Introduction to Climatology

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© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Chapter 1Introduction to Climatology © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION those specializingNOT FOR in glaciology, SALE OR as wellDISTRIBUTION as special- Chapter at a Glance ized physical geographers, geologists, and ocean- Meteorology and Climatology ographers. The biosphere, which crosscuts the Scales in Climatology lithosphere, hydrosphere, cryosphere, and atmo- Subfields of Climatology sphere, includes the zone containing all life forms © Jones & BartlettClimatic Learning, Records andLLC Statistics © Joneson the& Bartlettplanet, including Learning, humans. LLC The biosphere NOT FOR SALE SummaryOR DISTRIBUTION NOT FORis examined SALE by OR specialists DISTRIBUTION in the wide array of life Key Terms sciences, along with physical geographers, geolo- Review Questions gists, and other environmental scientists. Questions for Thought The atmosphere is the component of the system © Jones & Bartlett Learning, LLCstudied by climatologists ©and Jones meteorologists. & Bartlett Ho- Learning, LLC NOT FOR SALE OR DISTRIBUTIONlistic interactions betweenNOT the FORatmosphere SALE and OR DISTRIBUTION Climatology may be described as the scientific each combination of the “spheres” are important study of the behavior of the atmosphere—the contributors to the climate (Table 1.1), at scales thin gaseous layer surrounding Earth’s surface— from local to planetary. Thus, climatologists must integrated over time. Although this definition is draw on knowledge generated in several natural © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC certainly acceptable, it fails to capture fully the and sometimes social scientific disciplines to un- NOTscope FOR of SALE climatology. OR DISTRIBUTION Climatology is a holistic derstandNOT the processes FOR SALE at work OR in the DISTRIBUTION atmosphere. science that incorporates data, ideas, and theo- Because of its holistic nature of atmospheric prop- ries from all parts of the Earth–ocean–atmosphere erties over time and space, climatology naturally system, including those influenced by humans, falls into the broader discipline of geography. © Jones & Bartlettinto Learning, an integrated LLC whole to explain atmospheric© Jones Over & Bartlett the course Learning, of this book LLC we shall see that these processes can be complex. The effects of NOT FOR SALE properties.OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION The Earth–ocean–atmosphere system may be some of these interactions cascade up from local divided into a number of zones, with each tradi- to planetary scales, and the effects of others tend tionally studied by a separate scientific discipline. to cascade down the various scales to ultimately The part of the solid Earth nearest to the surface (to affect individual locations over time. The processes a depth of perhaps© Jones 100 & km) Bartlett is called Learning, the litho- LLCare so interrelated with other© Jones spheres & Bartlettand with Learning, LLC sphere and NOTis studied FOR by geologists,SALE OR geophysicists, DISTRIBUTION other scales that it is often NOTdifficult FOR to generalizeSALE OR by DISTRIBUTION geomorphologists, soil scientists, vulcanologists, saying that any particular impact begins at one and other practitioners of the environmental and component of the system or side of the scale and agricultural sciences. The part of the system that is proceeds to another. © Jonescovered & by Bartlett liquid water Learning, is termed theLLC hydrosphere; We can© stateJones that & the Bartlett scope of Learning, climatology LLC is it is considered by those in the fields of oceanogra- broad. It has also expanded widely from its roots NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION phy, hydrology, and limnology (the study of lakes). in ancient Greece. The term “climatology” is de- The region comprising frozen water in all its forms rived from the Greek term “klima,” which means (glaciers, sea ice, surface and subsurface ice, and “slope,” and reflects the early idea that distance snow) is known as the cryosphere and is studied by from the equator alone (which causes differences © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE2 OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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Meteorology and Climatology 3

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Table 1.1 Examples of Interactions Between the AtmosphereNOT and FORthe Other SALE “Spheres” OR and DISTRIBUTION Impacts NOT FOR SALEon Thermal OR Receipt/ClimateDISTRIBUTION

Sphere Interacting with Atmosphere Example of a Potential Impact

Lithosphere Large volcanic eruptions can create a dust and soot cloud that can reduce the receipt © Jones & Bartlettof solar Learning,radiation, cooling LLC the global atmosphere for months or© years. Jones & Bartlett Learning, LLC Hydrosphere NOT FOR SALEChanges OR inDISTRIBUTION ocean circulation can cause global atmospheric circulationNOT FOR shifts that SALE OR DISTRIBUTION produce warming in some regions and cooling in others. Cryosphere Melting of polar ice caps can cause extra heating at the surface where ice was located because bare ground reflects less of the solar energy incident upon the surface than ice. Biosphere© Jones & Bartlett Learning,Deforestation LLC increases the amount of solar© Jones energy received & Bartlett at the surface Learning, and alters LLC atmospheric chemistry by returning carbon dioxide stored in living plant matter to NOT FOR SALE OR DISTRIBUTIONthe atmosphere. NOT FOR SALE OR DISTRIBUTION

