Intro to Meteorol
Intro to Meteorol ATSC 2000
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General Circulation of the atmosphere Represents quotaverage air ow around the globe is created by unequal heating at earth39s surface Recall On global scale earth is in radiative equilibrium energy in equals energy out this is not true however at each latitude general circulation39s function is to transport heat pole ward SingleCell Model of the General Circulation If you assume earth is uniformly covered with water sun is directly over equator no rotation You will end up with a singlecell pattern gtgt called the Hadley Cell warm air rises at the equator cold air sinks at the poles W m NgdlzLell t I a V Wm mu mum m m u ThreeCell Model of the General Circulation Threecells Hadley cell Ferrel Cell Polar Cell Surface pressure High and low pressure bands Surface winds Westerlies Trade winds ITCZ comparison to real wor d7 Satellites provide a global picture of winds over the oceans by converting sea roughness into wind speed and direction m Mum Cloud movement can tell you global wind movement hrtn39llwww nrlmrv naw mi at kink kn39 rni Observed average surface pressure and winds during January Semipermanent pressure areas BermudaAzores High Pacific High Aleutian Low 7 genesis region for cyclones Impacting the Paci c NW 39 Icelandic Low Seasonal pressure areas Siberian High Canadian High Observed average surface pressure and winds during July Semi permanent pressure areas Bermud Azores High Pacific High Iclandic Low Seasonal pressure areas Monsoon Low Thermal Low rm over SW US WWW A winter weather map depicting the main features of the general circulation over North America Notice that the Canadian high polar front and subpolar lows have all moved southward into the United States and that the prevailing westerlies exist south of the polar front The arrows on the map illustrate wind direction vallli l bl rmrlm Global Precipitation Pattern Produced by the General Circulation Zonal distribution of preCIpitation around the globe rough y akin 0 N low pressure cloud 30 N high pressure sunn 45 N60 N low pressure cloud polar latitudes high clear Global Satellite images often reveal clou patterns consistent with the above genera circulation Weather associated with the Pacific and Bermuda Highs Paci c high ves northward during summe mo r Produces strong subsidence inversion on eastern side During winter it moves south allowing polar Rent to bring precip to SW US Bermuda high transports warm moist subtropical air to US and southern nada This air can be unstable vveauiei 39 39 where you are located t new 1 I Fenland San Francisco 4 Lns Angeles y Pamli high Philadelphia t Allanla I l i Humid Bermuda mgr Weather associated with the Pacific and Bermuda Highsproof Los Angeles Anama Precipitation In on e m Precipitation cm A w r 7 o 0 JFMAMJJASOND JFMAMJJASOND Average Wind Flow and Pressure Patterns Aloft January 1 Vd H Average Wind Flow and Pressure Patterns Aloft July Walker Circulation The nonuniform distribution of land and sea and asymmetries in radiative conductive and latent heating that accompany it lead to Walker Circulations along the equator Jet Streams are also part of the general circulation Atmospheric jet streams are swiftly flowing air currents thousands of kilometers long a few hundred kilometers wide and a few kilometers thick Subtropical Jet situated above the subtropical highs at about 13 km AGL o en visible as a plume ofmoisture extending 39om the tropics to the subtropical regions Thejet streams exhibit a quotwavyquot pattesr lnargynd the globe Polar Jet autumn Palm 5 situated at about 10 km l GL over he polar ront Recall that tropopause height is proportional to t e mean ropospheric tempera ure Jet Stream Waves Often have troughs and ridges generally have a jet maximum jet streak 532 L in the base of the 39 trough transport heat pole ward cold air south and warm air north 331132 Q How are the polar and subtropical jets form a Position of the polarjet stream and the subtropical jet stream at the 300mb level on March 9 2005 Solid lines are lines of equal wind speed isotachs in knots Heavy lines show the position ofthejet stream core b Satellite image showing clouds and positions ofthe jet streams for the same day al a 2mm Thurman HigherEduneaun Jet Stream Formation Polar Jet Polar Jet boundary between warm air to the south and cold Isobaric aIr to the nort sw39face location of a large 39 7 139 gt i500 mb temperature gradient near 39 Xv the surface 500 mi Hence the lar e DC temperature gradient at the surface across the Polar polar front creates a large Cold air from Wmm a pressure gradient aloft a Side View 8 Jet Stream Formation Polar Jet recall that the strength of the geostrophic wind Is proportional to the magnitude of the pressure gradient force Hence the large pressure gradient aloft over the polar front generates a band of strong winds this is the jet stream Strong in winter weak in summer E 7 7 777 t 7 7 7 7 s 500 N S Warm g g Em E N alt 9 S W W by Map View cl 3D View Jet Stream Formation Subtropical Jet Subtropical Jet Forms on pole ward side of Hadley cell Hadley cell produce the subtropoical front Temperature contract 9 pressure gradiance created largely through conservation of angular momentum Other Jet Streams Lowlevel Jet over Central Plains of US Polar Stratospheric Night Jet Jet Stream and the Conservation of angular momentum Angular momentum is defined as the product of the mass m times the velocity v times the radial distance r Angular momentum mvr The Conservation of angular momentum The angular momentum of the rotating system does not change if there are no external twisting forces How ice skater change rotating speed AtmosphericOcean Interactions V ndwater interactions Surface water draf39t with wind Moving water piles up creating pressure difference The interaction can leads motion several hundred meter down into the wat Ocean currents Largely generated by wind gyres Account for about 40 of global heat transport Water moves at 2045 degree angle to wind dir due to coriolis force Move slower than winds several kmday kmhr Wind Ocean Current Red Warm currents Blue Cold currents Major Ocean CurrentS39 39 lt r l 39 i 39 i 4 quot lt 39 quot 1 i 7 1 B LE 10 1 Major Ocean Current I GulfSlrmm 939 South Equamrhl Current 17 Peru or Humboll Current 2 Nurllt Atlantic Drift IO Smith Ftlmmriai Limmmcunem ls Braii Curiem 3 Labrador Current 11 Equatorial Countercurrem 19 Falkland Current ALWM Grucltlmd min 12 Kurmhiu Curran 10 BcnguL LI Current 5 East Greenland Dri 13 North Paci c Drill Z Agulllas Current t LCdnJrv Cummi 14 mm Cunan 22xvmwi39ml Drift 7 North Equatorial Current 15 Oyashin Current strum Equatorial Culxntcluincm 1639Ili nnm Cuncm Ocean Front The boundary separating the two masses of water with contrasting temperatures and densities The Ekman Spiral Surface water Wind lt12 8 u D Average transport 1 Winds move the water and the Coriolis force deflects the water to the right Northern Hemisphere 2 Below the surface each successive layer of water moves more slowly and is deflected to the right ofthe layer above 3 The average transport of surface water in the Ekman layer is at right angles to the prevailing winds quot Upwe Ing summer l Wind aw may MW Emma Brings cold water from deeper regions to surface AZ 1 5 5 Northerly surface winds create V 39 quot 39 aquot offshore surface water ow w 339 CapeMemm Cold nutrientrich water rises to Samara replace the surface water good Lmngeags for shing Peru i g f Process is dominant when winds are parallel to coastline El Nino Spanish name for the male child Initially referred to a weak warm current appearing annually around Christmas time along the coast of Ecuador and Peru not good for their fishing industry and quano birds Can produce significant economic and atmospheric consequences worldwide Occur every 37 years lasting about one year Recent major events 19821983 and 19971998 The 9798 event was the strongest ever recorded El Nino Animation of warm pool El Nino refers to the eastward movement of warm water shaded red from the western equatorial pacific to the eastern equatorial pacific The animation of sea surface temperature SST anomalies to the right shows the unusual warming that occurred during m mums a the 9798 event 1 m Note that an anomaly is a departure from some quotnormalquot value An anomaly can be either positive warm or negative cold Trade Winds and Rainfall During A Normal Year the equatorial paci c into the western part of the paci c basin The sea level is actually higher in the western paci c Also note the upward motion and precipitation associated with the warm water and lower pressure in the we ern paci c Also note the cooler water high pressure and subsidence in the eastern aci ic The largescale zonal circulation in the equatorial plane is called the Walker Circulation During a normal year the easterly trade winds push and pile the