chapter 01 the earth's atmosphere
TRANSCRIPT
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The Earths Atmosphere
Chapter 1
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The Earth and its AtmosphereThe Earth and its Atmosphere
This chapter discusses:This chapter discusses:
1.1. Gases in Earth's atmosphereGases in Earth's atmosphere
2.2. Vertical structure of atmospheric pressureVertical structure of atmospheric pressure
& temperature& temperature
3.3. Types of weather & climate in theTypes of weather & climate in the
atmosphereatmosphere
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Solar Energy as RadiationSolar Energy as Radiation
Figure 1.1Figure 1.1
Nearly 150 million kilometers separate the sun and earth, yet solarNearly 150 million kilometers separate the sun and earth, yet solar
radiation drives earth's weather.radiation drives earth's weather.
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Earth's AtmosphereEarth's Atmosphere
99% of atmospheric gases, including water vapor, extend only 3099% of atmospheric gases, including water vapor, extend only 30
kilometer (km) above earth's surface.kilometer (km) above earth's surface.
Most of our weather, however, occurs within the first 10 to 15 km.Most of our weather, however, occurs within the first 10 to 15 km.
Figure 1.2Figure 1.2
Thin Gaseous envelope
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Composition of Atmosphere
Nitrogen - 78%
Oxygen - 21%
Water Vapor 0 to 4%
Carbon Dioxide - .037%
Other gases make up the rest
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Atmospheric GasesAtmospheric Gases
Nitrogen, oxygen,Nitrogen, oxygen,
argon, water vapor,argon, water vapor,
carbon dioxide, andcarbon dioxide, andmost other gasesmost other gases
are invisible.are invisible.
Clouds are not gas,
Clouds are not gas,but condensedbut condensed
vapor in the form ofvapor in the form of
liquid droplets.liquid droplets.
Ground basedGround basedsmog, which issmog, which is
visible, containsvisible, contains
reactants ofreactants of
nitrogen and ozone.nitrogen and ozone.
Ozone is the primary ingredient of smog!
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Variable & Increasing GasesVariable & Increasing Gases
Figure 1.3Figure 1.3
Nitrogen and oxygen concentrations experience little change,Nitrogen and oxygen concentrations experience little change,
but carbon dioxide, methane, nitrous oxides, andbut carbon dioxide, methane, nitrous oxides, and
chlorofluorocarbons are greenhouse gases experiencingchlorofluorocarbons are greenhouse gases experiencing
discernable increases in concentration. CO2 has risen morediscernable increases in concentration. CO2 has risen more
than 18% since 1958. Fossil fuels are the biggest problem!than 18% since 1958. Fossil fuels are the biggest problem!
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Atmospheric Greenhouse EffectAtmospheric Greenhouse Effect
The warming of the atmosphere by its
absorbing and emitting infrared
radiation while allowing shortwave
radiation to pass through. The gases
mainly responsible for the earths
atmospheric greenhouse effect are watervapor and carbon dioxide.
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Aerosols & PollutantsAerosols & Pollutants
Human andHuman andnatural activitiesnatural activities
displace tiny soil,displace tiny soil,
salt, and ashsalt, and ash
particles asparticles assuspendedsuspended
aerosols,aerosols,
as well as sulfuras well as sulfur
and nitrogenand nitrogenoxides, andoxides, and
hydrocarbons ashydrocarbons as
pollutants.pollutants.Figure 1.6Figure 1.6
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Pressure & DensityPressure & DensityGravity pulls gasesGravity pulls gases
toward earth'stoward earth's
surface, and thesurface, and thewhole column ofwhole column of
gases weighs 14.7gases weighs 14.7
psi at sea level, apsi at sea level, a
pressure of 1013.25pressure of 1013.25
mb or 29.92 in.Hg.mb or 29.92 in.Hg.
The amount of force
exerted Over an area of
surface is called
Air pressure!
