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Chapter 1—Introduction to ClimatologyMeteorology and ClimatologyScales in ClimatologySubfields of ClimatologyClimatic Records and StatisticsSummary

Chapter 2—Introduction to the AtmosphereOrigin of the Earth and AtmosphereAtmospheric CompositionThe Carbon CycleThe Faint Young Sun ParadoxSummary

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Introduction to Climatology1CHAPTERChapter at a GlanceMeteorology and ClimatologyScales in ClimatologySubfields of ClimatologyClimatic Records and StatisticsSummaryReview

Climatology may be described as the scientificstudy of climate and the behavior of the atmos-

phere—the thin gaseous layer surrounding theearth’s surface—integrated over time. While thisdefinition is certainly acceptable, it fails to cap-ture fully the scope of climatology. Climatologyis a holistic science that incorporates theories,ideas, and data from all parts of the earth-ocean-atmosphere system, including those in-fluenced by humans, into an integrated wholeto explain atmospheric properties.

The earth-ocean-atmosphere system may bedivided into a number of zones, with each tradi-tionally studied by a separate scientific disci-pline. The part of the solid earth nearest to thesurface (to a depth of perhaps 100 km) is calledthe lithosphere and is studied by geologists,geophysicists, geomorphologists, soil scientists,vulcanologists, and other practitioners of theenvironmental and agricultural sciences. Thepart of the system that is covered by liquid wa-ter is termed the hydrosphere; it is consideredby those in the fields of oceanography, hydrolo-gy, and limnology (the study of lakes). The re-gion comprised of frozen water in all its forms(glaciers, sea ice, surface and subsurface ice,and snow) is known as the cryosphere and isstudied by those specializing in glaciology, as

well as specialized physical geographers, geolo-gists, and oceanographers. The biosphere,which crosscuts the lithosphere, hydrosphere,cryosphere, and atmosphere, includes the zonecontaining all life forms on the planet, includ-ing humans. The biosphere is examined by spe-cialists in the wide array of life sciences, alongwith physical geographers, geologists, and otherenvironmental scientists.

The atmosphere is the component of the sys-tem studied by climatologists and meteorologists.Holistic interactions between the atmosphereand each combination of the “spheres” are impor-tant contributors to the climate (Table 1.1), atscales from local to planetary. Thus, climatolo-gists must draw upon knowledge generated inseveral natural and sometimes social scientificdisciplines to understand the processes at work inthe atmosphere. Because of its holistic nature ofatmospheric properties over time and space, cli-matology naturally falls into the broader disci-pline of geography.

Over the course of this book, we shall see thatthese processes can be complex. The effects ofsome of these interactions cascade up from localto planetary scales, and effects of others tend tocascade down the various scales to ultimately af-fect individual locations over time. The process-es are so interrelated with other spheres andwith other scales that it is often difficult to gen-eralize by saying that any particular impact be-gins at one component of the system or side ofthe scale and proceeds to another.

We can state that the scope of climatology isbroad. It has also expanded widely from itsroots in ancient Greece. The term “climatology”is derived from the Greek term klima, whichmeans “slope” and reflects the early idea that

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Table 1.1 Examples of Interactions Between the Atmosphere and the Other “Spheres,” and Impacts on ThermalReceipt/Climate

Sphere Interacting with Atmosphere Example of a Potential Impact

Lithosphere Large volcanic eruptions can create a dust and soot cloud that can reduce thereceipt of solar radiation, cooling the global atmosphere for months or years.

Hydrosphere Changes in ocean circulation can cause global atmospheric circulation shifts thatproduce warming in some regions.

Cryosphere Melting of polar ice caps can cause extra heating at the surface where ice waslocated because bare ground reflects less of the solar energy incident upon thesurface than ice.

Biosphere Deforestation increases the amount of solar energy received at the surface.

distance from the equator alone (which causesdifferences in the angle or slope of the sun inthe sky) drove climate. The second part of theword is derived from logos, defined as “study,”or “discourse.” Modern climatology seeks notonly to describe the nature of the atmospherefrom location to location over many differenttime scales but also to explain why particularattributes occur and change over time, and toassess the potential impacts of those changeson natural and social systems.