in the angle or slope of the Sun in the sky) drove meteorology involves only the present, the imme- climate. The second part of the word is derived diate past, and the very near future. © Jones & Bartlettfrom “logos,” Learning, defined asLLC “study” or “discourse.” Mod- © JonesBut a much & Bartlett more important Learning, component LLC of me- NOT FOR SALEern climatology OR DISTRIBUTION seeks not only to describe the na- NOTteorology FOR is SALE the examination OR DISTRIBUTION of the forces that cre- ture of the atmosphere from location to location ate the atmospheric properties being measured. over many different time scales but also to explain Changes in the magnitude or direction of these why particular attributes occur and change over forces over time and changes in the internal prop- time and to assess© theJones potential & Bartlett impacts ofLearning, those erties LLC of the matter being affected© Jones by these & forces Bartlett Learning, LLC changes on naturalNOT and socialFOR systems. SALE OR DISTRIBUTIONcreate differences in weather conditionsNOT FOR over SALE time. OR DISTRIBUTION Although many meteorologists are not directly ■■Meteorology and Climatology involved with forecasting these changes, meteo rology is the only natural science in which a pri- The two atmospheric sciences, meteorology and mary goal is to predict future conditions. Weather climatology,© Jones & are Bartlett inherently Learning, linked. Meteorology LLC forecasting has© improved Jones greatly& Bartlett with recent Learning, tech- LLC isNOT the studyFOR ofSALE weather OR—the DISTRIBUTION overall instanta- nological enhancementsNOT FOR that SALE allow ORfor improvedDISTRIBUTION neous condition of the atmosphere at a certain understanding of these forces, along with improved place and time. Weather is described through the observation, data collection, and modeling of the direct measurement of particular atmospheric atmosphere. Currently, weather forecasts pro- © Jones & Bartlettproperties Learning, such as temperature,LLC precipitation, © ducedJones by & the Bartlett National Learning, Weather Service LLC in the humidity, wind direction, wind speed, cloud United States are accurate for most locations over a NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION cover, and cloud type. The term “weather” refers period of approximately 72 hours. to tangible aspects of the atmosphere. A quick By contrast, climate refers to the state of the look or walk outside may be all that is needed to atmosphere for a given place over time. It is im- describe the weather of your location. Of course, portant to note that climatologists are indeed con- these observations© Jonesmay be &compared Bartlett with Learning, the cerned LLC with the same atmospheric© Jones processes & Bartlettthat Learning, LLC state of the atmosphereNOT FORat other SALE locations, OR whichDISTRIBUTION meteorologists study, but the NOTscope FORis different. SALE OR DISTRIBUTION in most cases is different. Meteorologists may study the processes for their Because meteorology deals with direct and spe- own sake, while climatologists study the processes cific measurements of atmospheric properties, dis- to understand the long-term consequences of cussion© Jones of weather & Bartlett centers Learning, on short-duration LLC time those processes.© Jones Climatology, & Bartlett therefore, Learning, allows LLC intervals. Weather is generally discussed over time us to study atmospheric processes and their im- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION spans of a few days at most. How is the weather pacts far beyond present-day weather. today? How does this compare with the weather we There are three properties of climate data to con- had yesterday? What will the weather be like to- sider: normals, extremes, and frequencies. These morrow or toward the end of the week? All of these are used to gauge the state of the atmosphere over a © Jones & Bartlettquestions Learning, involve short-term LLC analysis of atmo- © particularJones & time Bartlett period Learning, as compared LLC with atmo- NOT FOR SALEspheric OR properties DISTRIBUTION for a given time and place. So NOTspheric FOR conditions SALE over OR a DISTRIBUTION similar time period in the

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4 Chapter 1 — Introduction to Climatology