water in a Nana Nmu cundiiiuns Trade Winds During an El Nino Year During an El Nino year the trade winds weaken This allows the water in the western pacific to move to the eastern pacific in the form of a quotkevin wavequot The equatorial counter current is also stron er Notice the change in the Walker Circulation and associated precipitation distribution Equaiov m El Nino Ccndiiions bquot6ug as H 39 Equalor 1 El Nl o Conditions NASAJPL El NinoLa Nina amp PDO httptopex www39plnasa govsciencee NOAASST animation httpwwwcd cnoaagovm apclimsstol rsstanimsh tml La Nina and the current state of the tropical pacific After the El Nino phase La Nina follows La Nina refers to the unusually cold water that is found in the eastern pacific ocean till lgt Hui u in La Nina canawnns Decembal i995 e 2am Thome Higher Educiuon 17 These three images depict the evolution of a warm water Kelvin wave moving eastward in the equatorial Pacific Ocean during March and April 1997 The white areas near the equator represent ocean levels about 20 cm 8 in higher than average while the red areas represent ocean levels about 10 cm 4 in higher than average El Ni o Southern Oscillation ENSO The Southern Oscillation The reversing surface air pressure at the opposite ends of the pacific ocean So are we currently in an El Nino La Nina or normal phase 97998 A 3 283 arm 1 1 86457 a 2 65 66 7239 vent 1 518 7677 EINi o In Al iii A i it will i a up L 9 1 went 8499 l 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 ENSO index La Ni o El Nmo 1 Dry and warmer weather in 1 Wet weather In CA and the CA and the southern part southern part of US of US 239 warmerthan normal 2 Colder than normal weather over a large part weather over a large part of North America of North America Polar lei Dry WE Minn Wam rphr v al El Nl u in La Nl a o my Thomson Higher Education Typical winter weather patterns across North America during an El Ni o warm event a and during a La Ni a cold event b Regions of climatic abnormalities associated with El Ni o Southern Oscillation conditions The Pacific Decadal Oscillation PDO Longterm Paci c Ocean temperature Fluctuation a Warm positive phase a Cool negative phase a 2mm mumquot HaherEducu Typical winter seasurface temperature departure from normal in C during the Paci c Decadal Oscillation s warm phase a and cool phase b The North Atlantic Oscillation NAO Refers to pressure variations associated with the Icelandic low and subtropical high pressure near the Azores 1 more and Stronger Storms 1 fewer and weaker storms crossing crossing the Atlantic on a more the Atlantic northerly track 2 eastern US experiences more cold 2 eastern US will experience mild air outbreaks and snowy Weather and wet winter conditions conditions 2O The Arctic Oscillation Slrongerwirids Weakerwinds a 394 Winter Winler la Positive warm phase in Negative cold phase a mm mm Higherzmm C ange in surface atmospheric pressure in polar regions and typical winter weather patterns associated with the a positive warm phase and the b negative cold phase of the Arctic Oscillation 21 ATSC 2000 Introduction to Meteorology Zhien Wang David Rahn Cory Demko Know Each Other Brendan Bryant Brian Hager Carl R Nowakowski Deborah Anne Graul Heath G Brown Jon Starr Marleigh Kay Coggin Matthew Scott Smith Amanda R Johnson Elizabeth R Barnes Leslie N Darnall Monica Rae Valdez Rachel L Reynolds Bartley James Brogan Brett Noel Worman Brian Thomas Desch Chad Eugene Plumb Christopher L Harnden Daniel G Barrone Danie Logsdon Brooke Ann Sweeney Jared Amrine Catherine L Brewer Jeremy C Kleinhans Chelsie R French Kyle Robert Langfoss Hauva Manookin Marc Andrew Hafner Jennifer M Varilek Michael Boniface Molony ll Summer D Johnson Mikel K HOOPGS Natalie Denise West Raymond M Gallegos Paige Michelle Vasko Scott Elton Headrick Sarah Georgia Grengg Amy M SUChOl Trulan Wright Eyre Why university science class A university education should help students develop their ability to think critically and objectively and provide educational experiences necessary to make informed decisions in the future as members of society A fundamental knowledge of some basic concepts in physical earth and biological sciences is necessary if we are to think clearly and make wise choices concerning such issues as land use food energy and mineral resources pollution and global climatic changes Why meteorology Why did you sign up Importance of Meteorology weather and climate Societ From drought and famine to devastating floods some of the grea est challenges we face come in the form of natural disasters created by weather Personal Dealing with weather and climate is an inevitable part of our lives Sometimes it is as small as deciding what to wear forthe day or how to plan a vacation But it can also have lifeshattering consequences especially for those who are victims of a hurricane or tornado gt d ln39 Challenges The dynamic nature of the atmosphere seems to demand our attention and understanding more these days than ever before greenhouse warming ozone depletion in the stratosphere hurricanes A satellite movie ofHun39icane Katrina About this course The course is intended to aid your own personal understanding and appreciation of our earth s dynamic atmosphere Class Syllabus The importance of Atmosphere Our atmosphere is a delicate lifegiving blanket of air that surrounds the fragile earth How long can we survive without the following Food Water Air What will happen if the earth without a atmosphere Overview of the Earth s Atmosphere The hot Sun is the center our solar system Where we live The earth is at an average distance from the sun of nearly 150 million kilometer km or 93 million miles mi Energy from the sun drive everything on the earth Mercury Eartl L Hg 6 Velus ers k l Jupiter Saturn Uranus Neptune 2am Thnmsun HigherEuucatinn Fig 11 p 2 What exist in the atmosphere The earth s atmosphere is a thin gaseous envelope comprised mostly of nitrogen and oxygen with small amounts of other gases such as water vapor and carbon dioxide aerosol and clouds Satellite image of the Earth and its Atmosphere A Breath of Fresh Air Figure 1 An atom has neutrons and The volume of an average size breath of air is about a liter Near sea level there are roughly ten thousand million million million 10 air molecules in a liter and molecular oxygen 02 A breath of air1022 molecules Electron Proton In the entire atmosphere there are nearly 1044 molecules Neutron protons at its center or nucleus Molecules are combinations of two or more atoms The air we breathe is mainly molecular nitrogen N2 Composition of the Atmosphere Near the Earth s Surface Variable Gases Nitrogen Water vapor Oxygen Carbon dioxide Argo et ane Heiu Nitrous oxide Hydrogen zone eno Particles 7 Chlorofuorocarbons lABLE Ll Composition of the Atmosphere Near the Earth s Surface nmmiimr GASES wantmu GASES man irwuinuw V Ni m iymiwi m HM remit Swulml Numgm N mm m er mm 10 Oxygen 01 2095 Carbun dioxide coz 003 Algun Ar W13 Moilmnc Lu n0mii7 Neon Ne mm x Nitrous uxidc N10 000003 Helium He 0 non Glam 0 MIHUUIH Hydrogen Ir mmnim Particles dust sonl etc i 0000001 X9110 Xe nmmmw ClllulU ul ULnl39bmtgt ores Lurinnnnu lsrmuspherlc vzluzsumliitudes between in kin and so km nreuhmu 5 m i ppm m 339 Wm mm mm LU 0 0002 Table 11 p 3 Water Vapor The most important variable gas the amount vary a lot In warm steamy tropical locations up to 4 ln colder arctic areas a mere fraction of a percent Examples showing the existence of water vapor Why water vapor change so much Water Vapor Water vapor is invisible but become visible after forming clouds liquid or solid water 2 A natural component of the atmosphere Low concentration 37 semossip 00 An im portant greenhouse as Sources Sinks a ZDEI ITnumsan nghzr Edumtmn Longterm observations indicate that CO2 concentration is increasing Why 002 concentration is increasing Good or bad CO concamrauon ppm E u 586052346653107274767380n8436339092549695000204a Van Ozone a low concentration variable gas Good and bad aspects of ozone Ozone hole over Antarctic Ozone Dabson Umts l ig 16 p 7 Mercuyy Earth trgt Venus Mats smum Uranus Nepmne ABLE 1 rmngnm Data on39Planets and the un AVERAGE msmm mam SUN AVERAGE SURFALE MAIN ATMOSPHERIC DIAMETER TEMPLRM URE Numemv MHUN S r F Kilomalm quot V Sun L391 X IH S MID ULSUU Men qu 4850 58 260 500 VL IIH Ill 2 1le 461 mm CL Earth 12742 150 IS 9 N1 0 Minx 6800 28 00 75 C0 TllpilEl 143000 778 i110 UNIIa Sutuln JJIJYHU L427 190 H I39 a Umnm 51800 2869 ZIS H CHl Ncplune mm 44 215 NNCH Plum 3mm 5mm 235 391 CH4 Sunlil side The Early atmosphere The earth s first atmosphere 46 billion year ago likely hydrogen and helium as well as hydrogen compounds such as methane and ammonia Other gases increase as gases outpoured from the hot interior Known as outgassing What come out of erupting volcanoes Water vapor 80 CO2 10 N2 a few percent The second atmosphere Erupting Volcanoes Evolving the current atmosphere 78 N2 and 21 02 High N2 High 