lecture 7 earth as a planet

8/7/2019 Lecture 7 Earth as a planet

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Earth as a PlanetEarth as a Planet

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Lecture 7Lecture 7

Dr. Norizan Ahmad, IP Teknik, Kuala Lumpur


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Earth:Earth:

Earth as a planetEarth as a planet

The atmosphereThe atmosphere

CloudsClouds Air pressureAir pressure


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EarthsEarths MagnetosphereMagnetosphere

The Earth has aThe Earth has amagnetic field withmagnetic field withnorth and southnorth and south polespoles..The magnetic field ofThe magnetic field ofthe Earth is enclosedthe Earth is enclosed

in a regionin a regionsurrounding the Earthsurrounding the Earthcalled thecalled themagnetosphere.magnetosphere.

As the Earth rotates, itsAs the Earth rotates, its

hot corehot core generatesgeneratesstrong electric currentsstrong electric currentsthat produce thethat produce themagnetic field. Thismagnetic field. Thisfield reaches 36,000field reaches 36,000miles into space.miles into space.


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The magnetosphereThe magnetosphereprevents most of theprevents most of theparticles from the sun,particles from the sun,carried incarried in solar windsolar wind,,

from impacting thefrom impacting theEarth. The solar windEarth. The solar winddistorts the shape ofdistorts the shape ofthe magnetospherethe magnetosphereby compressing it atby compressing it atthe front and causingthe front and causing

a long tail to form ona long tail to form onthe side away fromthe side away fromthe Sun. This long tailthe Sun. This long tailis called theis called themagnetotail .magnetotail .


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The Earth as a PlanetThe Earth as a Planet


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The Earth is not aThe Earth is not a

perfect sphere.perfect sphere.

It is flattened at theIt is flattened at thepoles and bulgespoles and bulges

at the equator.at the equator.

The shape of theThe shape of the

Earth, called theEarth, called the

geoid.geoid.

The Planet EarthThe Planet Earth


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The Planet EarthThe Planet Earth

The Earth and its environmentThe Earth and its environmentmay be divided into severalmay be divided into severalrealms, the names of whichrealms, the names of whichend inend in --sphere.sphere.

These spheres includeThese spheres include thethe atmosphere,atmosphere,

lithospherelithosphere (rocks),(rocks),

thethe hydrospherehydrosphere (water),(water),

thethe biospherebiosphere (living things),(living things),andand

thethe magnetospheremagnetosphere (magnetic(magneticfields).fields).


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Earth's LithosphereEarth's Lithosphere

Geologists have learned that the inside of the Earth has many layers. TheGeologists have learned that the inside of the Earth has many layers. Theoutermost Earth layer is composed of rocks. It is called theoutermost Earth layer is composed of rocks. It is called the lithosphere.lithosphere. TheThelithosphere is about 100 kilometers (a bit more than 60 miles) thick. Thelithosphere is about 100 kilometers (a bit more than 60 miles) thick. Thelithosphere is not a solid shell of rock, but broken into large plates. Imagine alithosphere is not a solid shell of rock, but broken into large plates. Imagine ahard boiled eggshell that has been cracked on a table top, but the size of thehard boiled eggshell that has been cracked on a table top, but the size of theEarth. Unlike an eggshell, the plates of the lithosphere are not stationary. TheyEarth. Unlike an eggshell, the plates of the lithosphere are not stationary. Theyare all in constant motion. Plate movement is slow.are all in constant motion. Plate movement is slow.


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Because of increasing temperature and pressure, deeper portions of

the lithosphere are capable of plastic flow over geologic time. Thelithosphere is also the zone ofearthquakes, mountain building,

volcanoes, and continental drift.


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Earths LithosphereEarths Lithosphere

At the midAt the mid--ocean ridges, new rock isocean ridges, new rock isproduced by volcanism and the plates moveproduced by volcanism and the plates moveaway from each other.away from each other.

Where two plates approach each other,Where two plates approach each other,one is thrust downward into the mantleone is thrust downward into the mantlewhere it is heated and melted.where it is heated and melted.

Each red triangle represents the location ofEach red triangle represents the location ofan active volcano.an active volcano. Volcanoes areVolcanoes areconcentrated along plate boundaries.concentrated along plate boundaries.