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE past.OR DISTRIBUTIONNormals refer to average weather conditionsNOT FORbut also SALE in the OR other DISTRIBUTION “spheres” because the interac- at a place. Climatic normals are typically calculated tions between the atmosphere and the other spheres for 30-year periods and give a view of the type of ex- are more likely to have important consequences pected weather conditions for a location through over longer, rather than shorter, time scales. This is the course of a year. For example, climatologically particularly true if those processes occur over large normal conditions© Jones in Crestview,& Bartlett Florida, Learning, are hot LLC areas, because the impacts© usuallyJones take & Bartlett longer to Learning, LLC and humid NOTduring FOR the summer SALE andOR coolDISTRIBUTION but not develop in such cases. ForNOT instance, FOR ifSALE the Great OR DISTRIBUTION cold in winter. Lakes were to totally evaporate, such a process Two places could have the same average condi- would necessarily take place over a long time pe- tions but with different ranges of those conditions, riod. The difference in water level in the Great Lakes © Jonesin the same& Bartlett way that Learning, two students LLC who both have between ©today Jones and &tomorrow Bartlett would Learning, not cause LLC NOTan FOR average SALE of 85 percentOR DISTRIBUTION in a class may not have ac- much impactNOT on FOR tomorrow’s SALE weather OR DISTRIBUTION as compared quired that average by earning the same score on with today’s. A meteorologist would, therefore, not each graded assignment. Therefore, extremes are really need to take this atmosphere–hydrosphere used to describe the maximum and minimum interaction into account when considering tomor- measurements of atmospheric variables that can row’s weather. However, the difference in water © Jones & Bartlettbe expectedLearning, to occur LLC at a certain place and time,© Jones content & Bartlett between Learning,the Great Lakes LLC over centuries is NOT FOR SALE basedOR DISTRIBUTION on a long period of observations. For examNOT- FORmore SALElikely to ORhave DISTRIBUTION a noticeable and dramatic im- ple, a temperature of 0°C (32°F) at Crestview in pact on climate during that time period. Interac- April would fall outside of the range of expected tions between the atmosphere and other spheres, temperatures. such as in this example, thus must be considered Finally, frequencies© Jones & refer Bartlett to the Learning,rate of inci- LLCwhen evaluating climate. © Jones & Bartlett Learning, LLC dence of a particularNOT FOR phenomenon SALE OR at aDISTRIBUTION particular Regardless of the differencesNOT FOR between SALE meteo OR DISTRIBUTION place over a long period of time. Frequency data rology and climatology, it is important to recognize are often important for risk assessment, engineer- that the distinction between the two is becoming ing, or agricultural applications. For instance, the increasingly blurred over time. A successful clima- frequency of hailstorms in a city is a factor in de- tologist should have a firm grounding in the laws of © Jonestermining & Bartlett a homeowner’s Learning, insurance LLC premium. Or atmospheric© Jones physics &and Bartlett chemistry Learning, that dictate theLLC NOTif FORan engineer SALE designs OR DISTRIBUTION a culvert to accommodate instantaneousNOT behaviorFOR SALE of the ORatmosphere. DISTRIBUTION An ef- 8 cm (3 in.) of rain in a 5-hour period but that fre- fective meteorologist should recognize the impor- quency is exceeded an average of two times per tance of patterns over time and the impacts of those year, this rate of failure may or may not be accept- patterns and the influence of other components of © Jones & Bartlettable Learning, to the citizens LLC affected by the culvert. A farmer© Jones the Earth–ocean–atmosphere& Bartlett Learning, system. LLC may want to know how many days on average have The holistic perspective of climatology also car- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION more than 1.5 cm (0.6 in.) of rain in October be- ries over to include interactions between the atmo- cause October rains are problematic for any crop sphere and social systems. The impact of people on harvested during that month. their environment is a theme in climatology that We can say then that both meteorologists and has become more prevalent in recent years. It is climatologists© Jonesstudy the & sameBartlett atmospheric Learning, pro- LLCbeing increasingly recognized© Jones that many & Bartlett features Learning, LLC cesses but withNOT three FOR primary SALE and OR important DISTRIBUTION dif- of the human condition areNOT related FOR to climate. SALE This OR DISTRIBUTION ferences. First, the time scales involved are is especially true of climatic “extremes” and “fre- different. Meteorologists are primarily concerned quencies,” because it is the “abnormal” events, and with features of the atmosphere at a particular time conditions exceeding certain thresholds, that gen- © Jonesand place—the & Bartlett “weather”—whereas Learning, LLC climatologists erally cause© Jones the greatest & Bartlett impact on Learning, individuals andLLC study the long-term patterns and trends of those society. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION short-term features—the “climate.” Second, meteorologists are more concerned with the processes for ■■Scales in Climatology their own sake, while climatologists consider the long-term implications of those processes. Third, We have already stated the importance of tempo- © Jones & Bartlettclimatology Learning, is inherently LLC more intertwined ©with Jones ral scale& Bartlett in climatology. Learning, It is LLC also important to NOT FOR SALE processesOR DISTRIBUTION happening not only in the atmosphereNOT FORemphasize SALE that OR climatology DISTRIBUTION involves the study of

