing of airName implies vertical mixing of air
 Usually a steady decrease inUsually a steady decrease in
temperature with an increase intemperature with an increase in
altitudealtitude
 3.53.5° per 1000’ (6.4°/1000m)° per 1000’ (6.4°/1000m)
 Lapse RateLapse Rate

15. InversionsInversions
 Increase in air temperature withIncrease in air temperature with
increase in altitudeincrease in altitude
 Can trap air pollutionCan trap air pollution

16. Tropospheric CharacteristicsTropospheric Characteristics
 Most moisture and heat located hereMost moisture and heat located here
 Most weather occursMost weather occurs
 Depth an average of 11 miles fromDepth an average of 11 miles from
surface at equator and 5 miles at thesurface at equator and 5 miles at the
polespoles
 Fluctuates during seasonsFluctuates during seasons

17. StratosphereStratosphere
 Roughly 11 miles to 31 miles aboveRoughly 11 miles to 31 miles above
the surfacethe surface
 Strong inversion exists due toStrong inversion exists due to
absorption of uv radiation from theabsorption of uv radiation from the
SunSun
 Contains ozone (OContains ozone (O33) layer to absorb) layer to absorb
this radiationthis radiation
 Transition zone called stratopauseTransition zone called stratopause

18. MesosphereMesosphere
 Temperature decreases with heightTemperature decreases with height
 Due to distance from ozone layerDue to distance from ozone layer
 Approximately 31 to 50 miles aboveApproximately 31 to 50 miles above
the Earth’s surfacethe Earth’s surface
 Top of layer bounded by anTop of layer bounded by an
isothermal layer called theisothermal layer called the
MesopauseMesopause

19. ThermosphereThermosphere
 Dramatic decrease in heat energy contentDramatic decrease in heat energy content
 BUT very high temperature (2200BUT very high temperature (2200° F)° F)
 Due to lack of massDue to lack of mass
 Approximately 50 to 300 miles above theApproximately 50 to 300 miles above the
Earth’s surface (lower in less active solarEarth’s surface (lower in less active solar
activity, 155 miles)activity, 155 miles)
 Isothermal layer called the ThermopauseIsothermal layer called the Thermopause

20. ExosphereExosphere
 300 miles out to 20,000 miles from300 miles out to 20,000 miles from
the surfacethe surface
 Outer spaceOuter space
 Atmosphere is rarefied, practically aAtmosphere is rarefied, practically a
vacuumvacuum
 Few hydrogen and helium atomsFew hydrogen and helium atoms
weakly bound by gravityweakly bound by gravity

21. What is Weather?What is Weather?

22. WeatherWeather
 Short term atmospheric conditions thatShort term atmospheric conditions that
exist for a given time in a specific locationexist for a given time in a specific location
 Can be sum of variables such asCan be sum of variables such as
temperature, cloudiness, humidity,temperature, cloudiness, humidity,
precipitation, wind, storms, and pressureprecipitation, wind, storms, and pressure
 Temporal parameters can be moment,Temporal parameters can be moment,
day, week, season, year, or decadeday, week, season, year, or decade

23. What is Climate?What is Climate?

24. ClimateClimate
 Aggregate of day-to-day weatherAggregate of day-to-day weather
conditions over a long period of timeconditions over a long period of time
 Includes both average characteristicsIncludes both average characteristics
along with the variations andalong with the variations and
extremesextremes
 Normally 30 years for climate studiesNormally 30 years for climate studies

25. Major Elements of Weather andMajor Elements of Weather and
ClimateClimate
 TemperatureTemperature
 PressurePressure
 WindWind
 Moisture ContentMoisture Content

26. Principal Climate and WeatherPrincipal Climate and Weather
ControlsControls
 LatitudeLatitude
 Land and water distributionLand and water distribution
 General circulation of theGeneral circulation of the
atmosphereatmosphere
 General circulation of the oceansGeneral circulation of the oceans
 ElevationElevation
 Topographic barriersTopographic barriers
 StormsStorms