■ Meteorology and Climatology

The two atmospheric sciences, meteorology andclimatology, are inherently linked. Meteorology

is the study of weather—the overall instanta-neous condition of the atmosphere at a certainplace and time. Weather is described throughthe direct measurement of particular atmos-pheric properties such as temperature, precipi-tation, humidity, wind direction, wind speed,cloud cover, and cloud type. The term “weather”refers to tangible aspects of the atmosphere. Aquick look or walk outside may be all that isneeded to describe the weather of your location.Of course, these observations may be comparedwith the state of the atmosphere at other loca-tions, which in most cases will be different.

Because meteorology deals with direct andspecific measurements of atmospheric proper-ties, discussion of weather centers on short-duration time intervals. Weather is generallydiscussed over time spans of a few days at most.How is the weather today? How does this com-pare with the weather we had yesterday? Whatwill the weather here be like tomorrow or to-

4 C H A P T E R 1 — Introduction to Climatology

ward the end of the week? All of these questionsinvolve short-term analysis of atmosphericproperties for a given time and place. So mete-orology involves only the present, the immedi-ate past, and the very near future.

But a much more important component ofmeteorology is the examination of the forcesthat create the atmospheric properties beingmeasured. Changes in the magnitude or direc-tion of these forces over time, and changes inthe internal properties of the matter being af-fected by these forces, create differences inweather conditions over time. Although manymeteorologists are not directly involved withforecasting these changes, meteorology is theonly science in which a primary goal is to pre-dict future conditions. Weather forecasting hasimproved greatly with recent technological en-hancements that allow for improved under-standing of these forces, along with improvedobservation, data collection, and modeling ofthe atmosphere. Currently, weather forecastsproduced by the National Weather Service in theUnited States are accurate for most locationsover a period of approximately 72 hours.

By contrast, climate refers to the state of theatmosphere for a given place over time. It is im-portant to note that climatologists are indeedconcerned with the same atmospheric process-es that meteorologists study, but the scope isdifferent. Meteorologists may study theprocesses for their own sake, while climatolo-gists study the processes in order to understandthe long-term consequences of those processes.Therefore, climatology allows us to study at-mospheric processes and their impacts far be-yond present-day weather.

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5Meteorology and Climatology

There are three properties of the climate toconsider: normals, extremes, and frequencies.These are used to gauge the state of the atmos-phere over a particular time period as comparedwith atmospheric conditions at a similar time pe-riod in the past. Normals refer to average weatherconditions at a place. Climatic normals are typi-cally calculated for 30-year periods and give aview of the type of expected weather conditionsfor a location through the course of a year. For ex-ample, climatologically normal conditions inCrestview, Florida, are hot and humid during thesummer and cool but not cold in winter.

Two places could have the same average con-ditions but with different ranges of those condi-tions, in the same way that two students whoboth have an average of 85 percent in a classmay not have acquired that average by earningthe same score on each graded assignment.Therefore, extremes are used to describe themaximum and minimum measurements of at-mospheric variables that can be expected to oc-cur at a certain place and time, based on a longperiod of observations. For example, a tempera-ture of 0�C (32�F) at Crestview in April would falloutside of the range of expected temperatures.

Finally, frequencies refer to the rate of inci-dence of a particular phenomenon at a particu-lar place, over a long period of time. Frequencydata are often important for risk assessment,engineering, or agricultural applications. Forinstance, the frequency of hailstorms in a citywill be a factor in determining a homeowner’sinsurance premium. Or if an engineer designs aculvert to accommodate 8 cm (3 in.) of rain in a5-hour period but that frequency is exceeded anaverage of five times per year, this rate of failuremay or may not be acceptable to the citizens af-fected by the culvert. A farmer may want toknow how many days on average have morethan 1.5 cm (0.6 in.) of rain in October becauseOctober rains will be problematic for any cropthat is to be harvested during that month.