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Subfields of Climatology 5

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEatmospheric OR DISTRIBUTION phenomena along many differentNOT with FOR their associatedSALE OR fronts DISTRIBUTION fall into the synoptic spatial scales. There is usually a direct relation- scale. Because these phenomena are quite fre- ship between the size of individual atmospheric quent and directly affect many people, the synop- phenomena and the time scale in which that phe- tic scale is perhaps the most studied spatial scale nomenon occurs (Figure 1.1). The microscale in the atmospheric sciences. represents the smallest© Jones of all & atmospheric Bartlett Learning, scales. LLCFinally, we can also study and© view Jones climate & Bartlettover Learning, LLC Phenomena that NOToperate FOR along SALE this spatial OR DISTRIBUTION scale an entire hemisphere or evenNOT the entire FOR globe.SALE OR DISTRIBUTION are smaller than 0.5 km (0.3 mi) and typically last This represents the largest spatial scale possible from a few seconds to a few hours. A tiny circula- and is termed the planetary scale, because it en- tion between the underside and the top of an indi- compasses atmospheric phenomena on the order of vidual© Jones leaf &falls Bartlett into this Learning, category, LLCas does a 10,000 to 40,000© km Jones (6000 to& 24,000 Bartlett mi). BecauseLearning, in LLC tornadoNOT FOR funnel SALE cloud, ORand everythingDISTRIBUTION between. A general the largestNOT spatial FOR systems SALE operate OR DISTRIBUTION over the larger scale is the local scale, which operates over longest time scales, it is no surprise then that plane- areas between about 0.5 and 5 km (0.3 to 3 mi)— tary-scale systems operate over temporal scales that about the size of a small town. A typical thunder- span weeks to months. Examples of planetary-scale storm falls into this spatial scale. systems include the broad wavelike flow in the up- © Jones & BartlettThe nextLearning, spatial scale LLC is the mesoscale, which © perJones atmosphere & Bartlett and the Learning, major latitudinal LLC pressure NOT FOR SALEinvolves OR systems DISTRIBUTION that operate over areas between NOTand windFOR belts SALE that ORencircle DISTRIBUTION the planet. about 5 and 100 km (3 to 60 mi) and typically last from a few hours to a few days. Such systems include ■■Subfields of Climatology those you may have encountered in earlier course- work, such as the mountain/valley© Jones & Bartlett breeze and Learning, land/ Climatolo LLC gy can be divided into© several Jones subfields, & Bartlett Learning, LLC sea breeze circulationNOT systems, FOR SALEclusters ORof interact DISTRIBUTION- some of which correspond to certainNOT scales FOR of SALEanal- OR DISTRIBUTION ing thunderstorms known as mesoscale convective ysis. For instance, the study of the microscale pro- complexes, a related phenomenon associated with cesses involving interactions between the lower cold fronts termed “mesoscale convective systems,” atmosphere and the local surface falls into the and the central region of a hurricane. realm of boundary-layer climatology. This subfield © MovingJones toward & Bartlett larger phenomena,Learning, weLLC come to is primarily concerned© Jones with & Bartlettexchanges Learning,in energy, LLC theNOT synoptic FOR scaleSALE, a spatialOR DISTRIBUTION scale of analysis that matter (especiallyNOT water), FOR and SALE momentum OR DISTRIBUTION near the functions over areas between 100 and 10,000 km surface. Physical processes can become very com- (60 to 6000 mi). Systems of this size typically oper- plex in the near-surface “boundary layer” for two ate over periods of days to weeks. Entire tropical reasons. First, the decreasing effect of friction from © Jones & Bartlettcyclone systems Learning, and midlatitude LLC (frontal) cyclones © theJones surface & upwardBartlett complicates Learning, the LLCmotion of the NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Atmospheric planetary waves 106 Midlatitude cyclone Hurricane 105 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONLand/sea breeze NOT FOR SALE OR DISTRIBUTION 104 Thunderstorm Tornado 103 Dust devil 102 Turbulence in an urban city street © JonesMicroturbulence & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Temporal Scale (seconds) Temporal NOT101 FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Micro Local Meso Synoptic Planetary 100 .00001 .0001 .001 .01 .1 1 10 100 1,000 10,000 100,000

© Jones & Bartlett Learning, LLC Spatial© Jones Scale (km) & Bartlett Learning, LLC NOT FOR SALEFigure OR 1.1 DISTRIBUTIONSpatial–temporal relationships for selected atmosphericNOT FOR features. SALE OR DISTRIBUTION

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6 Chapter 1 — Introduction to Climatology