27. LatitudeLatitude
 Latitude influences temperatureLatitude influences temperature
 Positional relationship between EarthPositional relationship between Earth
and Sunand Sun
 Varying amounts of radiant energyVarying amounts of radiant energy

28. Land and Water DistributionLand and Water Distribution
 Moisture content and temperatureMoisture content and temperature
 Continental versus maritime climatesContinental versus maritime climates
 Oceans heat and cool slower thanOceans heat and cool slower than
landmasseslandmasses
 Source of moistureSource of moisture
 Uneven distribution of land andUneven distribution of land and
waterwater

29. General Circulation of theGeneral Circulation of the
AtmosphereAtmosphere
 Semipermanent pattern of wind andSemipermanent pattern of wind and
pressure systems in the tropospherepressure systems in the troposphere
 Local wind to regional patternsLocal wind to regional patterns
 Winds in the tropics from east whileWinds in the tropics from east while
midlatitudes from westmidlatitudes from west

30. General Circulation of theGeneral Circulation of the
OceansOceans
 Heat transfer with currentsHeat transfer with currents
 Warm water poleward and cool waterWarm water poleward and cool water
towards the equatortowards the equator
 Warm currents off east coasts ofWarm currents off east coasts of
continentscontinents
 Cool currents off west coasts ofCool currents off west coasts of
continentscontinents

31. ElevationElevation
 Temperature, pressure, and moistureTemperature, pressure, and moisture
content decrease with increase incontent decrease with increase in
elevationelevation
 Influence in mountainous areasInfluence in mountainous areas

32. Topographic BarriersTopographic Barriers
 Mountains and hills have effects onMountains and hills have effects on
climate elementsclimate elements
 Lake effect snowLake effect snow
 Windward and leeward side ofWindward and leeward side of
mountainsmountains

33. StormsStorms
 Local thunderstormLocal thunderstorm
 TornadoTornado
 HurricaneHurricane
 MonsoonMonsoon
 BlizzardBlizzard
 Mid Latitude CycloneMid Latitude Cyclone

34. What are the CharacteristicsWhat are the Characteristics
of a Thunderstorm?of a Thunderstorm?

35. ThunderstormsThunderstorms
 Heavy rainHeavy rain
 LightningLightning
 Flash FloodingFlash Flooding
 HailHail
 WindWind
 TornadoesTornadoes

36. What is a Severe Thunderstorm?What is a Severe Thunderstorm?

37. Severe ThunderstormsSevere Thunderstorms
 Winds > 50 kts (58 mph)Winds > 50 kts (58 mph)
 HailHail ≥ 1”≥ 1”
 TornadoTornado

38. Life CycleLife Cycle
 Three Main StagesThree Main Stages
 InitialInitial
 MatureMature
 DissipationDissipation

39. Initial StageInitial Stage
 Towering Cumulus StageTowering Cumulus Stage
 Persistent updraft and rapidlyPersistent updraft and rapidly
growing vertical cloudgrowing vertical cloud
 Expanding cloud diameterExpanding cloud diameter

40. Mature StageMature Stage
 Updraft strength reaches maximumUpdraft strength reaches maximum
heightheight
 Some storm tops over 25,000’-Some storm tops over 25,000’-
60,000’ agl60,000’ agl
 Lightning at beginning of matureLightning at beginning of mature
stagestage
 Rainfall begins and forces downdraftRainfall begins and forces downdraft
 MicroburstsMicrobursts
 HailHail
 Gust frontGust front
 Pool of cool air at surfacePool of cool air at surface

41. Dissipation StageDissipation Stage
 Dome of cool air cuts off updraft atDome of cool air cuts off updraft at
surface and causes storm to die outsurface and causes storm to die out
 Edge of dome is now in outflowEdge of dome is now in outflow
boundary, potential for newboundary, potential for new
thunderstorms to formthunderstorms to form
 Possible tornado formation due toPossible tornado formation due to
enhanced low-level horizontal shearenhanced low-level horizontal shear