02 More water Vapor High energy rays break water vapor Clouds and precipitation CO2 decrease H20 9 H2 02 Air is rich in N2 Important variables 1 Weight Weight mass x gravity An object s mass is the quantity of matter in the object 9 not change Gravity change by many factors Locations on the earth Change with altitude on the Earth Change with the mass of the other object moon sun and earth The weight of the atmosphere near seal level is 12 kg m3 2 Density The density of air or any substance is determined by the masses of atoms and molecules and the amoun of space between them mass Mass density volume Mass density ofthe atmosphere nears sea level Or measured with number of molecules rather than the Number of Molecules Number density Number density ofthe atmosphere nears sea level 3 Temperature The temperature of air or any substance is a measure of its average kinetic energy Simply stated Temperature is a measure of the average speed of the atoms and molecules where higher temperatures correspond to faster average speeds Tem peratu re Scales Kelvin scale absolute zero Fahrenheit scale F Celsius scale C c 59 F 32 K c 27315 4 Pressure force area Applications of using the pressure definition pressure How to increase pressure Increase force or Decrease area How to decrease pressure Increase area or Decrease force Air Pressure Demo Observe what happen when we pump air out of tube Wate r force pressure area Air molecules are in constant motion On a mild spring day near surface an air molecule will collide about 10 billion times each second with other air molecules Each time an air molecule bounces against a person or other surfaces it gives r h r a mypus me The standard values of UHitS 0f Air Pressure atmosphere at the seal level IllIbar m 101325 mb Hectopascal hpa 101325 hpa Inches of Mercury H9 2992 in H w y u um pressing against each square inch ofyou with a force of 1 kilogram per square centimeter 147 ounds per square inch The force on 1000 square centimeters a little larger than a square foot is about aton Laramie 780 mb or 1132 pounds per square inch Physical Behavior of the Atmosphere The following generalizations describe important relationships between temperature pressure density and volume that relate to the Earth39s atmosphere 1 When temperature is held constant the density of a gas is proportional to pressure and volume is inversely proportional to pressure 2 If volume is kept constant the pressure of a unit mass of gas is proportional to temperature 3 Holding pressure constant causes the temperature of a gas to be proportional to volume and inversely proportional to density The Gas Laws These relationships can also be described mathematically by the Ideal Gas Law Two equations that are commonly used to describe this law are Pressure x Volume Constant x Temperature and Pressure Density x Constant x Temperature Em bottle Baumquot my Demo to verify the relationship 3 Holding pressure constant H at Water Air pressure and density decrease with height Air molecules Do you have any E Mammy experience to g 3 show these 5 trends Low High increasing gt 30 50 4o 20 so A E E 3 lt1 9 E E a 20 E lt 10 r r r V r lt l commercia l Hmmit of Mt Everest aircraftflight g x I o m 3oo mb altitude I bove 200 mb L mie 0 I l39 l I l o 100 500 700 900 moo Pressure mb Layer of the atmosphere 1quot 7 How Temperature W Milff m 7 changes with height wa quot 5 M This is the average temperature profile U lmh 4 According to the temperature structure the quotquotquot quotWW quot w as 5 atmosphere can be divided quot 39 into the following layers 307mm mmwm quotmm Exosphere W quotquot 39 TYWWUJU mowquot m Thermosphere m f Mesosphere I WM mm gt100 gt30 EU 40 gt20 0 20 15 EU 0 Stratosphere 420 um JID J 0 no 120 F Troposphere 1m Troposphere On average 0 1 1 km 0 MEWS HERE m Contains all of the weather 0 I WWW ls kept well stirred by rising and 907 descending air currents soquotquotquotmMes quota se 77777 5U Average lapse rate at which the Mm 39 air temperature decrease with A m 7 7 39 7 mm HERE Mb 4 height is 65 Ckm or 36 F 0 A 1000ft lt 507 s lms W730 Temperature inversion can occur 40 39 in this ayer a The heIght of tropopause varIes 323mm with latitude and season Wme mm m Higher over equatorial regions 10 TL Tquot TP OHER E 39 and lower in polar regions aquot i i iquot i J l WOW Higherin summer and lower in 73900 75 75 7 72 0 20 40 m C 47D 730 740 o M ED 12E F WInter Fig 110 p 11 123 Stratosphere A M m THERMOSFHEHE Temperature increase with J i 00m mn7 60 height but Is stIll extreme cold 917 7 A7 7 7 7 7 7 7 Mesopausa r H 7 7 r 7 7 7 7 r r 7 7 7 SC 7 m 5U The InversIon suppress the m 0 r vertical motion stratosphere is a 7 7 39 MESOSPHERE Ulrnb 10 stratIerd layer 5 Svravcpaus 7 7 v 7 Vmb HIgh ozone concentratIon play lt a major part in heating air in this STRATCSPHEHE mm in layer Ozone mum m The maximum ozone is around 25 km p l DPOSPHERE l i l l 39i39 I l I 7100 750 7639 740 725 0 20 AD 60 C The ozone layer absorb most 7 20 fat at u no so v20 Temperature solar UV radIatIon Fig110 p11 18 Exosphere Light molecule such as H2 can escape the earth s gravitational pull Thermosphere Temperature increase with height Oxygen molecules 02 absorb energetic solar rays warming the air Soar activities highly impact temperature here 0 gt L 7500 0 500 1000 600 Mesosphere middle sphere Temperaluie l Cl Air is very thin here Temperature decrease with ere Temperature Variatio with latitude and season rate MM 5 AnnyalMean Trupopause helghl insum 5 i g m E 5 5 ran 740 gt 0 0 40 A60 50 40 30 D ID TamvlmmaK39Cl Tempsmlure c1 anUWSIJ Lapse Fate FelatiVe39Y conStant Def tem peratu re Inversion region of negative lapse Almude km Layer in terms of electrical properties lonosphere An electrical eld region Within the upper atmosphere Where fairly large concentration of ions and free electrons exist Ions 7 atoms and molecules that lost or gained one or more electrons Layers according to com position 300 Ho m osph ere A Nitrogen and oxygen are well 206 mixed 78 and 41 Heterosphere r on Heavier atoms and molecules such as oxygen and nitrogen tend to settle to the bottom of the layer 006 mm 7 0 While light gases such as hydrogen and helium oat to the Tempeialure re top The ionosphere is very important for radio communication Stroneg impacted by the solar activity Night Temperature Measurement techniques 73 Hanna nmnl n mm limnnln n Maw 1 m ummmbmme mun Weather and Climate Weather the conditions of atmosphere at any particular time andplace Climate represents the accumulation of daily and seasonal weather events over a long period time mean and extremes Weather Elements 1 Air temperature the degree of hotness of the air 2 Airpressure the force of the air above an area 3 Humidity a measure of the amount of water vapor in the air 4 Clouds a visible mass of tiny water droplets andor ice crystals that are above the earth s surface 5 Precipitation any form of water either liquid or solid rain or snow that falls from clouds researches the groun 6 Visibility the greatest distance one can see 7 Wind the horizontal movement of air QUESTION FOR THOUGHT Which ofthe following statements relate more to weather and which relate more to climate a the summers here are warm and humid b cumulus clouds presently cover the entire sky 0 our lowest temperature last winter was 29 C d the air temperature outside is 22 C e December is our foggiest month f the highest temperature ever recorded in Phoenixville PA was 44 C on July 10 1936 g snow isfallmg at the rate of 5 cm per hour h the average temperature for the month Of January in Chicago IL is 3 C Meteorology a brief History Meteorology the study of the atmosphere and it s phenomena First discussed by Aristotle 340 BC wrote a book entitled Meteorologica summarized meteorological knowledge to date 17th18th centuries meteorology came into being with the advent of met instrumentation SUCh as thermometers and barometers 19th century met observations were being made routinely transmitted with the telegraph 22 Meteorology a brief History 192039s Concept of airmasses and fronts was formulated in by Norwegian meteorologists They developed a theory for the evolution of mid latitude cyclones still used todayll After WWII meteorological radars were implemented 195039s computers ran first models ofthe atmosphere 196039s first meteorological satellites were launched Tiros I 199039s National Weather Service was modernized We are now able to observe meteorological phenomena on most a spatial scales Satellite View of Weather Weather Map Wind the horizontal movement of air LOW and high Winds to blow clockwise and outward from the center of high and count clockwise and inward toward the center of low pressure centers Air rise in low form clouds Air sink in high clear sky for most of time Fronts across which there is a sharp change in temperature humidity and wind direction Coldfront Warmfront Station from Occludedfront a 2mm Thurman HmherE ucaimn Fig 