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE atmosphereOR DISTRIBUTION and involves significant transferNOT of FORand theSALE surface OR environmentDISTRIBUTION of a region.” He momentum downward to the surface. Second, the goes on to state that, “because synoptic climatol- most vigorous exchanges of energy and moisture ogy seeks to explain key interactions between occur in this layer because solar radiant energy the atmosphere and surface environment, it has striking the ground warms it greatly and rapidly great potential for basic and applied research in compared with© Jones the atmosphere & Bartlett above Learning, it and be- LLCthe environmental sciences.”© Jones Synoptic & Bartlett climatol- Learning, LLC cause the sourceNOT of FOR water SALE for evaporation OR DISTRIBUTION is at the ogy may act as a keystoneNOT that linksFOR studies SALE of ORat- DISTRIBUTION surface. Boundary-layer climatology may be fur- mospheric dynamics with applications in various ther subdivided into topics that examine surface– other disciplines. atmosphere interactions in mountain/alpine re- Synoptic climatology is similar in some ways to © Jonesgions, &urban Bartlett landscapes, Learning, or various LLC vegetated regional ©climatology Jones &, aBartlett description Learning, of the climate LLC NOTland FOR covers. SALE OR DISTRIBUTION of a particularNOT region FOR of SALE the surface. OR DISTRIBUTIONHowever, syn- Physical climatology is related to boundary- optic climatology necessarily involves the expla- layer climatology in that it studies energy and mat- nation of process, whereas regional climatology ter. However, it differs in that it emphasizes the may not. nature of atmospheric energy and matter them- The study of climate can extend to times before © Jones & Bartlettselves Learning, at climatic LLC time scales, rather than the© pro Jones- the advent& Bartlett of the instrumentalLearning, weatherLLC record. This NOT FOR SALE cessesOR DISTRIBUTION involving energy, matter, and momentumNOT FORsubfield SALE of climatology OR DISTRIBUTION is termed paleoclimatology exchanges only in the near-surface atmosphere. and involves the extraction of climatic data from Some examples include studies on the causes of indirect sources. This proxy evidence may include lightning, atmospheric optical effects, microphysics human sources such as books, journals, diaries, of cloud formation,© Jones and air& Bartlettpollution. AlthoughLearning, me- LLCnewspapers, and artwork to© gain Jones information & Bartlett about Learning, LLC teorology hasNOT traditionally FOR SALE emphasized OR DISTRIBUTION this type of preinstrumental climates.NOT However, FOR the SALE field ORpri- DISTRIBUTION work to a greater extent than climatology, climatol- marily focuses on biological, geological, geochemi- ogists have contributed to our understanding of cal, and geophysical proxy sources, such as the these phenomena. Furthermore, the convergence analysis of tree rings, fossils, corals, pollen, ice of meteorology and climatology as disciplines will cores, striations in rocks, and sediment deposited © Joneslikely lead& Bartlett to more Learning,overlap in these LLC topics of re- annually ©on Jones the bottoms & Bartlett of lakes (varves Learning,). LLC NOTsearch FOR in SALE the future. OR DISTRIBUTION BioclimatologyNOT FOR is SALEa very diverse OR DISTRIBUTION subfield that Hydroclimatology involves the processes (at includes the interaction of living things with their all spatial scales) of interaction between the atmo- atmospheric environment. Agricultural climatol- sphere and near-surface water in solid, liquid, and ogy is the branch of bioclimatology that deals with © Jones & Bartlettgaseous Learning, forms. This LLC subfield analyzes all compo© Jones- the impact& Bartlett of atmospheric Learning, properties LLC and processes nents of the global hydrologic cycle. Hydrocli- on living things of economic value. Human biocli- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION matology interfaces especially closely with the matology is closely related to the life sciences, in- study of other “spheres,” including the litho- cluding biophysics and human physiology. sphere, cryosphere, and biosphere, because water Applied climatology is very different in its ori- is present in all of these spheres. entation from the other subfields of climatology. Another subfield© Jones of &climatology Bartlett is Learning, dynamic cli- LLCWhile the others seek to uncover© Jones causes & Bartlettof various Learning, LLC matology, whichNOT is FOR primarily SALE concerned OR DISTRIBUTION with gen- aspects of climate, appliedNOT climatology FOR SALE is primar OR- DISTRIBUTION eral atmospheric dynamics—the processes that ily concerned with the effects of climate on other induce atmospheric motion. Most dynamic clima- natural and social phenomena. This subfield may tologists work at the planetary scale. This differs be further subdivided. One area of focus involves © Jonesfrom the & Bartlettsubfield ofLearning, synoptic climatology LLC , which attempts© to Jones improve & the Bartlett environment. Learning, Examples LLC is also concerned with the processes of circulation include using climatic data to create more efficient NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION but is more regionally focused and usually in- architectural and engineering design, generating volves more practical and specific applications improvements in medicine, and understanding than those described in the more theoretical area the impact of urban landscapes on the natural and of dynamic climatology. According to climatologist human environment. Other examples involve the © Jones & BartlettBrent Learning, Yarnal, synoptic LLC climatology “studies the© reJones- possibility & Bartlett of modifying Learning, the physical LLC atmosphere NOT FOR SALE lationshipsOR DISTRIBUTION between the atmospheric circulationNOT FORto suit SALE particular OR human DISTRIBUTION needs, such as with the

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Climatic Records and Statistics 7