42. Thunderstorm StagesThunderstorm Stages

43. Types of ThunderstormsTypes of Thunderstorms

44. Forms of ThunderstormsForms of Thunderstorms
 Squall Line: organized line ofSquall Line: organized line of
individual cells (downbursts,individual cells (downbursts,
straight-line winds)straight-line winds)
 Multicell Cluster (MCC): strongMulticell Cluster (MCC): strong
updrafts (hail, heavy precipitation);updrafts (hail, heavy precipitation);
can exist for hourscan exist for hours
 Supercell: strong updrafts andSupercell: strong updrafts and
vertical wind shear (potentialvertical wind shear (potential
mesocyclones and tornadoes); largemesocyclones and tornadoes); large
hail and downburstshail and downbursts

45. SupercellSupercell

46. Thunderstorm DistributionThunderstorm Distribution

47. Lightning FatalitiesLightning Fatalities

48. Thunderstorm Case StudiesThunderstorm Case Studies
 Nashville, TennesseeNashville, Tennessee
 Ouachita National Forest, ArkansasOuachita National Forest, Arkansas

49. Nashville, TennesseeNashville, Tennessee
 May 1-2, 2010May 1-2, 2010
 13+” rain13+” rain
 29 fatalities in southern United29 fatalities in southern United
StatesStates
 http://www.srh.noaa.gov/ohx/?n=may2http://www.srh.noaa.gov/ohx/?n=may2

50. Ouachita National ForestOuachita National Forest
 June 11, 2010June 11, 2010
 5+” rain5+” rain
 River estimated to rise 8’/hourRiver estimated to rise 8’/hour
 20 fatalities20 fatalities

51. TornadoesTornadoes
 Rapidly rotating column of air thatRapidly rotating column of air that
extends from cloudbase to groundextends from cloudbase to ground
 InvisibleInvisible
 Primarily produced by mesocyclonesPrimarily produced by mesocyclones

52. Tornado LifecycleTornado Lifecycle
 Dust WhirlDust Whirl
 OrganizingOrganizing
 MatureMature
 WeakeningWeakening
 RopeRope

53. Tornado FormationTornado Formation

54. Tornado DistributionTornado Distribution

55. Tornadoes by MonthTornadoes by Month

56. Tornadoes by Time of DayTornadoes by Time of Day

57. Enhanced Fujita ScaleEnhanced Fujita Scale
FF
ScaleScale
Wind SpeedWind Speed EF-EF-
ScaleScale
WindWind
SpeedSpeed
F0F0 45-7845-78 EF0EF0 65-8565-85
F1F1 79-11779-117 EF1EF1 86-10986-109
F2F2 118-161118-161 EF2EF2 110-137110-137
F3F3 162-209162-209 EF3EF3 138-167138-167
F4F4 210-261210-261 EF4EF4 168-199168-199
F5F5 262-317262-317 EF5EF5 200-234200-234
Wind speeds in mph, 3-second gust

58. Number of Tornadoes by F-ScaleNumber of Tornadoes by F-Scale

59. F5 Tornadoes in the U.S.F5 Tornadoes in the U.S.

60. Fatalities by DecadeFatalities by Decade
D ec ade T or nado es/Y ear F at alit ies/ Year
1 95 0-5 9 4 8 0 1 4 8
1 96 0-6 9 6 8 1 9 4
1 97 0-7 9 8 5 8 1 0 0
1 98 0-8 9 8 1 9 5 2
1 99 0-9 9 1 ,2 20 5 6
2 00 0-0 7 1 ,3 19 5 2
N o te: 2 000 -200 7 i s l es s t ha n a d e cad e.