We can say then that both meteorologists andclimatologists study the same atmosphericprocesses, but with three primary and impor-tant differences. First, the time scales involvedare different. Meteorologists are primarily con-cerned with features of the atmosphere at a par-ticular time and place—the “weather”—whileclimatologists study the long-term patterns and

trends of those short-term features—the “cli-mate.” Second, meteorologists are more con-cerned with the processes for their own sake,while climatologists consider the long-term im-plications of those processes. Third, climatologyis inherently more intertwined with processeshappening not just in the atmosphere but also inthe other “spheres” because the interactions be-tween the atmosphere and the other spheres ismore likely to have important consequencesover longer, rather than shorter, time scales. Thisis particularly true if those processes occur overlarge areas, because the impacts will usually takelonger to develop in such cases. For instance, ifthe Great Lakes were to totally evaporate, such aprocess would necessarily take place over a longtime period. The difference in water level in theGreat Lakes between today and tomorrow wouldnot cause much impact on tomorrow’s weatheras compared with today’s. Therefore, a meteor-ologist would not really need to take this atmos-phere-hydrosphere interaction into accountwhen considering tomorrow’s weather. Howev-er, the difference in water content between theGreat Lakes over centuries would be more likelyto have a noticeable and dramatic impact on cli-mate during that time period. Therefore, inter-actions between the atmosphere and otherspheres, such as in this example, must be con-sidered when evaluating climate.

Regardless of the differences between meteor-ology and climatology, it is important to recognizethat the distinction between the two is becomingincreasingly blurred over time. A successful clima-tologist should have a firm grounding in the lawsof atmospheric physics and chemistry that dictatethe instantaneous behavior of the atmosphere. Aneffective meteorologist should recognize the im-portance of patterns over time and the impacts ofthose patterns, and the influence of other compo-nents of the earth-ocean-atmosphere system.

The holistic perspective of climatology alsocarries over to include interactions between theatmosphere and social systems. The impact ofpeople on their environment is a theme in cli-matology that is becoming more prevalent inrecent years. It is being increasingly recognizedthat many features of the human condition arerelated to climate. This is especially true of cli-matic “extremes” and “frequencies,” because itis the “abnormal” conditions, and conditions

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100

108107106105104103

Spatial Scale (meters)

Tem

po

ral S

cale

(sec

on

ds)

102101100

Atmospheric planetary waves

Midlatitude cycloneHurricane

Land/sea breeze

ThunderstormTornado

Dust devil

Turbulence in an urban city street

Microturbulence

10–110–2

106

105

104

103

102

101

Micro PlanetarySynopticMesoLocal

Figure 1.1 Spatial-temporal relationships for selected atmospheric features.

exceeding certain thresholds, that generallycause the greatest impact on individuals andsociety.

■ Scales in Climatology

We have already mentioned the importance oftemporal scale in climatology. It is also importantto emphasize that climatology involves the studyof atmospheric phenomena along many differ-ent spatial scales. There is usually a direct rela-tionship between the size of individualatmospheric phenomena and the time scale inwhich that phenomenon occurs (Figure 1.1). Themicroscale represents the smallest of all atmos-pheric scales. Phenomena that operate along thisspatial scale are smaller than 0.5 km (0.3 mi) andtypically last from a few seconds to a few hours. Atiny circulation between the underside and thetop of an individual leaf falls into this category, asdoes a tornado funnel cloud, and everything be-tween. A larger scale is the local scale, which op-erates over areas between about 0.5 and 5 km(0.3 to 3 mi)—about the size of a small town. Atypical thunderstorm falls into this spatial scale.

The next spatial scale is the mesoscale, whichinvolves systems that operate over areas betweenabout 5 and 100 km (3 to 60 mi) and typically lastfrom a few hours to a few days. Such systems in-clude those that you may have encountered inearlier coursework, such as the mountain/valleybreeze and land/sea breeze circulation systems,clusters of interacting thunderstorms known asmesoscale convective complexes (MCCs), a re-

lated phenomenon associated with cold frontstermed mesoscale convective systems (MCSs),and the central region of a hurricane.

Moving toward larger phenomena, we cometo the synoptic scale, a spatial scale of analysisthat functions over areas between 100 and10,000 km (60 to 6000 mi). Systems of this sizetypically operate over periods of days to weeks.Entire tropical cyclone systems and midlatitude(frontal) cyclones with their trailing fronts fall in-to the synoptic scale. Because these phenomenaare quite frequent and directly affect many peo-ple, the synoptic scale is perhaps the most stud-ied spatial scale in the atmospheric sciences.