115 p 21 24 Weather Symbols and the Station Model Appendix B I Manny39an m m 5mm Mum e m l a D o I 6 a 2mm Tropical Weather Tropics region between 235 N and S ofthe equator Amount of solar radiation does not vary much from season to season but is relatively intense winds are generally NE E or SE easterly trades tend to be quite weak as well wh wind flow is best visualized with streamlines instead of sealevel pressure Types of weather systems found in tropics thunderstorms tropical squall linesclusters nonsquall clusters tropical depressionsstorms and hurricanes Easterly Waves Tropical weather is often initiated by easterly waves gt Easterly waves have wavelengths of about 500 km position is found in atrough of at streamline pattern convergenceupward motion on east si e 7 divergencydownward motion on west side A travel from east to west at 10 quot 39 20 knots N Hurricanes are often initiated by easterly waves Lamude N Anatomy of a hurricane Cloud shield 500600 km in diameter Eye 2050 km in diameter relatively warm light winds clearbroken clouds low surface pressure Eyewall very strong winds ring of intense thunderstormsrain surrounding the eye Vertical cross section of the hurricane circulation At lowlevels air flows cyclonically into the center of the storm Diverging anticyclonic motion at tropopause level Rising motion occurs in the eyewall thunderstorms adjacent to the eye Subsidence on outer edge of storm Rain bands Sinking motion in the eye The cloud mass is Hurricane Katrina s eye wall and the clear area is Katrina s eye photographed inside the eye on August 28 2005 from a NOAA hurricane hunter aircraft sloping eyewaii A three dimensional satellite view of Hurricane Katrina passing over the central Gulf of Mexico on August 28 2005 The cutaway view shows concentric bands of heavy rain red areas inside the clouds encircling the eye Notice that the heaviest rain largest red area occurs in the eye wall The isolated ta cloud tower in red in the northern section of the eye wall indicates a cloud top of 16 km 52000 it above the indicate that the storm is intensifying Arrows show surface winds spinning counterclockwise around Hurricane Dora situated over the eastern tropical Pacific during August 1999 Colors indicate surface wind speeds Notice that winds of 80 knots 92 mihr are encircling the eye the dark dot in the center Wind speed and direction obtained from QuikSCAT satellite NASAJPL Latitude N ms 118 117 116 115 Longllude w 40 Wind speed knots Ingredients for hurricane formation Warm seasurface temps greater than 26 C 79 F Deep moisture at low levels Light winds throughout troposphere Need convergence a trigger weak frontal boundary ITCZ easterly wave Typically form between 5 20 latitude not on equator Factors inhibiting hurricane formation Cooler SST39s drier air at low levels Strong trade wind inversion subsidence created by subtropical highs Strong upperlevel winds Hurricanes form over warm tropical waters This image shows where sea surface temperatures in the tropical Atlantic exceed 28 C 82 F warm enough for tropical storm development during May 2002 The energy for hurricane comes from the direct transfer of sensible heat from the warm water into the atmosphere and from the transfer of latent heat from the ocean surface Organized convection theory for hurricane formation lnitially need an unstable environment cold air aloft warm air at the su ace Have vigorous growth of thunderstorms lntense latent heating heats the column of air near the center of the storm generates high pressure divergence aloft also lowers the pressure at the surface lower surface pressure increases the pressure gradient at low levels generates stronger surface winds Stronger winds increases friction via choppy seas Stronger convergence into storms center Enhance convection back to l The above is a positive feedback loop enhancing the storm39s strength N 5 39NOF Surface air pressure Increasing Surface wind speed increasing 9 2m Thurman Higher mum Tropical disturbance weak low pressure winds increase to at least 20 knots Tropical depression sustained wind speeds increase to at least 35 knots mo 90 0 M 7 no Lengiiutis Hurricane Movement 1139 L39Vcinne u an an Some erratic paths taken by hurricanes 39 The paths of eight am hurricanes that impacted Mm De m Florida during 2004 and mm 1 9752 in Edam 2005 1 Ophelia Frances 90504 39 Dennis Katrina Wilma 71005 82505 anne 1024 05 1 Charley 82905 92504 Iva 81304 91504 mum Thomson HigherEducaimn Hurricane Destruction Destruction by hurricanes is created by Winds often the winds surrounding a hurricane are stronger on one side than the other why The storm surge high winds generate large waves up to 50 feet highii combined with lower pressure over the ocean surface the high winds create an abnormal rise in sea level the higher sea level creates a surge of water onshore producing coastal flooding most hurricane fatalites are related to the storm surge Hurricaneproduced tornadoes a 2mm Thomsun Hmher Educnoun Beach homes along the Gulf coast at Orange Beach Alabama a before and b after Hurricane Ivan made landfall during September 2004 Red arrows are for reference A hurricane moving northward will have higher sustained winds on its eastern side than on its western side gt When a storm surge moves in at high tide it can inundate and destroy a wide swath of coastal lowlands Willie SaffirSimpson Hurricane Damage Potential Scale Saf rSimpsanllurricane DamagePotential Scale 5cm NUMBER ATEGDRV mum PRESSURE mu in 293039 963979 91 Hm 920 944 lt Jlll zlzwl 18504831 2737 lrl iul7 171 72 Rl lt17I7 wmns mm sum mihr Aunts n 11 71795 M732 vla 15 96 1 Ill 33 95 64 111420 91 ll3 V Il lllrlSS 1147135 13 18 wan 55 gt133 gt135 gtIb gt35 111mm llnumg Iminly m m rubbery uul unnuchnml quotwhile humus Sumo trees blown dawn muior dam age 0 2mm mobile Iwma damage 11 mars of buildings romgc Imum ed 1mm tram Lirgc lt 11ml sunw slnlduml 111qu in small 1mm lug All signs blown down extensive dam age In r11ufsvindm39s1md dams to w km a mi 1 major damage 0 lower Hours of slruclures near shore some 111mm in windows 1 ml tours ings um im damage 1 lmvc lluun 1111 me Ill 3 m h m alvuvu MN 1 9112111111111quot 501 I ul39xlmrc The number of hurricanes by each category that made landfall along the coastline of the United States from 1900 through 1999 All of the hurricanes struck the Gulf or Atlantic coasts Categories 3 4 and 5 are considered major hurricanes 60 m 50 m c m g g 40 f 6 g 30 60 g 49 20 41 10 14 3 O 1 2 3 4 5 Calegory RANK Hu micmi 1 Florida Keys 2 gaming 3 And rcw t Kan ina 5 Florida KeysVSrmlh Texas 6 i Ioiigia magnesium 7 Donna 8 Tgicias Gnlvumn 9 Louisiana Grand Isle 10 mm arms I l Curl1 12 Hugh l3 Florida Miami BZUD IThummn HIgherEduzimn CE MlLLlEARSINCNES 8922635 zoi7i7 9372737 3292253 9302146 9312149 93 274 93112249 93 III49 9342758 mason 5 5 5 MAIN mill A community in Homestead Florida devastated by Hurricane Andrew on August 24 1992 Color radar image of Hurricane Andrew as it moves on shore over south Florida on the morning of August 24 1992 High winds and huge waves crash against a boat washed onto Highway 90 in Gulfport Mississippi as Hurricane Katrina makes landfall on the morning of August 29 Flood waters inundate New Orleans Louisiana during August 2005 after the winds and storm surge from Hurricane Katrina caused several levee breaks Hurricane Watches and Warnings Hurricanes are monitored with Satellites radars ships aircraft and buoys Ever wonder what it is like to fly through a hurricane 9 NOAA P3 aircraft penetration Hurricane watches are posted when the hurricane poses a direct threat to an area Hurricane warnings are issued when the storm appears like it will hit an area within the next 24 hours How are hurricanes named When a tropical depression reaches tropical storm strength it is given a name Alphabetical order Alternate between malefemale names A complete list of names can be found at the National Hurricane Center web site httpwwwnhcnoaagovaboutnameshtml 9 my mama Higher Baum 5110 i D Er jck Fln sie cu Henriette I vo Iuliettc Kiko Xaviu ulanda Why are cold fronts usually associated with showery weathers How ca warm fronts cause freezing rain and sleet to form over a vast area during the winter And how can one read the story of an approaching warm front by observing its clouds mum Thnmwn Higherducanun Air Masses Definition Large body of air with similar temperature and moisture characteristics in any horizontal direction at any given altitude Cover many 100039s of square kilometers Part of weather forecasting is determining air mass characteristics how they may be modi ed and their movement Regions Source regions light Win 5 So where are the good source regions Arctic Tropics Air masses tend to clash and interact in the middle latitudes at uniform composition d Air mass source regions and their path Air Mass Source Regions Regions where air mass originate are know as Source S becomes c TABl E 