Meteorology, Climatology, and the Earth’s AtmosphereGlobal Environmental Change –

Lecture 2 Spring 2015

What is Meteorology?• One definition is the branch of science that deals with the atmosphere of a planet,

particularly that of the earth

• Data is analyzed and often plotted on maps to predict, or forecast, the weather for the next few hours to few days

• Long-range forecasts, which are more general and less accurate, may be made for a few months

• From the Greek, meteōron, of the atmosphere, and logia, study of

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Climatology• Refers to the study of the composite or generally prevailing

weather conditions of a region, as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds, throughout the year, averaged over a series of years

• Often means much longer, geologically significant, periods

• From the Greek klima, place or zone, and logia, study of

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Climatology Subcategories• Historical - the study of climate as related to human

history Focused only on the last few thousand years

• Paleoclimatology - seeks to reconstruct past climates by examining records such as ice cores and tree rings Tree-ring studies are known as dendroclimatology

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Climatology Indices• Climate indices based on several climate patterns are used to

characterize and understand the various climate mechanisms that culminate in our daily weather

• The climate patterns are based on modes of variability, with identifiable characteristics, specific regional effects, and, often. oscillatory behavior

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Examples of Climatology Indices• Antarctic oscillation (AAO)

• Arctic oscillation (AO)

• Atlantic multidecadal oscillation (AMO)

• El Niño Southern Oscillation (ENSO)

• Indian Ocean Dipole (IOD)

• Madden–Julian oscillation (MJO)

• North Atlantic oscillation (NAO)

• Pacific decadal oscillation (PDO)6

Video Clips• The Board of Atmospheric Sciences and

Climate of the National Research Council and National Academy of Sciences has produced a series of Short Videos called, “Climate Change – Lines of Evidence”

• Published July 2, 2012

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Chapter 1:What is Climate?

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Chapter 2: Is Earth Warming?

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America’s Climate Choices• In 2008, Congress requested the National Academies

to study climate change and report on their findings

• The National Academies responded by launching America's Climate Choices, a suite of studies designed to inform and guide responses to climate change across the nation

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America’s Climate Choices Video

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Earth’s Atmosphere• The atmosphere is complex

Layers and sub layers exist• Chemical differences exist between layers

• Change is continual Change results from uneven heating and

cooling, which results in atmospheric circulation

• The earth's atmosphere is a very thin layer wrapped around a large planet

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In this NASA photo, the troposphere is orange, the stratosphere is white, and the mesosphere is blue

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Atmospheric Layers• Atmospheric layers are denoted by words

ending in the suffix –sphere

• Boundaries are denoted by words ending in –pause

• Thermal properties are used in defining the atmospheric layers

Troposphere• Contains about 75% of the mass of the earth’s atmosphere

• Weather, major wind systems and clouds occur here

• Water vapor, dust, pollen, and soot particles are found here

• This layer is turbulent, with storms and atmospheric mixing

• The word troposphere comes from Greek tropos, meaning to turn or change, and Greek sphaira, meaning ball; perhaps best rendered as sphere of change First used in the early 20th century, perhaps coined by French

meteorologist Léon-Philippe Teisserenc de Bort (1855-1913)

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Tropopause• This layer represents an inflection point in a plot of temperature versus

altitude In the troposphere, temperature decreases with altitude At the tropopause, this changes, and temperature begins to increase with

altitude throughout the next highest layer

• Near the poles, the altitude of the tropopause is about 10 kilometers

• Near the equator, the altitude of the tropopause is about 18 kilometers

• The word tropopause comes from Greek tropos, meaning to turn or change, and English pause, meaning discontinuance

• The temperature at the tropopause is around - 60°C

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Stratosphere• The “ozone layer” is found in the stratosphere

• Contains about 24% of the mass of the earth’s atmosphere

• The word stratosphere comes from Latin stratus, meaning “a spreading out”, and Greek sphaira, meaning ball; perhaps best rendered as sphere of layers

First used in the early 20th century, coined by French meteorologist Léon-Philippe Teisserenc de Bort (1855-1913)

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Stratospheric Layering• It is stratified in temperature, with warmer layers higher up

and cooler layers farther down

• This vertical stratification, with warmer layers above and cooler layers below, makes the stratosphere dynamically stable There is no regular convection and associated turbulence in this part of

the atmosphere.

• The stratosphere begins at the tropopause and extends upward about 50 kilometers

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Flying in the Stratosphere• Jets fly in this layer to reduce fuel consumption

Commercial airliners typically cruise at altitudes of 9–12 kilometers in temperate latitudes, which is in the lower reaches of the stratosphere

When the Concorde was flying, it would cruise at mach 2 at about 18 kilometers

The SR-71 would cruise at mach 3 at 26 kilometers (The SR-71 is a later version of the U-2 spy plane, used for atmospheric research)

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Stratopause• Marks the boundary between the stratosphere and the

mesosphere

• Like the tropopause, this layer represents an inflection point in a plot of temperature versus altitude In the stratosphere, temperature is nearly constant for a while,

increasing very slowly with altitude Then it begins to increase quickly, reaching a maximum of around 0°C

at the stratopause In the mesosphere, temperature begins to decrease again

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Mesosphere• This layer ranges in altitude from 50 to 85 kilometers

above the earth• The word mesosphere comes from Greek mesos,

meaning middle, and Greek sphaira, meaning ball

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Mesopause• Marks the boundary between the mesosphere and the

thermosphere

• The temperature at 85 kilometers above the earth ranges from - 80°C to - 120°C

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Thermosphere• Above about 85 kilometers, the temperature begins to

increase again• At roughly 100 kilometers altitude, we have a

boundary sometimes called the turbopause• Below the turbopause, turbulent mixing keeps the

gases well-mixed• Above the turbopause, residual atmospheric gases

sort into strata according to molecular mass

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Ionosphere• Superimposed on the thermosphere is a layer called the ionosphere, which

ranges from about 85 kilometers to 600 kilometers above the earth

• Within this layer, absorption of strong solar ultraviolet radiation causes gases to ionize, which makes the layer electrically conductive

• Ionized atmospheric gases refract high frequency (HF, or shortwave) radio waves

• Because of this property, the ionosphere can be utilized to bounce a transmitted signal down to ground

• Transcontinental HF-connections may involve up to 5 bounces

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Geomagnetic Storms• A temporary, intense disturbance of the Earth's magnetosphere by solar flares

• During a geomagnetic storm the F2 layer will become unstable, fragment, and may even disappear completely

• In the Northern and Southern pole regions of the Earth aurorae will be observable in the sky Energy from the sun acts on electrons in the magnetosphere which, energized

and accelerated by the solar wind, bombard oxygen molecules in the upper atmosphere, causing them to luminesce

Often, storms and other events on the surface of the sun trigger a burst of auroral activity

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Aurora Borealis

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February 11, 2004