Finally, we can also study and view climateover an entire hemisphere or even the entireglobe. This represents the largest spatial scalepossible and is termed the planetary scale, as itencompasses atmospheric phenomena on theorder of 10,000 to 40,000 km (6000 to 24,000 mi).Because in general, the largest spatial systemsoperate over the longest time scales, it is no sur-prise then that planetary-scale systems operateover temporal scales that span weeks tomonths. Examples of planetary-scale systemsinclude the broad wavelike flow in the upper at-mosphere, and the major latitudinal pressure

and wind belts that encircle the planet.

■ Subfields of Climatology

Climatology can be divided into several sub-fields, some of which correspond to certainscales of analysis. For instance, the study of the

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7Subfields of Climatology

microscale processes involving interactions be-tween the lower atmosphere and the local sur-face falls into the realm of boundary-layer

climatology. This subfield is primarily concernedwith exchanges in energy, mass, and momentumnear the surface. Physical processes can becomevery complex in the near-surface “boundary lay-er” for two reasons. First, the decreasing effect offriction from the surface upward complicates themotion of the atmosphere and involves signifi-cant transfer of momentum downward to thesurface. Second, the most vigorous exchanges ofenergy and moisture occur in this layer becausesolar radiant energy striking the ground warms itgreatly and rapidly compared to the atmosphereabove it, and because the source of water forevaporation is at the surface. Boundary-layer cli-matology may be further subdivided into topicsthat examine surface-atmosphere interactions inmountain/alpine regions, urban landscapes, andvarious vegetated land covers, and even as partof larger-scale weather/climate phenomena.

Physical climatology is related to boundary-layer climatology in that it studies energy andmatter. However, it differs in that it emphasizesthe nature of atmospheric energy and matterthemselves at climatic time scales, rather thanthe processes involving energy, mass, and mo-mentum exchanges only in the near-surface at-mosphere. Some examples would includestudies on the causes of lightning, atmosphericoptical effects, microphysics of cloud formation,atmospheric chemistry, and air pollution. Whilemeteorology has traditionally emphasized thistype of work to a greater extent than climatol-ogy, climatologists have contributed to our un-derstanding of these phenomena. Furthermore,the convergence of meteorology and climatol-ogy as disciplines will likely lead to more overlapin these topics of research in the future.

Hydroclimatology involves the processes (at allspacial scales) of interaction between the atmos-phere and near-surface water in all of its forms.This subfield analyzes all components of the glob-

al hydrologic cycle. Hydroclimatology interfacesespecially closely with the study of other“spheres,” including the lithosphere, cryosphere,and biosphere, because water is present in all ofthese spheres.

Another subfield of climatology is dynamic

climatology, which is primarily concerned with

general atmospheric dynamics—the processesthat induce atmospheric motion. Most dynamicclimatologists work at the planetary scale. Thisdiffers from the subfield of synoptic climatol-

ogy, which is also concerned with the processesof circulation but is more regionally focusedand usually involves more practical and specificapplications than those described in the moretheoretical area of dynamic climatology. Ac-cording to climatologist Brent Yarnal, synopticclimatology “studies the relationships betweenthe atmospheric circulation and the surface en-vironment of a region.” He goes on to state that,“because synoptic climatology seeks to explainkey interactions between the atmosphere andsurface environment, it has great potential forbasic and applied research in the environmen-tal sciences.” Synoptic climatology may act as akeystone that links studies of atmospheric dy-namics with applications in various other disci-plines.

Synoptic climatology is similar in some waysto regional climatology, a description of the cli-mate of a particular region of the surface. How-ever, synoptic climatology necessarily involvesthe explanation of process, while regional cli-matology does not. Some view regional clima-tology simply as a broader version of synopticclimatology.

The study of climate may extend to times be-fore the advent of the instrumental weatherrecord. This subfield of climatology is termedpaleoclimatology and involves the extraction ofclimatic data from indirect sources. This proxy

evidence may include human sources such asbooks, journals, diaries, newspapers, and art-work to gain information about pre-instrumental climates. However, the fieldprimarily focuses on biological, geological, geo-chemical, and geophysical proxy sources, suchas the analysis of tree rings, fossils, corals,pollen, ice cores, striations in rocks, andvarves—sediment deposited annually on thebottoms of lakes that freeze in winter.