111 Air 39 C SDUREE REGION llnk conlinenml c ater maritime m Extremely cold cP air is sometimes denoted a Extremely hot humid mT air is sometime denoted by mE Air Masses on the move Edan air mass is colder than the surface over which it is moving POLAR r P Cold my stable n11quot Cool moisl unstable Air Mass Classification Four general categories according to source region see table tcA if an air mass is warmer than the surface over which it is moving quotwquot is added Example a cP air mass moving over the great lakes in December Pk Jassi ca bh and Characteristics TROPICAL r c Hot dry stable r aloft unstable surface air In Warm moist usually un stable Air Masses of North America 1 Continental PolarArctic 2 Maritime Polar air cPIcA airmass mass 3 Maritime Tropical 4 Continental mTair mass Tropical cT air mass Continental PolarArctic cPcA air mass Stable cold dry air masses originating over N Canada and Alaska Eventually plunge southward to interior of US as a Shallow dome of high pressure why Can reach Gulf of Mexico and Florida freeze crops Usually do not move west of Rocky mountains mountains confine cold airto the east Upslope precipitation is common east ofthe rockies as the 0P air mass slides to the south mmms m 25 k 29 ill 7 lavu 23 JG 1 as s H 122352 M m 9 Averagexurppweitlevel wind flow heavy arrows and surface position of anticyclones H associated with two extremely cold outbreaks of arctic air during December Numbers on the map represent minimum temperatures F measured during each cold snap bring relief to hot humid reglo s During the summer cP air mass can n Typical vertical temperature profile over land for a summer and a winter cP air mass 2 av Winter Summm l 40 o in a GE 4 12 lumumaluio Produce lake effect snows as they move over the great lakes Warm water mum quotmmsnn Hmer Enucl un unvmrwm Areas shaded purple show regions that experience heavy lakeeffect snows When an air mass moves over a large body of water its original properties may change considerably mP Air Mass West Coast Originate over Asia Tends to be unstable Heavy rains as cool moist air flows over mountains along west coast mP is modified how7 by time it reaches interior of US though is milder than cP After crossing several mountain ranges cool moist mP air from off the Pacific Ocean descends the eastern side of the Rockies as modified relatively dry Pacific air mP cool air gt moist Pacific Olympic Cascade Rocky WEST Ocean Mountains Mountains Mountains EAST c znn Thummn Higher Emlth East Coast not as common as west coast mP colder than west coast mP usually brought onshore by high pressure to the north of US andor low pressure to the south moving up the coast Light snow m Freezing rain Light drizzle 7A7 Stationary front mT Air Mass largely originates in Gulf of Mexico western Atlantic affecting eastern 23 of countr also originates in tropical eastern pacific SW monsoons in ummer warm moist unstable confined to southern US in winter important source of moisture feeding stor A constant supply of mT air from the Golf of Mexico can bring recordbreaking maximum temperatures to the eastern half of the country x Minimum lem lings PF Malmum iemperaimes quotFl Weather cormio39ri39s during an unseasonably hot spell in the eastern portion of H quot quot ule 15th and 20th Oprl39il 1976 cT Air Mass originates over Mexican Plateau region and desert SW hot dry unstable at low levels stable at upper levels boundary between cT and mT is often called the dryline The dryline is o en seen in surface and satellite data and is a favored location for storm initiation Atmospheric Fronts Introduction Front boundary transition zone between two different air masses The two air masses have different densities Frequently they are characterized by different temperatures and moisture contents Front has horizontal and vertical extent Frontal boundaryzone can be 1100 km wide The upward extension ofa front is referred to as a frontal surface or a frontal zone 1024 1020 Types of synopticscale fronts stationary fronts cold fronts warm fronts occluded fronts lDZE W2 me 24 024 02 l0l2 SlMPLlFlED KEY quot1P WW Gold from A39A Siatlonafy from m Occluded rm 5 ngl ll SHOW n Liglitvam A Steel Wind direction Ni Wl d speea no kncls 22 Air lemueralule 22W me 15 Dew DOW l5F Stationary Fronts Has littleno movement Denoted by alternating coldwarm frontal symbols Semicircles face toward cold air Triangles point toward warmer air Associated weather clear partly cloudy cloudy light precip usually nothing severe If the stationary front starts moving north in the example to the right it will become a warm fronts If the stationary front starts moving south in the example to the right it will become a cold fronts Stationary rmm Cold Fronts Zoneboundary between warmer more moist unstable air Eusually mg being replaced by colder drier more stable air c Location of cold front leading edge of sharp temperature change moisture content dew point ges dramatically wind shift direction and speed v quot Pressure and pressure change V pressure tendency is useful i Since the cold front is a trough of low pressure sharp changes V39 in pressure can be significant in locating the fronts position Figure 1113 Location of cold front often cloud showersthunderstormssometis severe A squall line A Doppler radar image showing precipitation patterns along a cold front similar to the cold front in Fig 1113 Green represents lighttomoderate precipitation yellow represents heavier 39 39 39 and red the most likely areas for A vertical view of the weather across the cold frontin Fig 1113 along the line X X Altitude km Warm air ahead of front is lifted up and over Can get intense showersthunderstorms at frontal boundary Cs and Ci clouds are blown ahead of the front by upper level winds Cloud base is generally lower behind the front Further behind the front the air is quite dry few clouds Steep frontal boundary 1 50 slopes backward into the cold air Frontal speed averages 1525 knots Temperature and wind profiles on either side of cold front 0 FJ 39gtF Frontolysis a condition cause a front weaken and dissipate the temperature contrast across a front lessens Frontogenesis a condition cause a front to strengthen and regenerate into a more vigorous frontal system the temperature contrast across a front increases WARM AIR WARM WATER a 2mm mum aquarium The infrared satellite image a shows a weakening cold front over land on Tuesday morning November 21 intensifying into b a vigorous front over warm Gulf Stream water on Wednesday morning November 22 weather is partly cloudy and warm Cool mP air 5 0 as 7 m 4 s 70 470 na 07 2 A back doorquot cold front moving into New England during the spring Notice that behind the front the weather is cold and damp with drizzle while to the south ahead of the front the lABLE 112 Typical Weather Conditions Associated with a Cold Front in the Northern Hemisphere WEMMR ELEMENT EEFURE PASSING WHILE FASSlNG AFTER PASSING Winds Smith or sullthwcu cinn mining Wm in nm lhwesl Temperature Warm sininnn Imp Smarty dropping Pressure aning simulin Minimum men slurp risc Rising slmdily Clouds increasing Ci Cs lien Tcu nr CL O cn Cu so when gmund is wami either Tau nr Cb l rvcipilnliun Slmrl periml hl39ahmvcrx hmvcn ni Min nnmm mnminm quotCL ig inlansil ul39ihmvcrx Ilmnnlur nnd llglimiug mm cl ring Visibiliiy FJir to pour in luu Pour ruian byimpnwiug Goad except in showers Duw puim inn ielndins may Slurp inn Lnneiinn e 2107 Thurman HmherE ucahan In fact no two fronts are exactly alike Warm Fronts Zoneboundary between advancing warmer more moist air usually mT and cooler drier air usually mP Average speed is about 10 knots Often associated with quotoverrunningquot Frontal passage Clouds associated with warm fronts frontal surface has a much smaller slope 1300 than for cold fronts Often produces widespread nimbostratus precip near front Warm frontL 600 km Temperature and wind profiles on either side of warm front Frontal inversion ln 39 p Ligmmmudemle min snuw 51w Drizzle m none ordrizzlc showers in mnmwr 39Fdo x bi39 Dew puinl Steady rise Sieady Rise Ihen steady H mm Thnmsun Higher Educahun Drylines represents a narrow boundary where is a steep horizontal change in moisture A dryline moves across Texas and 99 Oklahoma during the y late afternoon in May vr inquot quotw mm Radar fine lines r l eastern dryline Tl FIG 2 WSR BBD 05 deg reflectivity dBZ at Amarillo TX valid a 2308 UTC 22 May 2002 and b 0007 UTC 23 May 2002 Reflectivity scale provided to the left The locations of the eastern and western dryline are shown in a Dryline and convective initialization Occluded Fronts Occlusion 0 Why do they form Cold front moves l fast catches up the warm front v 0 There are two types of occluded fronts 39 cold occlusion warm occlusion Cold Occlusion Cold front quotliftsquot the warm front up and over the very cold air Associated weather is similar to a warmfronr as the occluded front approaches Once thefronthaspassed