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEpractice OR of DISTRIBUTIONcloud seeding, which attempts to ex- NOTmore FOR accurate SALE method OR because DISTRIBUTION we do not want to tract the maximum amount of precipitation from change the method of calculating the means in clouds in water-scarce regions. the middle of our long-term weather records. In general, each subfield overlaps with others. What would happen if the temperatures began to We cannot fully understand processes and im- rise abruptly at the same point in the period of re- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC pacts relevant to any subfield without touching on cord that the method of calculating the mean tem- aspects importantNOT for others FOR and SALE at least OR one DISTRIBUTION other perature changed? We would NOTnot know FOR whether SALE OR DISTRIBUTION nonclimatology field. For example, an agricultural the “change” represented an actual change in cli- climatologist interested in the effect of wind- mate or was just an artifact of a change in the breaks to reduce evaporation rates in an irrigated method of calculating the mean temperature. field© Jones must understand& Bartlett the Learning, near-surface LLC wind pro- But what about© Jones that average & Bartlett temperature? Learning, Is it LLC fileNOT and FOR turbulent SALE transfer OR DISTRIBUTIONof moisture, along with actually meaningful?NOT FOR Let’s SALEsay that ORyesterday DISTRIBUTION we soil and vegetation properties. recorded a high temperature of 32°C (90°F) and a low of 21°C (70°F). Our calculated average daily ■■Climatic Records and Statistics temperature would be about 27°C (80°F). This number would be used to simply describe and © Jones & BartlettBecause Learning,climatology LLCdeals with aggregates of © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOTrepresent FOR the SALE temperature OR DISTRIBUTION of the day for our loca- weather properties, statistics are used to reduce a tion. But the temperature was likely to have been vast array of recorded properties into one or a few 27°C (80°F) only during two very short periods in understandable numbers. For instance, we could the day, once during the mid-day hours when calculate the daily mean temperature—the aver- climbing toward the maximum and again as tem- age temperature for the entire day—for yesterday at © Jones & Bartlett Learning,peratures LLC decreased through the© Jones late afternoon. & Bartlett Learning, LLC a particular location through a number of methods. NOT FOR SALE OR DISTRIBUTIONSo the term “average temperature”NOT isFOR actually SALE a OR DISTRIBUTION First, we could take all recorded temperatures rather abstract notion. Most averages or climatic throughout the day, add them together, and then “normals” are abstract notions, but the advantage divide by the total number of observations. from a long-term (climatic) perspective is that they A much simpler (but less accurate) method of provide a “mechanism” for analyzing long-term calculating© Jones the& Bartlett daily mean Learning, temperature LLC is actu- © Jones & Bartlett Learning, LLC changes and variability. allyNOT the FOR one SALEthat is ORused: DISTRIBUTION A simple average is NOT FOR SALE OR DISTRIBUTION “Extremes” are somewhat different. As we saw calculated from the maximum and minimum earlier in this chapter, climatic extremes repre- temperatures recorded for the day. This method is sent the most unusual conditions recorded for a the most common because in the days before location. For example, these may represent the © Jones & Bartlettcomputers Learning, were used toLLC measure and record tem- © Jones & Bartlett Learning, LLC perature, special thermometers that operated on highest or lowest temperatures during a partic- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION the principle of a “bathtub ring” were able to leave ular time period. Extremes are often given on the a mark at the highest and lowest temperature ex- nightly news to give a reference point to the daily perienced since the last time that the thermome- recorded temperatures. We might hear that the ter was reset. Each day, human observers could high temperature for the day was 33°C (92°F), but determine the maximum© Jones and & minimum Bartlett temperLearning,- that LLC was still 5 C° (8 F°) lower© than Jones the “record& Bartlett Learning, LLC ature for the previousNOT 24 FOR hours, SALE but theyOR wouldDISTRIBUTION high” of 38°C (100°F) recorded onNOT the sameFOR date SALE in OR DISTRIBUTION not know any of the other temperatures that oc- 1963. As long as our recorded atmospheric proper- curred over that time span. For most of the period ties are within the extremes, we know that the at- of weather records, we knew only the maximum mosphere is operating within the expected range of conditions. When extremes are exceeded or and© Jones minimum & Bartlettdaily temperatures. Learning, LLC © Jones & Bartlett Learning, LLC Of course, the numerical average calculated by nearly exceeded, then the atmosphere may be con- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION the maximum–minimum method differs some- sidered to be behaving in an “anomalous” manner. what from the one obtained by taking all hourly The frequency with which extreme events occur is temperatures and dividing by 24. Even though we also important. Specifically, if extreme events oc- have automated systems now that can measure cur with increasing frequency, the environmental, © Jones & Bartlettand record Learning, temperatures LLC every second, we do not © agricultural,Jones & Bartlett epidemiological, Learning, and economicLLC im- NOT FOR SALEcalculate OR DISTRIBUTIONmean daily temperatures using this NOTpacts FOR will undoubtedly SALE OR increase. DISTRIBUTION