Bioclimatology is a very diverse subfield thatincludes the interaction of living things withtheir atmospheric environment. Agricultural cli-

matology is the branch of bioclimatology thatdeals with the impact of atmospheric propertiesand processes on living things of economic val-ue. Human bioclimatology is closely related to

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the life sciences, including biophysics and hu-man physiology.

Applied climatology is very different in itsorientation from the other subfields of climatol-ogy. While the others seek to uncover causes ofvarious aspects of climate, applied climatologyis primarily concerned with the effects of cli-mate on other natural and social phenomena.This subfield may be further divided into anumber of fields. One area of focus involves uti-lizing our knowledge of climate to improve theenvironment. Examples include using climaticdata to create more efficient architectural andengineering design, generating improvementsin medicine, and understanding the impact ofurban landscapes on the natural and humanenvironment. Another realm involves the possi-bility of modifying the physical atmosphere tosuit particular human needs. One example in-cludes the practice of cloud seeding to extractthe maximum amount of precipitation fromclouds in water-scarce regions.

In general, each subfield overlaps with oth-ers. We cannot fully understand processes andimpacts relevant to any subfield without touch-ing on aspects important for others and at leastone other nonclimatology field. For example, anagricultural climatologist interested in the effectof windbreaks on evaporation rates in an irrigat-ed field must understand the near-surface windprofile and turbulent transfer of moisture, alongwith soil and vegetation properties. Once againwe see that climatology is a holistic science.

■ Climatic Records and Statistics

Because climatology deals with aggregates ofweather properties, statistics are used to re-duce a vast array of recorded properties intoone or a few understandable numbers. For in-stance, we could calculate the daily mean

temperature—the average temperature forthe entire day—for yesterday at a placethrough a number of methods. First, we couldtake all recorded temperatures throughoutthe day, add them together, and then divideby the total number of observations. As an ex-ample, we could take all hourly recordings of


temperature, sum them, and divide by 24.This would yield an “average” temperature forthe day.

A much simpler (but less accurate) methodof calculating the daily mean temperature is ac-tually the one that is used: A simple average iscalculated for the maximum and minimumtemperatures recorded for the day. This methodis the one most commonly employed because inthe days before computers were used to meas-ure and record temperature, special thermome-ters that operated on the principle of a “bathtubring” were able to leave a mark at the highestand lowest temperature experienced since thelast time that the thermometer was reset. Eachday, human observers would be able to deter-mine the maximum and minimum temperaturefor the previous 24 hours, but they would notknow any of the other temperatures that oc-curred over that time span. Thus, for most of theperiod of weather records, we knew only themaximum and minimum daily temperatures.

Of course, the numerical average calculatedby the maximum-minimum method will differsomewhat from the one obtained by taking allhourly temperatures and dividing by 24. Eventhough we have computers now that can meas-ure and record temperatures every second, wedo not calculate mean daily temperatures usingthis more accurate method because we do notwant to change the method of calculating themeans in the middle of our long-term weatherrecords. What would happen if the tempera-tures began to rise abruptly at the same pointin the period of record that the method of cal-culating the mean temperature changed? Wewould not be able to know whether the“change” represented an actual change in cli-mate or was just an artifact of a change in themethod of calculating the mean temperature.

But what about that average temperature? Isit actually meaningful? Let’s say that yesterdaywe recorded a high temperature of 32�C (90�F)and a low of 21�C (70�F). Our calculated averagedaily temperature would be about 27�C (80�F).This number would be used to simply describeand represent the temperature of the day forour location. But the temperature was likely tohave been 27�C (80�F) only during two very

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9Climatic Records and Statistics

short periods in the day, once during the after-noon when climbing toward the maximum, andagain as temperatures decreased through thelate afternoon. So the term “average tempera-ture” is actually a rather abstract notion. Mostaverages or climatic “normals” are abstract no-tions, but the advantage from a long-term (cli-matic) perspective is that they provide a“mechanism” for analyzing long-term changesand variability.