the associated weather is similar to a cold from Most common type of occluded front Vertical structure is often difficult to observe I rg l m Cold occluded lmnl Warm Occlusion cold air behind cold front is not dense enough to lift cold airm ahead of warm front cold front rides up and over the warm front upperlevel cold front reached station before surface warm occlusion JTABLE 114 1 Ea39ltWea WEATHER HEM EN l BEFORE PASSING Winds Earl suudieaxl or south Temperature Cold type Cold or cool Warn type Cold l rmurc Usually falling Clouds in Lhisurder Ci Q As Ns Prctipilnlinn Light moderate hemquot preripiuliun Visibility Pour in precipitation Dew puiiu 51 de mom momma ngnuzaumun aniiv lnlifdai zdiimn n rinh Mimi WHILE PASSING lxriulzle Dropping Rising Luw puinl N5 sometimes Tcu and Ch Light moderate or heavy continuous predpilnliml ur showers Poor in precipitation Usually slight drop cspcciillly if L39OidrllCL iIIdELi AFTER PASSING We in nurlliu39esl Colder Milder Usually rising Ns As or scattered Cu Liglii loirimlcrale pmipilnliun followed by general clearing Improving Slight d mp although my riw iril il l39ll39lllrll k39illli d Visible satellite image showing a midlatitude cyclonic storm with its weather fronts over the Atlantic Ocean during March 2005 J 730 740 750 Tropupausa 60 Slralosphere Jel 10 COIE 39 4O 5 730 3 E Tropopausr V 40 5 30 Upperrronl 710 720 Troposphare o quot0 Surllacc mu m 0 Y P H North 200 km South An idea IEN eM vertical view of an upperair front showing tropopause heavy red line isotherms in C dashed gray lines and vertical air motions The polarjet stream core maximum winds is flowing into the page from west to east a 2m Formation of Dew and Frost Dew forms when the temperature cools to the dewpoint temperature Dewfrost often form only close to the ground eg not on a bush Dew and frost most often form on clear calm nights why Dew can be an important source of moisture during periods of low rain fall If T Td lt 32 F get frost Dew point is called the froslpoinl Freeze andBlaekfrost In very dry weather the air temperature may become quite cold and drop below freezing without ever om reaching the frost no Visible frost forms a cold winter morning Condensation Nuclei Keyfor the Formation ofHuze Fog and Clouds The process of condensation of vapor gt water to form a cloud drop is not that simple in the atmosphere NEED Condensation Nuclei to form cloud drops Condensation Nuclei small particles in air created fromby dust sulfate particles from phytoplankton in ocean They are most abundant in lower troposphere over urban areas They are quite small relative to a rain drop or cloud drop Sizes and Amounts of CCN Note 1 cm3 is about the size of your thumb Total mass of CCN put into atmosphere each year is about 2x1012 kg TABLE 51 Characteristic Sizes and Concentration of Condensation Nuclei and Cloud Droplets APPROXIMATE NO OF PARTICLES TYPE OF RADIUS PER CM PARTICLE MICROMETERS Range Typical Small Aiikcnl cnndenv lt03 1 in 1000 sntion nuclei 10000 Large condensation nuclei 02 to 10 1 to 1000 100 Giant cniidcnsalion nuclei gt 10 lt lo 10 Fog and cloud droplets gt10 10 to 300 1000 Two types of CCN Hydroscopic water seeking H20 readily condenses on these ocean salt is a good example sticky salt shaker when humid Hydrophobic water repellant H20 does not readily condense on these wax on car Hygroscopic nUClei Hydrophobic nuclei Formation of Haze Two types dry haze largegiant particles in the air smoke smog dust wet haze HZO condenses onto hydroscopic CCN can occur at RH39s as low as 75 wet haze has a dull gray white color Fog introduction Forms as the RH increases to 100 haze particles grow into fog cloud particles near the ground Fog is really a cloud near the ground International de nition Visibility is less than km NWS de nition Visibility is less than or equal to 6 miles and TTd lt 5 F Fog in polluted areas can be a health problem since it becomes acidic Formation of Fog Fog forms in one of two general ways Air is cooled below its saturation point By evaporation and mixing A fog droplet with a diameter of 25 um settles toward the ground at about 5 cms 2 ins Fog is maintained by new fog droplets Types of Fog Radiation Fog Advection Fog Upslope Fog Steam Fog Let39s look at how each of these are formed F ormation of Radiation Fog Radiational Cooling Need shallow moist air near surface clearcalm nights although light winds will bring more air in contact with ground Radiational cooling allows the temperature to drop to the dew point Also called ground fog Formation of Radiation Fog T Td Once the temperature reaches the dew point radiation fog begins to develop Common in the fall especially when our weather is dominated by high pressure often forms in valleys first since this is where the coldest air is called valley fog Q Do radiation fogs develop upward or downward Q When is radiation fog the thickest Rmmmn Fug Radnmmi hug night time LW I lllghl llme LW I radiation I Inversion Y I Q waim moislaiil fog mm montaul nme mid ground heat transfer heat transfer by conduction bv conduction Visible satellite image of dense radiation fog in the southern half of California s Central Valley on the morning of November 20 2002 The white region to the east right ofthe fog is the snowcapped Sierra Nevada range During the late fall and winter the fog nestled between two mountain ranges can last for many days without dissipating The fog on this day was responsible for several auto accidents including a 14car pileup Formation of Advection Fog 0 Common off the west coast of the US Coldt current along coastline and warm water further to the wes westerlies moving in from the warmer water to the colder water westerlies advect warm moist air over colder water 0 Heat is transferred from the warm moist air to the cold water near the coast via conduction The parcel reaches saturation forms fog and is advected onshore NEED a light breeze for this process to occur Ewe westerlies T260 TWC gt Td T70quotC westerlies TWO gt Here advection fog having formed over the cold coastal water of the Pacific Ocean is rolling inland past the Golden Gate Bridge in San Francisco As fog moves inland the air warms and the fog lifts above the surface Eventually the air becomes warm enough to totally evaporate the fog Advection fog can be an important source of moisture for plant life along the CA coast it rarely rains there during the summer months Other favorite places to observe advection fog Where two ocean currents with different temperatures ow next to one another Warm moist air from the gulf of Mexico moves northward over colder land lce fog in arctic Along an irregular coastline advection fog is more likely to form at the headland where moist surface air converges and rises than at the beach where air diverges and sinks Headland Fa Upslope Fog Take a parcel over the Gulf of Mexico and move it towards Denver As the parcel ascends up the slope it expands and cools to the dew point Upslope fogclouds then form Need winds to move air up the slope Need a slope Steam Fog Seen over lakes or heated pools in winter Form it when cold air over a warm water lakes the cooler drier air and the transfer occurs in a shallow layer near the lakes surface Hence you have an unstable situation with warm saturated air at the lake39s surface below cooler air the air rises forming steam fo Al 1 later time m steam fog ill a Cold Heat and moisture are transferred from the warm water to Even in summer warm air rising above thermal pools in Yellowstone National Park condenses into a type of steam fog PARCEL a Tz C Ws55gk9 wsom I Other foggy locations Distribution of Foggy Weather around the US Where is it foggy Paci c Coast Appalachian highland region New England Foggiest spot in the US Cape Disappointment WA it39s foggy for 2556 hours per year or about 107 days Mistake Island off coast of Maine 1580 hours per yeai t Washingtonl experieni 7 quot fog on about 300 days each Fog can be a signi cant forecast probem aviation ground transportation maritime activities Introduction to cloud types Introduced in 1803 by Luke Howard an English naturalist modified by Abercromby and Hildebrandsson in 1887 Clouds are comprised of liquid droplets of various sizes andor ice crystals They are characterized according to their height location in the atmosphere and their vertical development TABLE 52 The Four Major Cloud Groups and Their Types 1 High clouds 3 Low clouds g ir39 1 Ci Stratus St Cirrostratus Cs Stratucumulus Sc in39gcumulus Cc Nimbostmtus Ns 4 Clouds with vertical development mm Cumulonimbus Cb 2 Middle clouds Altnstratus As Altocumulus Ac amt 53 H J LOUD GROUP TROPILM REGION MIDDLE LAmqu 050100 10000 in 60000 ft 10000 i043000139i High Ci Cs Cc 0000 m 10000 mi 5000 lo 13000 m Middl 6500 to 20000 1 0500 to 3000 ft AsA 2000 to 0000 m 2000 m 7000 in same i0 6500 11 surface in 0500 n 00200001 0 m 2000 m mum mmm HigherEducalmn Cloud base height changes with latitude POLAR 