61. Tornado Cases StudiesTornado Cases Studies
 Tristate Tornado OutbreakTristate Tornado Outbreak
 Xenia, OhioXenia, Ohio
 Moore, Oklahoma (Oklahoma City)Moore, Oklahoma (Oklahoma City)

62. Tristate TornadoTristate Tornado

63. Xenia, OhioXenia, Ohio
 April 3, 1974April 3, 1974
 34 fatalities34 fatalities
 1150 injuries1150 injuries
 2000+ homes2000+ homes

64. Moore, OklahomaMoore, Oklahoma
 Adjacent to Oklahoma CityAdjacent to Oklahoma City
 May 3, 1999May 3, 1999
 38 fatalities38 fatalities
 800 injuries800 injuries

65. Horizontal Movement of AirHorizontal Movement of Air
 Wind: Horizontal movement of airWind: Horizontal movement of air
 Larger spatial area than verticalLarger spatial area than vertical
motionmotion
 ““Air in a hurry”Air in a hurry”

66. Ultimate Cause of Wind?Ultimate Cause of Wind?

67. AnswerAnswer
 InsolationInsolation
 Unequal heating of EarthUnequal heating of Earth
 Temperature and pressure gradientsTemperature and pressure gradients
put air in motionput air in motion
 Nature’s way to move air pressure toNature’s way to move air pressure to
form an equilibriumform an equilibrium

68. Main Causes of Wind DirectionMain Causes of Wind Direction
 Pressure GradientPressure Gradient
 Coriolis EffectCoriolis Effect
 FrictionFriction

69. Pressure GradientPressure Gradient

70. Coriolis EffectCoriolis Effect

71. Wind Direction VariablesWind Direction Variables

72. Wind DirectionWind Direction
 Direction from which wind is blowingDirection from which wind is blowing
 Measured in degreesMeasured in degrees
 00°=North°=North
 90°=East90°=East
 180°=South180°=South
 270°=West270°=West

73. Wind SpeedWind Speed
 Knots (1 nautical mile per hour)Knots (1 nautical mile per hour)
 MPH (1kt = 1.15 mph)MPH (1kt = 1.15 mph)
 m/s (1 kt = 0.51 m/s)m/s (1 kt = 0.51 m/s)
 Average wind speed in U.S. 6.9-13.8Average wind speed in U.S. 6.9-13.8
mphmph

74. Wind Case StudiesWind Case Studies
 Schmidlin articleSchmidlin article
 Santa Ana winds and wildfires inSanta Ana winds and wildfires in
CaliforniaCalifornia

75. FogFog
 According to international definition,According to international definition,
fog reduces visibility below 1 kmfog reduces visibility below 1 km
(0.62 miles)(0.62 miles)
 Fog differs from a cloud only in thatFog differs from a cloud only in that
the base of fog is at the Earth’sthe base of fog is at the Earth’s
surface while clouds are above thesurface while clouds are above the
surfacesurface

76. Fog FormationFog Formation
 CoolingCooling
 Evaporation and mixingEvaporation and mixing

77. Major Fog TypesMajor Fog Types
 RadiationRadiation
 AdvectionAdvection
 UpslopeUpslope

78. Types of Fog in U.S.Types of Fog in U.S.

79. Days with Heavy FogDays with Heavy Fog

80. Fog HazardsFog Hazards
 Problems due to reduced visibilityProblems due to reduced visibility
 Transportation sector: vehicle,Transportation sector: vehicle,
maritime, and aviation accidentsmaritime, and aviation accidents
 Health issues: smog and acid fogHealth issues: smog and acid fog

81. Fog Case StudiesFog Case Studies
 Maritime: Andrea Doria, 1956, 46Maritime: Andrea Doria, 1956, 46
fatalitiesfatalities
 Aviation: B-25 crash into EmpireAviation: B-25 crash into Empire
State Building, 1945, 14 fatalitiesState Building, 1945, 14 fatalities
 Vehicles: Calhoun, Tennessee, 1990,Vehicles: Calhoun, Tennessee, 1990,
99 vehicles, 12 deaths, 42 injuries99 vehicles, 12 deaths, 42 injuries

82. Fog AccidentsFog Accidents
 40,000+ fog-related crashes per40,000+ fog-related crashes per
yearyear
 600 fatalities and 19,000+ injuries600 fatalities and 19,000+ injuries
annuallyannually