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8 Chapter 1 — Introduction to Climatology

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE ORWhy DISTRIBUTION are climatic records important? DuringNOT the FORmost weatherSALE ORrecords DISTRIBUTION for the world are confined to 1980s and 1990s the rather elementary notion that more-developed countries and tend to be collected climate changes over time was absorbed by the in, or near, population centers. Developing coun- general public. Before that time many people tries, rural areas, and especially the oceans are thought that climate remained static even though poorly represented in the global weather database, weather properties© Jones varied & considerablyBartlett Learning, around the LLC particularly in the earlier© part Jones of the & record Bartlett (Fig- Learning, LLC normals (averages).NOT FOR With SALEheightened OR understandDISTRIBUTION- ure 1.2). Oceans compriseNOT over FOR70 percent SALE of theOR DISTRIBUTION ing of weather processes came the realization that planet’s surface, yet relatively few long-term weather climate varies considerably as well. Climatic calcu- records exist for these locations. Most atmospheric lations and the representation of climate for a given recordings over oceans are collected from ships, © Jonesplace over & Bartlett time became Learning, exceedingly LLC important and and these© recordings Jones & are Bartlett biased by Learning, inconsistencies LLC NOTprecise. FOR TheSALE problems OR DISTRIBUTION associated with the calcula- in the heightNOT of FORthe ship-mounted SALE OR weather DISTRIBUTION station, tion of various atmospheric properties still existed, the type of station used, the time of observation, however, and the methods of calculating these and the composition of ship materials. Further- properties could have far-reaching implications on more, ocean surface temperatures are derived in a such endeavors as environmental planning, hazard variety of ways, from inserting a thermometer into a © Jones & Bartlettassessment, Learning, and governmentalLLC policy. © Jonesbucket & Bartlettof collected Learning, ocean water LLC to recording the NOT FOR SALE ORWith DISTRIBUTION today’s technology we would assumeNOT that FORtemperature SALE of OR water DISTRIBUTION passing through the bilge of calculating a simple average temperature for Earth, the ship (with the heat generated by the ship in- for instance, would be easy. However, data biases cluded in the recording). Vast tracts of ocean were and methodological differences complicate mat- largely ignored until the recent arrival of satellite ters. Many of these issues have been mathema monitoring and recording technology, because the tically corrected© Jones in recorded & Bartlett data. Learning, Given the LLC © Jones & Bartlett Learning, LLC representation of surface and atmospheric proper- corrections,NOT it is generally FOR SALE accepted OR that DISTRIBUTION Earth’s av- NOT FOR SALE OR DISTRIBUTION ties was greatly limited to shipping lanes. erage annual temperature has risen by about 0.4 C° Even records taken with rather sophisticated (0.7 F°) over the past century. weather stations may be biased and complicated to Another factor that complicates the interpreta- some degree by rather simple issues. Foremost tion of the observed warming is the increasingly © Jones & Bartlett Learning, LLC among these© Jones are station & Bartlett moves. Moving Learning, a station LLC urban location of many weather stations as urban NOT FOR SALE OR DISTRIBUTION even a fewNOT meters FOR may SALE ultimately OR DISTRIBUTIONbias long-term sprawl infringes on formerly rural weather sta- recordings as factors such as differing surface ma- tions. Early in the twentieth century many weather terials and solar exposure occur. Also of note is stations in the United States and elsewhere were time of observation bias, which involved data bias located on the fringe of major cities. This was es- based on the time of day when measurements are © Jones & Bartlettpecially Learning, true toward LLC the middle part of the ©cen Jones- & Bartlett Learning, LLC recorded at different stations. Finally, systematic NOT FOR SALE turyOR DISTRIBUTIONwith the construction of major airportsNOT far FOR SALE OR DISTRIBUTION from the urban core. Weather observations could biases and changes in the instrumentation may be recorded at the airport in a relatively rural, un- cause inaccuracies in measurements. The result of disturbed location. As cities grew, however, these these, and a host of other biases, is that consider- locations became swallowed up by urban areas. able data “correction” is required. Both the biases This instituted© Jones considerable & Bartlett bias into Learning, long-term LLC and the correction methods© fuel Jones debate & concerning Bartlett Learning, LLC records as NOTartificial FOR heat SALE from OR urban DISTRIBUTION sources, the occurrence of actual atmosNOTpheric FOR trends. SALE OR DISTRIBUTION known as the urban heat island, became part of the climatic record. Various properties, such as ■■Summary the abundance of concrete that absorbs solar en- © Jonesergy effectively, & Bartlett the Learning, absence of vegetation LLC and wa- This chapter© Jones introduces & Bartlett the field Learning, of climatology. LLC It NOTter FOR surfaces, SALE and OR the DISTRIBUTIONgeneration of waste heat by describesNOT the scopeFOR of SALE climatology, OR DISTRIBUTION the inherent human activities contribute to the heat island. The differences between meteorology and climatology, urban heat island provides an excellent example and the associated notions of weather and climate. of how humans can modify natural climates and Meteorology studies changes in weather, the state can complicate the calculation and analysis of of atmospheric properties for a given location over a © Jones & Bartlett“natural” Learning, climatic LLC changes. © Jonesrelatively & Bartlett short period Learning, of time, while LLC climatology ex- NOT FOR SALE ORIn DISTRIBUTION addition, the long-term recordings themselvesNOT FORamines SALE weather OR properties DISTRIBUTION over time for a location. may be plagued by other problems. Consider that Climatology is a holistic science in that it involves