0510quot 10000 10 20000 ll 3000018000 nl 5500 to 13000 R 2000 to 4000 m surface in 500 0 m 1000 m High Clouds Cirrus Ci High clouds are comprised largely of ice Cloudbase heights for high clouds Tropical Region 6 18 km Middle Latitudes 5 13 km Polar Regions 3 8 km Cirrus Clouds high thin wispy clouds up at jet stream level in the upper troposphere They are almost always comprised of ice associated with fair weather Cirrostraz us Clouds High thin sheetlike clouds Produce halos around the sunmoon Rain or snow is often 1224 hours away Cirrocumulus clouds High thin clouds appear as small rounded white puffs May occur individually or in long rows When in royys is has a rippling appearance Middle Clouds Altocumulus Ac Middle clouds are composed of water andor ice Cloudbase heights for middle clouds Tropical Region 28 km Middle Latitudes 27 km Polar Regions 24 km Altocumulus Clouds shallow puffy or wavelike in appearance appear the size of I your thumbnail when holding your arm up to the sky Middle Clouds Altostratus As Altostratus Clouds grayishbluegray thin layer covering entire sky uniformly found ahead of storms can seen the sun through altostratus but NO halo wil 5 5 eryegl Low Clouds stratus St Cloudbase heights for middle clouds Tropical Region 02 km Middle Latitudes 02 km Polar Regions 02 km Stratus Clouds Uniform grayish cloud covering the entire 5 Common in the Northeast Kingdom Low Clouds Nimbostratus Ns Nimbostratus Clouds darker gray quotwetquot looking low clouds they produce lightmoderate precipitation over a on large regi Low Clouds Stratocumulus Sc Stratocumulus Clouds low lumpy puffy clouds in patches or rounded masses Visually appear largerthan altocumulus Appear the size of your fist when holding your arm up to the sky Vertically Developed Clouds Cumulus Cu Cumulus Clouds Look like cotton ballscauliflower in the sky sub categories of cumulus cumulus humilis slightly developed Cu cumulus congestus moderately developed Vertically Developed Clouds Cumulonimbus Cb Cumulonimbus Clouds thunderstorms develop from growing Cu can extend up to the troposphere can contain both water and ice contains precipitation rain snow hail etc produce lightning and severe weather form a distinctive quotanvilquot cloud at the top of the storm TA B LE 54 CommnulTermswsgd in Idgn fylng Clouds mm mm mm AND MEANING nBCllle m Urns lwlll rlllll lumill with wellttlclinutl uulllllt st This lcrln lpplius mtllllly In clnmtmuhls ul lummuhls and slntluchmhlus chlus fmllg 39c lo hm k or fracture Clouds that have ll rugged or turn appearance applies only to strains and Humilis tlnmults hl39shhtll size Cumulus clouds with generally llallcnud buses and slight Vcrlicdl gmwlh Congeslus I s w v 39 39 39 39 head ul39cttttlillnwcr Lt vus t39llllllsv hilldl 39 39 its cumulilnrm mlllin Cztpillnlus rapilllls lmtulmving hair Cumulonimbuschamelchanbylltcpmscucein hcuppcrpar nl clrtlrurm clnu s with bmtts or slrinlcd slructuttz Undululus thmlh wave hhving waves clouds in patches sheets or layers shhwhlg undulations Irmlsluci dus fquot 39 L 39 reveal the posiliml hr the sun or moon anm illmi anvill Kim is anvilshaped Mhnmutus mmllmllmanunary occur with cirrus allocumulus nlloslmtus xu hltlcumulus and anulonim Pileus Pilclls my 39 h cumulil m m clmld ptlrlicularly during ils develulih lgsldgi Castellanns t um39lllml n mlz nap in llivihmw nfltmnll may Summary of Cloud Types Anvil up Other unusual clouds Lenticular Clouds Lenticular Clouds form as air flows over mountains look like pancakes UFOs even Other unusual clouds Cap Cloud Cap Cloud forms as air is forced up and over a mountain Other unusual clouds Pileus Pileus forms as a growing thunderstorm deflects moist air up and over the top of the building cumulus congestus or cumulonimbus Other unusual clouds Mammatus Mammatus look like cow39s udder visually very impressive usually form underneath Cb visual manifestation of sinkin air not risin air Other unusual clouds Contrails Contrails are formed from the exhaust of high flying aircraft are similar in makeup to cirrus clouds have an important impact on the radiation balance for the earth Nacreous clouds They form in the stratosphere and are most easily seen at high latitudes Noctilucent clouds They are usually observed at high latitudes at altitudes between 75 and 90 km above the earth s surface Other unusual clouds Scud Scud ragged low clouds beneath actual cloud base Often form due to turbulent mixing of air warm air from the updraft cool air from the downdraft GroundBased Description of Sky Conditions TAB LE E 5 Description of Sky Cnndltions aasmmuu uzscmmow ASUS39 HUMAN MEANING Clear lCLR m39 SKCI l in 5 l1 Nn cloud Few gt5 lo 525 a 0 4 Few clouds visible Summ t d sci gt1 u saw 394 u v Pmly inudy Bmken BKN I gt50 lo 587 m 74 Muslly cloudy UVCI CHM KWC gt 7 u NWn sky is waxed by clouds Sky obscured 7 7 5qu is hidden by sul39thbased pheuomeuu such as rag blowing snum smoke and so term mum um by cloud cover a 2mm Thomsan Higher Educalian 23 Cloud base measurements with laser ceilometer Cloud base 4 V 0 5000 ft 5 Indicator Laser ceilometer Satellite Observations of Clouds First Meteorological Satellites were launched in late 195039s Today we use two types of satellites to monitor weather Geostationary Polar orbiting Geostationary Satellites GOES Geostationary satellites are positioned over the equator They orbit the earth at the same rate as the earths rotation This allows for a continuous View of the same location The US has two geostationary satellites GOESE gtgt located at 0 N 75 W GOESWgtgt located at 0 N 135 W 25 Q What are the advantages and disadvantages of the GOES satellites Polar Orbiting Satellites Orbit in a nearly NS manner around the globe Nearly pass over the poles 1 orbit takes about 120 minutes Q What are the advantages and disadvantages ofthe polar orbiting satellites Types of Satellite Data Satellites collect two primary types of meteorological imagery Visible basically a picture ofthe clouds much like taking a picture with your camera Infrared tells you the temperature of what the satellite is sensing whether its the ground or the tops of clouds very useful for determining the height of the cloud low middle high Inhaled saielllle image f l r r 39 Armani While in Satellite W lt lnlrared energy Cold ltltltlt Low cloud High cloud 27 A visible image of the eastern Pacific our 3 Tyniual Albedovf various Surfaces SURFACE Maine anrnn Fqu unm 75 In 05 Clouds Mick no lo 90 Cluuds tlllin 0 In so Vents 78 Ice 30 m 40 Sand I5 lo 45 Earth and auuosplmc 50 Man 17 Grassy rld mm 30 Dry puma eld 5 m 20 er IO Form 3 in ID Moon 7 Dnyuwmga Ocean surface temperature measurements with satellite a 2nn7mman Hanan4cm Get Hurricane cloud and precipitation structure from Satellite V HUMANS FLOVDONWG nation was 6 quotquot mam Hydrogen HYd39OQE n 391 5amp6quot Oxygen l i o i 1 The partially exposed hydrogen atom of one molecule is attracted to the negative oxygen atom of another molecule Because the hydrogen atoms of each water molecule are separated by an angle of 105 the joining of many billions of molecules produces a hexagonalshaped ice crystal Water Phase Changes Sublimation icetovapor phase change Deposition vaportoice change Evaporation liquidtovapor change Condensation vaportoliquid change Melting Freezing Energy release or absorption associated with water phase changes Saturation All else being cool water ta Vvalel quot the water 39 39 Hum quuiu into vapor 39 39 Hum pul imu liquid 39 39 39 evaporating than condensing net evaporation is occurring b When the number of we r I r condensing the air L L 39 39 39 39th watervapor Condensation is more likely to occur as the air cools WAFlM AIR COOL AlFl Condensation nuclei or Cloud condensation nuclei CCN a In the warm air 39 colliding with nuclei b In the cool air slowmoving vapor molecules are more likely to join together on nuclei Tquot 39 39 39 tiny liquid water droplets Conclusion based on last two slides Warm air can hold more water vapor molecules before becoming saturated than cold air Or warm air has a greater capacity for water vapor than does cold air Circulation of Water in the Atmosphere The Hydrologic Cycle The water substance is critical for our survival on this planet Very important for creating weather Very important for transporting heat Very important for every living plants on Earth Water cycle animation Processes in the hydrologic cycle evaporation transpiration condensation precipitation run off Evaporation and condensation in the Atmosphere Consider the ocean surface If evaporation rate gt condensation rate the air above the cean Is subsaturated supersaturated saturated If evaporation rate condensation rate the air above the ocean is subsaturated supersaturated saturated If evaporation rate lt condensation rate the air above the ocean is subsaturated supersaturated saturated M oisture Variables There are a number of ways one can specify the amount of moisture referred to as