chapter 01 the earth's atmosphere

8/8/2019 Chapter 01 the Earth's Atmosphere

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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.


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


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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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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Stratosphere

Temperature inversion in stratosphere

Ozone plays a major part in heating the air

At this altitude


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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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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)


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


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



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146 people die each yearIn US from flash floods


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Lightning strikes earth

100 times every second


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chapter 01 the earth's atmosphere

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