3. LESSON OBJECTIVE
To learn the basic knowledge of Earth’s sphere and its interrelationship
To understand the Earth’s system
To learn the evolution of Earth
8. ATMOSPHERE
Earth is surrounded by life giving gaseous envelope
Atmosphere is thin and tenuous
An integral part of planet
Not only for breathing but also protects us from the Sun’s intense heat and dangerous UV radiation.
Exchange of energy between atmosphere and Earth surface and between the atmosphere and space
produce effects called weather and climate
10. BIOSPHERE
All life on Earth
Most life concentrated near surface, tree roots and burrowing
animals, flying insects and birds
Some of the life found in extreme environment
Organisms depends on physical environment
12. GEOSPHERE
Lying beneath the atmosphere and the oceans is the solid Earth or
geosphere
it extends from surface to center of the Earth
Largest of four Earth’s sphere
Dynamic behavior of earth’s interior
Soil is a thin layer of Earth’s surface
13. SOIL
The solid portion is a mixture of weathered rock debris
(geosphere) and organic matter from decayed plant and
animal life (biosphere). The decomposed and
disintegrated rock debris is the product of weathering
processes that require air (atmosphere) and water
(hydrosphere).
15. EARTH AS A SYSTEM
Our planet is a dynamic body with many separate but interacting parts or spheres.
Each is related in some way to the others to produce a complex and continuously interacting whole
that is called Earth system
16. CYCLES IN THE EARTH SYSTEM
Hydrologic cycle is an important subsystem
Unending circulation of Earth’s water among the four spheres
17. CYCLES IN THE EARTH SYSTEM
The rocks of the geosphere are constantly forming, changing and
reforming.
The loop that involves the processes is called rock cycle
These cycle are not independent
18. CYCLES IN THE EARTH SYSTEM
Hydrologic cycle and rock cycle:
1. Weathering, disintegrate and decompose
2. Movement and deposition
3. GW percolate through debris
4. leave mineral matter which help to cementing
5. Changing from one rock to another would not possible without hydrologic cycle
Figure: 1.13 (Tarbuck)
19. ENERGY FOR THE EARTH SYSTEM
Two sources of energy:
1. The Sun
2. The Earth’s interior
20. The Sun:
Drives external processes
Weather and climate
Ocean circulation
Erosional processes
Earths interior:
Decay of radioactive elements
Volcanoes
Earthquakes
Mountains
21. ORIGIN OF PLANET EARTH
Big bang occurred 14 billion years ago
A large explosion that sent all matter of the universe flying outward
at incredible speeds.
The debris from the explosion was almost entirely hydrogen and
helium
Began to cool and condense into the first stars and galaxies
One of the galaxies was Milky way galaxy, where our solar system
and planet earth took place
22. ORIGIN OF THE SOLAR SYSTEM
Gaseous hypothesis of Kant
Nebular hypothesis of Laplace
23. GASEOUS HYPOTHESIS OF KANT
Immanuel Kant- German Philosopher
Book “ The General Natural History and Theory of the Heaven” in 1755
His assumptions–
Supernaturally created primordial hard matter was scattered in the
universe
In fact, slowly rotating cloud of gas (nebula) and matter comprised of very
cold, solid and motionless particles
The particles began to collide with each other due to gravitational
attractions
24. This attraction and collision generated random motion and heat
With temperature the random motion/rate of collision also increases
Temperature rise changed the solid primordial matter to gaseous particle
Heat increases so as the size of the nebula and angular velocity
Rapid spin results in the separation and thrown off of irregular rings from
the nebula
Similar way nine rings (planets) were separated from the nebula
The central mass of the nebula remained as the sun
25. Limitations of Gaseous hypothesis of Kant
The source or the origin of the primordial matter
Source of energy to cause random motion
Increase of rotatory speed with size
26. NEBULAR HYPOTHESIS OF LAPLACE
Modified version of Kant’s hypothesis
French Mathematician Laplace in his book “
Exposition of the World System” in 1796
His assumptions
There was a hot and rotating gaseous nebula in
space
Gradual loss of heat from the outer surface due
to motion/rotation
27. This gradual loss of heat resulted in the cooling
of the outer surface and contraction of size
and volume of the nebula
As the size decreases, the nebula started
spinning at very fast speed
As a result centrifugal force (out of the centre)
became greater the centripetal force (towards
centre)
28. • The condensed and cooled outer ring could not
rotate with the central nucleus
• separated from the nebula
• This separated ring also started moving around
the nebula
• The separated ring was divided into nine rings
(hot gaseous agglomeration) moved away from
one another
• These hot gaseous agglomeration was cooled
and condensed to form planets
• The remaining central nucleus became the sun