Air Density is
The number of air
Molecules in a given
Space (volume)
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Vertical Pressure ProfileVertical Pressure Profile
Atmospheric pressureAtmospheric pressure
decreases rapidly withdecreases rapidly with
height. Climbing to anheight. Climbing to analtitude of only 5.5 kmaltitude of only 5.5 km
where the pressure iswhere the pressure is
500 mb, would put you500 mb, would put you
above oneabove one--half of thehalf of the
atmospheresatmospheres
molecules.molecules.
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Lapse Rate
The rate at which air temperature
decreases with height.
The standard (average) lapse rate in the
lower atmosphere is about 6.5C per 1
km or 3.6F per 1000 ft.
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Temperature Inversion An increase in air temperature with
height often called simply an inversion.
Radiosonde an instrument that
measures the vertical profile of air
temperature in the atmosphere
(sometimes exceeding 100,000 ft)
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AtmosphericLayersAtmosphericLayers
8 layers are defined by constant8 layers are defined by constant
trends in average airtrends in average airtemperature (which changestemperature (which changes
with pressure andwith pressure and
radiation), where the outerradiation), where the outer
exosphere is not shown.exosphere is not shown.
1.1. TroposphereTroposphere
2.2. TropopauseTropopause
3.3. StratosphereStratosphere
4.4. StratopauseStratopause5.5. MesosphereMesosphere
6.6. MesopauseMesopause
7.7. ThermosphereThermosphere
8.8. ExosphereExosphere
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AtmosphericLayersAtmosphericLayers
Figure 1.7Figure 1.7
Troposphere Temp decrease w/ height
Most of our weather occurs in this layer
Varies in height around the globe, but
Averages about 11 km in height.
Tropopause separates Troposphere from
Stratosphere. Generally higher in summer
Lower in winter.
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The troposphere is the lowest major atmospheric layer, and is located from the Earth'ssurface up to the bottom of the stratosphere. It has decreasing temperature with height (atan average rate of 3.5 F per thousand feet (6.5 C per kilometer); whereas the stratospherehas either constant or slowly increasing temperature with height. The troposphere is whereall of Earth's weather occurs. The boundary that divides the troposphere from thestratosphere is called the "tropopause", located at an altitude of around 5 miles in thewinter, to around 8 miles high in the summer, and as high as 11 or 12 miles in the deeptropics. When you see the top of a thunderstorm flatten out into an anvil cloud, like in theillustration above, it is usually because the updrafts in the storm are "bumping up against"
the bottom of the stratosphere
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AtmosphericLayersAtmosphericLayers
Figure 1.7Figure 1.7
Stratosphere
Temperature inversion in stratosphere
Ozone plays a major part in heating the air
At this altitude
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AtmosphericLayersAtmosphericLayers
Figure 1.7Figure 1.7
Mesosphere
Middle atmosphere Air thin, pressure low,
Need oxygen to live in this region. Air
quite Cold -90C (-130F) near the top of
mesosphere
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AtmosphericLayersAtmosphericLayers
Figure 1.7Figure 1.7
Thermosphere
Hot layer oxygen molecules absorb
energy from solar Rays warming the air.
Very few atoms and molecules in this
Region.
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The Stratosphere and Ozone Layer
Above the troposphere is the stratosphere, where air flow is mostly horizontal. The thin ozone layer in the upper
stratosphere has a high concentration of ozone, a particularly reactive form of oxygen. This layer is primarily responsible
for absorbing the ultraviolet radiation from the Sun. The formation of this layer is a delicate matter, since only when
oxygen is produced in the atmosphere can an ozone layer form and prevent an intense flux of ultraviolet radiation from
reaching the surface, where it is quite hazardous to the evolution of life. There is considerable recent concern that
manmade flourocarbon compounds may be depleting the ozone layer, with dire future consequences for life on the Earth.
The Mesosphere and Ionosphere
Above the stratosphere is the mesosphere and above that is the ionosphere (orthermosphere), where many atoms are
ionized (have gained or lost electrons so they have a net electrical charge). The ionosphere is very thin, but it is where
aurora take place, and is also responsible for absorbing the most energetic photons from the Sun, and for reflecting radio
waves, thereby making long-distance radio communication possible.