humidity in the air What are they mm Absolute humidity quotWquot specific humidity M4 3 vapor pressure and saturation vapor pressure 4 relative humidity 5 mixing ratio and saturation mixing ratio 6 wetbulb temperature rpm 7 dewpoint temperature Let39s look at each of these more carefully Absolute Humidity The Absolute Humidity of a parcel of air is expressed as Absolute Humidity mass of water vapor volume ofair 80 Absolute Humidity is like a water vapor density commonly express in grams m3 ls Absolute Humidity a good variable to use for measuring moisture in air What happens to the volume of a rising or sinking air parcel Consider a parcel of air at 1000mb The parcel will exert 1000 mb of pressure to counteract the atmospheric pressure acting on the parcel Recall that Pressure ForceArea If no energy is added or taken away from the parcel then the force of the molecules bumping into the side of the parcel will be constant ie Force Pressure xArea const The parcel rises to 500 mb since Force Pressure xArea const I then since the pressure decreases as it a rises the area of the parcel must increase orthe parcel expands Absolute Humidity is it a good variable to measure humidity Consider a parcel of air that is rising and expanding Recall that absolute humidity mass of H20 volume Q does the amount of moisture in the parcel change as it nses Q is the absolute humidity constant as the parcel rises 80 is absolute humidity a good moisture variable Miss quotimam Hurrale H20er 5 gl39n3 10 gm3 Specific Humidity Speci c humidity is defined as specific humidity mass of water vaportotal mass of air Example in a given parcel the mass of water vapor is 1 g the total mass ofthe parcel N2 02 AR H20 othertrace gasses is 1 kg then the specific humidity is Q what will the latitudinal distribution of specific humidity 0 Innh hn The average specific humidity for each latitude The highest average values are observed in the tropics and the lowest values in polar regions SpeCilic Humidity gkg 0 l l l l l 60quot 50quot 400 30 20 10 O 10 20quot SQL 40 50 ESOU Norih Laiiiude South Mixing Ratio Mixing ratio is defined as mixing ratio mass of water vapor mass of dry air Example in a given parcel the mass of water vapor is 1 g the mass of dry air in the parcel N2 02 AR other trace gasses is 10 kg then the mixing ratio is The difference with specific humidity specific humidity mass of water vaportotal mass of air Vapor Pressure Given a parcel of air comprised of only nitrogen oxygen and water vapor The total pressure of the air parcel is due to the sum of quotpartial pressuresquot of each of the gasses comprising the parcel The partial pressure due to water vapor is called the quotvapor pressure The correlation of vapor pressure with numbers of water vapor molecules I Plum 7 mml m mih V l Hi i m um mm Him puma immune in mer raptr Immun Saturation Vapor Pressure When an air parcel is saturated gtgt the vapor 4 u m pressure is then the saturation vapor pressure Saturation vapor pressure is dependent on the temperature of a gas according the graph to the right For an unsaturated parcel of air at a given temperature there are two ways to saturate it where the vapor pressure will then equal the saturation vapor pressure what are they Saturation Vapor Q When will water boil When saturation water Vapor pressure over water is e ual atmospheric pressure Q Why is the boiling point lower in Denver CO than in San Francisco CA Q So where would vegetables require more time to cook Denver or San Francisco F Vessuve mbl Boiling Point Pressure and the 7 ailing new a 92 c i 39 lzvaivon 240v m I 750 E av 92 93 94 as 7 92 99 mini 95 9 Bailing Pew Tempevame 0 moisture of water vapor actually in the saturation at that particular te pressure Two different way to measure saturation vapor pressure saturation mixing ratio Relative Humidity Most common variable used to describe atmospheric The relative humidity RH is the ratio of the amount maximum amount of water vapor required for RH water vapor content water vapor capacity air compared to the mperature and water vapor capacity Vapor premw e 7 x 1 00 percent mmmnan Vapor presmme actual mum HZIZU gx100 percent saturatmn mmng ratzu Two primary ways to change RH 1 By changing the air s water vapor content A water vapor is add to the air with no change in air temperature the RH er vapor is removed from the air the RH decreases 2 By changing the air Mum temperature With no change in water vapor content an increase in air temperature lowers the RH while a decrease in air temperature raises the RH Diurnal Variation of Relative Humidity Q Given that the amount of moisture at a particular location is constant during a 24 hour day ie the mixing ratio is constant then what will the diurnal variation of RH look like Q Why does this happen Q When is the best time to water your lawn to minim39ze evaporation Q Why do your lips seem so dry in Relatrve humidity Temperature Temperature winter Relative Humidity 8 Mldlllgl39ll 600 A M Noon 5 00 PM MIK lUIQh Q On a given day in winter is the RH larger in a house or outside Q Is the evaporation rate greater inside the house or outside DewPoint Temperature m in 71 U C1 Temperature to which one must cool air for it to reach saturation It39s a pretty good approximation to amount of vapor in air The difference between T Td is proportional to n the relative humidity W m m E D J i F1 39r 4 M 37 Ti E5 5 1131 Te39t iridium M We NW mm quotTABLE 1 Saturation Vapor Pressure Over Water for Various Air Temperatures SATURATION SATURATION AIR TEMPERATURE VAPOR AIR TEMPERAYURE VAPOR C F PRESSURE ac vr PRESSURE M8 MB 718 0 L5 18 65 210 15 5 19 21 70 25 ill 10 24 24 75 296 9 15gt 30 27 180 350 7 20 3 19 SS 4 4 25 45 32 90 481 1 301 56 35 95 562 2 35 69 38 100 656 4 40 84 41 105 702 7 45 102 43 110 878 10 50 123 46 115 1014 13 55 148 49 120 1168 16 L60 177 52 125 1542 Physically explain the quotmeanquot dew point temperature maps for January and July to the right or lillY The polar air has the higher relative humidity whereas the desert air with the higher dew point contains more water vapor Relative humidity averaged for latitudes north and south of the equator 90 5 b 80 E E I i g 70 7 I I 0 I I 60 I I i I i I I 60 40 20 0 20 40 North Latitude South n ma mm rm MN Comparing Humidities t a V PaoriaL 80 F SacramentoCA Tu 70quotF Philadelphia PA 55 T W HH 72 T S30 rs C 7 53 Ta 73 F H 121 RH 72 Water temperature Hot and dry HIgh lemperature L ew point 5 Low relative humldity Cooi aii quot39 LimenuckAK T 2 91 F rd 2 F RH 57 iquot 7 74 F rd 55 F HH 58 24 e BODF 439 HH r gm i 86 We er temperature 3 thCi r i SUMMER 2am mmm may Education How to change RH in the home Relative Humidity in the home V INSlDE AIR OUTSIDE Al 39 r 20quot0 55quotFl r r5quotc 5 F V T45 r5 a T45 C5 F HH 8 RH 100 l Wet Bulb Temperature The lowest temperature that can be reached by evaporating water into the air Note the wet bulb temperature will always be less than or equal to the temperature Example lfyou are a runner T 90 F RH 90 gt high wetbulb temp T 90 F RH 10 gt low wetbulb temp Feel more comfortable when wetbulb temperature is low Wetbulb temperature is related to the heat index gtgt Ir lemperature r Heat index HI combines air temperature with RH to determine an apparent temperature what the air temperature feels likequot to average person for various combinations of air temperature and RH Relative Humidity 70 5 TO 15 20 25 30 35 40 45 50 55 60 65 7O 75 BO 85 90 95 100 so 130 54 E 120 49 e 1 2 E 110 gt an g 3 1 3 5 5 100 x a 38 3 lt i 90 32 80 IV Very warm 807 27 l i i i Heat Index HI apparent temperature FM 7D A r i l 0 10 20 30 4o 50 so 70 80 90 100 Relative Humidity 96 The HI as a function of air temperature and RH APPARENT CATEGORY TEMPERATURE F HEAT SYNDROME I 130 or higher Heatstroke or sunstroke imminent II 105 130 Sunstroke heat cramps or heat ex haustion likely heatstroke possible with prolonged exposure and physical activity III 90 105 Sunstroke heat cramps and heat exhaustion possible with prolonged exposure and physical activity IV 80 90 Fatigue possible with prolonged ex posure and physical activity Measuring Humidity Sling Psychrometer The Sling Psychrometer is a common instrument used to obtain a measurement ofthe dew point temperature By measuring wet bulb temperature and air temperature Wet bulb The hair hydrometer measures RH by amplifying and measuring changes in the length of human or horse hair Record paper on cyiinder o lt7 Amplifying levers 4 i Exposed human hairs 3 Compensating cams I J D Adjusting screw ls humid air or dry air more dense TABLE 2 as i Mo ifEcggi yjfd 39fr i i i l 16 32 X 21 z 7 134 28 Molecular weight of dry air z 29 a zumnman therEducuoun SUMMARY OF MOISTURE VARIABLES absolute humidity specific humidity mixing ratio saturation mixing ratio vapor pressure saturation vapor pressure relative humidity wetbulb temperature dewpoint temperature
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