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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
24
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/Silica7/31/2019 IIT-GN EVS lecture 2
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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
dioxide, and other gases.23
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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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