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Atmospheric Mixture & ChargeAtmospheric Mixture & Charge
Additional layersAdditional layers
include:include:
a) the homospherea) the homosphere
with 78% nitrogenwith 78% nitrogen
and 21% oxygenand 21% oxygen
b) the poorlyb) the poorly
mixedmixed
heterosphereheterosphere
c) the electricallyc) the electrically
chargedcharged
ionosphereionosphere
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Radio Wave PropagationRadio Wave Propagation
Figure 1.9 (Ionosphere Radio Prop)Figure 1.9 (Ionosphere Radio Prop)
AM radio waves are long enough to interfere with ions in the sunAM radio waves are long enough to interfere with ions in the sun--
charged D layer, but at night the D layer is weak and the AM signalcharged D layer, but at night the D layer is weak and the AM signal
propagates further, requiring stations to use less power.propagates further, requiring stations to use less power.
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Weather & ClimateWeather & Climate
Weather is comprised of theWeather is comprised of the
elements of:elements of:
a) air temperaturea) air temperature
b) air pressureb) air pressure
c) humidityc) humidity
d) cloudsd) clouds
e) precipitatione) precipitation
f) visibilityf) visibility
g) windg) wind
Climate represents longClimate represents long--termterm
(e.g. 30 yr) averages of weather.(e.g. 30 yr) averages of weather.
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Satellite InstrumentsSatellite Instruments
Meteorologists mayMeteorologists may
study larger weatherstudy larger weather
patterns with spacepatterns with space
borne instruments,borne instruments,
while groundwhile ground--basedbased
tools often measure atools often measure a
single point. (GOESsingle point. (GOESSAT)SAT)
Figure 1.10Figure 1.10
Meridians
Longitude
Latitude
Middle Latitudes 30-50N
Middle-latitude cyclonic stormHurricane
Thunderstorm
Tornado most violent disturbance in atms
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Surface Weather MapSurface Weather Map
Figure 1.11Figure 1.11
MeteorologistsMeteorologists
generate diagramsgenerate diagrams
of observedof observed
weather fromweather from
groundground--basedbasedinstruments.instruments.
This surface mapThis surface map
overlaps in timeoverlaps in time
with the previouswith the previous
satellite image.satellite image.
Low
High
Fronts
Wind Direction
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History of Meteorology Meteorology is the study of the atmosphere and its
phenomena
Aristotle wrote a book on natural philosophy (340 B
C)
entitled Meteorologica
Sum knowledge of weather/climate at time
Meteors were all things that fell from the sky or
were seen in the air
meteoros : Greek word meaning high in air
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History of Meteorology
Invention of weatherinstruments 1500s Galileo invented
water thermometer
1643 Torricelli inventedmercury barometer
1667 Hooke inventedanemometer
1719 Fahrenheit developedtemp scale based onboiling/freezing water
1735 Hadley explained howthe earths rotationinfluences winds in tropics
1742Celsius developed thecentigrade temp scale
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History of Meteorology 1787Charles discovered
relationship between temp and avolume of air
1835Coriolis used math to
demonstrate the effect that theearths rotation has on atmos.Motions
1869 first isobars were placed onmap
1920 concepts of air masses andweather fronts were formulatedin Norway
1940s upper air ballons/3-D viewof atmos
1950s high speed computers
1960 Tiros 1 first weathersatellite
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Impacts of Weather 1/5Impacts of Weather 1/5
Figure 1.12Figure 1.12
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Impacts of Weather 2/5Impacts of Weather 2/5
Figure 1.13Figure 1.13
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Impacts of Weather 3/5Impacts of Weather 3/5
Figure 1.14Figure 1.14
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Impacts of Weather 4/5Impacts of Weather 4/5
Figure 1.15Figure 1.15
146 people die each yearIn US from flash floods
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Impacts of Weather 5/5Impacts of Weather 5/5
Figure 1.16Figure 1.16
Lightning strikes earth
100 times every second
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