“Extremes” are somewhat different. As we sawearlier in this chapter, climatic extremes repre-sent the most unusual conditions recorded for alocation. For example, these may represent thehighest or lowest temperatures recorded duringa particular time period. Extremes are often giv-en on the nightly news to give a reference pointto the daily recorded temperatures. We mighthear that the high temperature for the day was33�C (92�F) but that was still 5 C� (8 F�) lower thanthe “record high” of 38�C (100�F) recorded on thesame date in 1963. As long as our recorded at-mospheric properties are within the extremes,we know that the atmosphere is operating withinthe expected range of conditions. When ex-tremes are exceeded or nearly exceeded, then theatmosphere may be considered to be behavingin an “anomalous” manner. The frequency withwhich extreme events occur is also important.Specifically, if extreme events occur with increas-ing frequency, the environmental, agricultural,epidemiological, and economic impacts will un-doubtedly increase.

Why are climatic records important? Duringthe 1980s and 1990s, the rather elementary no-tion that climate changes over time was ab-sorbed by the general public. Before that time,many people thought that climate remainedstatic even though weather properties variedconsiderably around the normals (averages).With heightened understanding of weatherprocesses came the realization that climate var-ied considerably as well. Climatic calculationsand the representation of climate for a givenplace over time became exceedingly importantand precise. However, the problems associatedwith the calculation of various atmosphericproperties still existed, and the methods of cal-culation of these properties could have far-

reaching implications on such endeavors as en-vironmental planning, hazard assessment, andgovernmental policy.

With today’s technology we would assumethat calculating a simple average temperaturefor earth, for instance, would be easy. However,data biases and methodological differencescomplicate matters. It is generally accepted thatthe earth’s average annual temperature hasrisen by about 0.4 C� (0.7 F�) over the past cen-tury. Until recently, many did not accept thatthis temperature increase was correct becauseof many perceived data biases, such as changesto instrumentation, especially associated withearly twentieth century recordings.

Another factor that complicated the interpre-tation of the observed warming was the increas-ingly urban location of many weather stations asurban sprawl infringed on formerly rural weatherstations. Early in the twentieth century, manyweather stations in the United States and else-where were located on the fringe of major cities.This was especially true toward the middle part ofthe century with the construction of major air-ports far from the urban core. Weather observa-tions could be recorded at the airport in arelatively rural, undisturbed location. As citiesgrew, however, these locations became swallowedup by urban areas. This instituted considerablebias into long-term records as artificial heat fromurban sources, known as the urban heat island,became part of the climatic record. While the ur-ban heat island is discussed in more detail inChapter 12, we can say for now that various prop-erties, such as the abundance of concrete that ab-sorbs solar energy effectively, the absence ofvegetation and water surfaces, and the genera-tion of waste heat by human activities contributeto the heat island. The urban heat island providesan excellent example of how humans can modifynatural climates and can complicate the calcula-tion and analysis of “natural” climatic changes.

In addition, the long-term recordings them-selves may be plagued by other problems. Con-sider that most weather records for the worldare confined to more-developed countries andtend to be collected in, or near, population cen-ters. Developing countries, rural areas, and es-pecially the oceans are poorly represented in

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Figure 1.2 Location of global surface observations at various years. Source: J.E. Hansen and S. Lebedeff, 1987. Globaltrends of measured surface air temperature. Journal of Geophysical Research 92D11, 13345–13372.

the global weather database, particularly in theearlier part of the record (Figure 1.2). Oceanscomprise over 70 percent of the planet’s surface,yet relatively few long-term weather records existfor these locations. Most atmospheric recordingsover oceans are collected from ships, and theserecordings are biased by inconsistencies in theheight of the ship-mounted weather station, thetype of station used, the time of observation, andthe composition of ship materials. Furthermore,ocean surface temperatures are derived in a vari-ety of ways, from pulling up a bucket of oceanwater and inserting a thermometer to recordingthe temperature of water passing through thebilge of the ship (with the heat of the ship includ-ed in the recording). Vast tracts of ocean werelargely ignored until the recent arrival of satellitemonitoring and recording technology, as the rep-resentation of surface and atmospheric proper-ties were greatly limited to shipping lanes.