Oceanic ridges are found where platesOceanic ridges are found where platesspread apart (diverge).spread apart (diverge).

Most surface volcanoes are located nearMost surface volcanoes are located nearconverging plate boundaries (subductionconverging plate boundaries (subductionzones), where two plates collide and onezones), where two plates collide and oneplate is driven beneath the other.plate is driven beneath the other.

Exceptions include volcanic Islands in theExceptions include volcanic Islands in themidmid--Pacific Ocean, which are formed as thePacific Ocean, which are formed as theplate moves over hotspots in the Earth'splate moves over hotspots in the Earth'smantle.mantle.


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Earths LithosphereEarths Lithosphere

Two hundred million yearsTwo hundred million yearsago all the Earth'sago all the Earth'scontinents formed a singlecontinents formed a singleland mass called Pangea.land mass called Pangea.

The continents began toThe continents began todrift apart about 150drift apart about 150million years ago.Today,million years ago.Today,the drifting continues. Forthe drifting continues. Forexample, every year Northexample, every year North

America moves 2America moves 2--33centimeters (about 1 inch)centimeters (about 1 inch)farther from Europe.farther from Europe.


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EarthsEarths HydrosphereHydrosphere

More than twoMore than two--thirdsthirdsof the Earthsof the Earthssurface is coveredsurface is coveredby water. In additionby water. In addition

to the oceans, theto the oceans, thehydrospherehydrosphereconsists of water inconsists of water inlakes and streams,lakes and streams,subsurface water,subsurface water,

the ice of glaciersthe ice of glaciersand water vapor inand water vapor inthe atmosphere.the atmosphere.


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The Earths AtmosphereThe Earths Atmosphere


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Earths AtmosphereEarths Atmosphere

Compared to the size of theCompared to the size of theEarth , the atmosphere is aEarth , the atmosphere is athin shell.thin shell.

The part of the atmosphereThe part of the atmospherewe know bestwe know best -- thethe

tropospheretroposphere -- is an evenis an eventhinner shell, only 12thinner shell, only 12kilometers (7.5 miles) thick.kilometers (7.5 miles) thick.

It is in the troposphere that allIt is in the troposphere that allweather occurs; it is only hereweather occurs; it is only herethat life exists.that life exists.

Space Shuttle Photograph of the EarthsSpace Shuttle Photograph of the Earthslimb. The thin atmosphere lighted by thelimb. The thin atmosphere lighted by thesetting Sun.setting Sun.


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Lets do thisLets do this

Cut off a strip of paper about 2.5 meterCut off a strip of paper about 2.5 meter

long 5 cm wide.long 5 cm wide.

Place a dot at the centre of the strip. ThisPlace a dot at the centre of the strip. Thisrepresent the centre of the Earth.represent the centre of the Earth.

Measure out from the dot 64 cm in eachMeasure out from the dot 64 cm in each

direction and draw a lines at the 64 cmdirection and draw a lines at the 64 cm

marks. This represent the earthsmarks. This represent the earths

diameter.diameter.scale - 1 cm: 100 km


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Now, draw lines at the proportional distances givenNow, draw lines at the proportional distances given

below from the surface of the earth and label thebelow from the surface of the earth and label the

atmospheric layers accordingly.atmospheric layers accordingly.

Troposhere (0 25 km) 0.12 cm

Stratosphere ((25 50 km) 0.48 cm

Mesosphere (50 -80 km) 0.95 cm

Thermosphere (80 400 km) 6 cm

Exosphere (400 1000 km) 10 cm


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You can add this data from the table below toYou can add this data from the table below to

your modelyour model

Highest mountain (Mt. Everest) (6.104 km) 0.06 cm

Deepest ocean trench (Marianas Trench) (11.033 km) 0.11 cm


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The water of the hydrosphere is in constant motion. Water evaporatesThe water of the hydrosphere is in constant motion. Water evaporatesfrom both the land and seas.from both the land and seas.

The water vapor in the atmosphere condenses to form clouds and fallsThe water vapor in the atmosphere condenses to form clouds and fallsas rain or snow. That which falls on land is carried, eventually, to theas rain or snow. That which falls on land is carried, eventually, to thesea to begin the cycle anew. This is the water, or hydrologic, cycle.sea to begin the cycle anew. This is the water, or hydrologic, cycle.


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lecture 7 earth as a planet

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