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Summary 9

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Figure 1.2 Location of global surface observations at various years. Source: J. E. Hansen and S. Lebedeff, 1987, “Global trends of measured surface air temperature,” Journal of Geophysical Research, 92 D11, 13345–13372.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC understanding the interaction of the atmosphere sphere, hydrosphere, cryosphere, and biosphere. withNOT other FOR aspects SALE of the OR Earth–ocean–atmosphere DISTRIBUTION All are importantNOT to FORthe establishment SALE OR ofDISTRIBUTION global, system using many different spatial and temporal hemispheric, and regional climates. scales. Each scale partially defines the many Climatic data and calculations also are de- interlocking subfields of climatology, including scribed, with particular emphasis on climatic © Jones & Bartlettboundary-layer, Learning, physical, LLC hydro-, dynamic, synop- © normals,Jones &extremes, Bartlett and Learning, frequencies. LLC Some causes NOT FOR SALEtic, regional, OR DISTRIBUTION paleo-, bio-, and applied climatology. NOTof spurious FOR SALE climatic OR data, DISTRIBUTION such as the urban heat Interactions occur between the atmosphere, litho- island, are also introduced.

XXKey Terms

Agricultural climatology© Jones & BartlettFrequencies Learning, LLC Paleoclimatology© Jones & Bartlett Learning, LLC Applied climatologyNOT FOR SALEFriction OR DISTRIBUTION Physical climatologyNOT FOR SALE OR DISTRIBUTION Atmosphere Global hydrologic cycle Planetary scale Bioclimatology Human bioclimatology Pressure Biosphere Hydroclimatology Proxy evidence Boundary-layer© Jones & Bartlett Learning,Hydrosphere LLC © JonesRegional &climatology Bartlett Learning, LLC ClimateNOT FOR SALE OR DISTRIBUTIONLithosphere NOTSynoptic FOR climatology SALE OR DISTRIBUTION Climatology Local scale Synoptic scale Cloud seeding Mesoscale Time of observation bias Cryosphere Meteorology Urban heat island Daily mean temperature Microscale Varve © Jones & BartlettDynamic climatologyLearning, LLC Momentum © Jones & BartlettWeather Learning, LLC NOT FOR SALEEvaporation OR DISTRIBUTION National WeatherNOT Service FOR SALEWind OR DISTRIBUTION Extremes Normals 2ND PAGES

10 Chapter 1 — Introduction to Climatology

1. Why is the science of climatology inherently 1. Think of several examples of how advancements holistic? in science and technology may have helped cli- 2. Briefly ©describe Jones Earth’s & Bartlett “spheres.” Learning, Give exam- LLC matology to evolve as© a scienceJones since & Bartlett 1950. Learning, LLC ples of how each of the spheres is connected. 2. In today’s age of specialization, is climatology’s NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 3. Compare and contrast the notions of weather interdisciplinary nature an advantage or a dis- and climate. advantage? 4. Compare and contrast the sciences of meteo- 3. To what extent are “extreme events” a matter of rology and climatology. perspective? © Jones5. Describe & Bartlett the various Learning, spatial LLC and temporal 4. In what© Jones sense might & Bartlett the occurrence Learning, of non- LLC NOT FORscales SALE of climatology. OR DISTRIBUTION catastrophicNOT FOR events SALE cause ORcatastrophic DISTRIBUTION events 6. Discuss the different subdisciplines within to occur? climatology. How are they different from/ similar to one another? go.jblearning.com/Climatology3eCW © Jones & Bartlett7. Learning,How are mean LLC temperatures calculated?© Dis Jones- & Bartlett Learning, LLC cuss the problems inherent in the calculation Connect to this book’s website: go.jblearning.com/ NOT FOR SALE ORmethods. DISTRIBUTION NOT FORClimatology3eCW. SALE OR TheDISTRIBUTION site provides chapter 8. What is the urban heat island and why is it outlines, further readings, and other tools to help relevant to temperature assessment? you study for your class. You can also follow useful links for additional information on the topics © Jones & Bartlett Learning, LLCcovered in this chapter. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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