Even records taken with rather sophisticatedweather stations may be biased and complicat-


ed to some degree by rather simple issues. Fore-most among these are station moves. Moving astation even a few meters may ultimately biaslong-term recordings as factors such as differ-ing surface materials and solar exposure occur.Also of note is a differing time in the day atwhich measurements were taken at differentstations. And finally, systematic biases andchanges in the instrumentation may cause in-accuracies in measurements. The result ofthese, and a host of other biases, is that consid-erable data “correction” is required. Both the bi-ases and the correction methods fuel debateconcerning the occurrence of actual atmos-pheric trends.

■ Summary

This chapter introduced the field of climatol-ogy. It described the scope of climatology, theinherent differences between meteorology and

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11Review

climatology, and the associated notions ofweather and climate. Meteorology studieschanges in weather, the state of atmosphericproperties for a given location, while climatol-ogy examines weather properties over time fora location. Climatology is a holistic science inthat it involves understanding the interaction ofthe atmosphere with other aspects of the earth-ocean-atmosphere system using many differentspatial and temporal scales. Each scale partiallydefines the many interlocking subfields of cli-matology, including boundary-layer, physical,

hydro-, dynamic, synoptic, regional, paleo-,bio-, and applied climatology. Interactions oc-cur between the atmosphere, lithosphere, hy-drosphere, cryosphere, and biosphere. All areimportant to the establishment of global, hemi-spheric, and regional climates.

Climatic data and calculations also were dis-cussed, with particular emphasis on climaticnormals, extremes, and frequencies. Somecauses of spurious climatic data, such as the ur-ban heat island, were also introduced.

Review

� Key Terms

Agricultural climatology

Applied climatology

Atmosphere

Bioclimatology

Biosphere

Boundary-layer climatology

Climate

Climatology

Cloud seeding

Cryosphere

Daily mean temperature

Dynamic climatology

Evaporation

Extremes

Frequencies

Friction

Global hydrologic cycle

Human bioclimatology

Hydroclimatology

Hydrosphere

Lithosphere

Local scale

Mesoscale

Meteorology

Microscale

Momentum

National Weather Service

Normals

Paleoclimatology

Physical climatology

Planetary scale

Pressure

Proxy evidence

Regional climatology

Synoptic climatology

Synoptic scale

Urban heat island

Varve

Weather

Wind

� Review Questions

1. Why is the science of climatology inherentlyholistic?

2. Briefly describe earth’s “spheres.” Giveexamples of how each of the spheres isconnected.

3. Compare and contrast the notions ofweather and climate.

4. Compare and contrast the sciences of mete-orology and climatology.

5. Describe the various spatial and temporalscales of climatology.

6. Discuss the different sub-disciplines withinclimatology. How are they differentfrom/similar to one another?

7. How are mean temperatures calculated?Discuss the problems inherent in the calcu-lation methods.

8. What is the urban heat island and why is itrelevant to temperature assessment?

� Questions for Thought

1. Think of several examples of how advance-ments in science and technology may havehelped climatology to evolve as a sciencesince 1950.

2. In today’s age of specialization, is climatol-ogy’s interdisciplinary nature an advantageor a disadvantage?

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http://physicalscience.jbpub.com/book/climatology

Connect to this book’s website:

http://physicalscience.jbpub.com/book/

climatology. The site provides chapter outlines and

other tools to help you study for your class. You can

also follow useful links for additional information

on the topics covered in this chapter.

� Further Reading

Brazdil, R., C. Pfister, H. Wanner, H. Von Storch, and J.Luterbacher. 2005. Historical climatology inEurope—The state of the art. Climatic Change70(3), 363–430.

Oliver, J. E. 1977. The applicability of “climatology forgeographers.” Annals of the Association of Ameri-can Geographers 67(1), 175–76.

Terjung, W. H. 1976. Climatology for geographers.Annals of the Association of American Geographers66(2), 199–222.

––1977. Comment in reply. Annals of the Associationof American Geographers 67(1), 176–77.

Yarnal, B. 1993. Synoptic Climatology in Environ-mental Analysis: A Primer. Belhaven Press.

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