iit-gn evs lecture 2

7/31/2019 IIT-GN EVS lecture 2

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Earth

Earth, Energy, and Environment

Fall 2012

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Third planet from the Sun

Densest

The fifth largest of eightplanets of the Solar System

The Planet Earth

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Earth formed 4.54 billion years ago

Life appeared on its surface within one

billion yearsThe planet is home to millions of species,

including humans.

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Earth Formation

The earliest dated solar system material was formed

4.567 billion years ago.

About 4.54 billion years ago the earth was formed

from the solar nebula- a disk shaped mass of dust andgas left over from the formation of Sun

Molten cooled and formed the out layer of solid

Earth as water begun accumulating in the atmosphere The moon formed about 4.53 billion years ago

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Release ofgases and volcanic activities produced initial

atmosphere of the Earth.

A combination of greenhouse gases and higher solar

activity raised the Earths temperature.

About 3.5 billion years ago Earths magnetic field was

formed

Earths magnetic field prevented the atmosphere beingstripped away from the solar winds

Earth Formation

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Earth Formation

Earth is a terrestrial planet (rocky body)

The largest of four solar terrestrial planets in size and

mass

Earth has the highest density, the highest surfacegravity, the strongest magnetic field, the fastest

rotation, and active plate tectonics.

Mercury, Venus, Earth, and Mars7


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Shape of the Earth

Oblate spheroid: a sphere flattened

along the axis from pole to pole

Diameter at the equator is about 43 km

larger than the pole-to-pole diameter

Average diameter is about 12,742 km

Compare: Mount Everest (8848 m)and Mariana Trench (10911 m)

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Chemical composition

Mass: 5.98 10

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kg Composed of :

Iron: 32.1 %

Oxygen: 30.1%

Silicon: 15.1%Magnesium : 13.9%

Sulfur: 2.9%

Nickel: 1.8 %

Calcium: 1.5%Aluminum: 1.4%

The core region is composed of 89 % iron.9


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Chemical Composition

Compound FormulaComposition

Continental Oceanic

silica SiO2 60.2% 48.6%

alumina Al2O3 15.2% 16.5%

lime CaO 5.5% 12.3%

magnesia MgO 3.1% 6.8%

iron(II) oxide FeO 3.8% 6.2%

sodium oxide Na2O 3.0% 2.6%

potassium oxide K2O 2.8% 0.4%

iron(III) oxide Fe2O3 2.5% 2.3%

water H2O 1.4% 1.1%carbon dioxide CO2 1.2% 1.4%

titanium dioxide TiO2 0.7% 1.4%

phosphorus

pentoxideP2O5 0.2% 0.3%

Total 99.6% 99.9%

About 47% of the Earths crust is made

of oxygen.

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http://en.wikipedia.org/wiki/Silicahttp://en.wikipedia.org/wiki/Aluminahttp://en.wikipedia.org/wiki/Calcium_oxidehttp://en.wikipedia.org/wiki/Magnesium_oxidehttp://en.wikipedia.org/wiki/Iron(II)_oxidehttp://en.wikipedia.org/wiki/Sodium_oxidehttp://en.wikipedia.org/wiki/Potassium_oxidehttp://en.wikipedia.org/wiki/Iron(III)_oxidehttp://en.wikipedia.org/wiki/Water_(molecule)http://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Titanium_dioxidehttp://en.wikipedia.org/wiki/Phosphorus_pentoxidehttp://en.wikipedia.org/wiki/Phosphorus_pentoxidehttp://en.wikipedia.org/wiki/Phosphorus_pentoxidehttp://en.wikipedia.org/wiki/Phosphorus_pentoxidehttp://en.wikipedia.org/wiki/Titanium_dioxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Water_(molecule)http://en.wikipedia.org/wiki/Iron(III)_oxidehttp://en.wikipedia.org/wiki/Potassium_oxidehttp://en.wikipedia.org/wiki/Sodium_oxidehttp://en.wikipedia.org/wiki/Iron(II)_oxidehttp://en.wikipedia.org/wiki/Magnesium_oxidehttp://en.wikipedia.org/wiki/Calcium_oxidehttp://en.wikipedia.org/wiki/Aluminahttp://en.wikipedia.org/wiki/Silica


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Internal Structure

Depth

km

Component

Layer

Density

g/cm3

060 Lithosphere

035 Crust 2.22.9

3560 Upper mantle 3.44.4

352890 Mantle 3.45.6

100700 Asthenosphere

28905100 Outer core 9.912.2

51006378 Inner core 12.813.1

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Heat

Earths heat comes from two sources:

Residual heat from planetary accretion (20%)

Radioactive decay (80%)

The major heat-producing isotopes in the Earth are:

Potesium-40, Uranium-238,235, and Thorium-232

At the center of the Earth, temperature may be up to

7,000 K and the pressure could reach 360 GPa.

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Tectonic Plates

Plate nameArea

106 km2

Pacific Plate 103.3

African Plate 78.0

North American Plate 75.9

Eurasian Plate 67.8Antarctic Plate 60.9

Indo-Australian Plate 47.2

South American Plate 43.6

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Convergent boundaries

Divergent boundaries

Transform Boundaries

Earthquakes, volcanic activities, mountain

building, and oceanic trench formation canoccur along these boundaries.

Tectonic Plates

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Surface

Earths surface consists of: Land andOcean

About 70.8 % of the surface is covered

with water.

The submerged surface has mountains,

volcanoes, trenches.

The other 29.2 % also has mountains,

deserts, plains, plateaus, and other

geomorphologic features.

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Surface

The shape of the Earths surface changes due to

tectonics and erosion.

The surface features builds up or deforms due to plate

tectonics are subjected to weathering fromprecipitation and thermal and chemical cycles

The continental crust consists ofigneous,

sedimentary, and metamorphic rocks.

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Pedosphere

The outermost layer of the Earth that is composed

of soil and subjected to the soil formation process.Pedosphere exists at the interface of lithosphere

and hydrosphere, biosphere, and atmosphere.

s = f (cl, o, r, p, t, ...)

S- Soil

Cl- Climate

O- Potential Biota

r- Relief/topography

p- parent material

t- time 18


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Hydrosphere

The abundance of water on the earth surface is a

unique feature due to which Earth is also known as

the Blue Planet.The hydrosphere includesoceans, lakes, ponds,

rivers, inland seas, and underground water up to

2000 m depth.

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Hydrosphere

About 97.5% water is saline, remaining 2.5 % is fresh

water and most (68 %) of the fresh water is in solid

form.

The average salinity of the sea water is about 35gm/kg.

Most of the salt was released from volcanic activities

or extracted from the cool, igneous rocks.

Sea water supports aquatic life, acts as a heat

reservoir, and controls weather and climate.

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Atmosphere

Source: MODIS

Earths atmosphere contains about 78 and 21%nitrogen and oxygen, respectively.

Rest are trace gases including water vapor, Carbon

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The height of thetroposphere varies between 8

to 17 km with lowest height

at poles while the highest at

the equator.

Some variations in

troposphere's height occur

due to changes in weatherand seasons.

Atmosphere

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Biosphere

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Future

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