Download Origin of the atmosphere and ocean First read this verse: Earth`s

‫‪Origin of the atmosphere and ocean‬‬
‫‪First read this verse:‬‬
‫•‬
‫يقول هللا تعالى‪:‬‬
‫”الذين يذكرون هللا قياما وقعودا وعلى جنوبهم ويتفكرون‬
‫فى خلق السموات واألرض ربنا ما خلقت هذا باطال‬
‫سبحانك فقنا عذاب النار“‬
‫سورة آل عمران‪ ,‬آيه ‪191‬‬
Origin of the atmosphere and ocean
• Earth’s surface solidifies gradually
in a period ranging from 50 to 100
millions yrs. This solidification of
the Earth’s crust that occurred
about 4.5 billion yrs ago, marks the
beginning of the Geologic History
on Earth. At this stage, the Earth
lost its original gas envelope and
its crust became cool.
• The volcanic activity and meteor
bombardment were still intense
until 3.9 billion yrs.
Formation of the atmosphere
• Volcanic activities
released much
quantities of water vapor (H2O),
carbon dioxide (CO2), chlorine gas
(Cl2), hydrogen and Nitrogen (N2).
Also, methane (CH4) and ammonia
(NH3) occurred.
• As Earth cooled, the water vapor in
the atmosphere condensed and fell
to the Earth’s surface to form the
ocean water at about 4 billion yrs
ago.
Origin of ocean water
•
Two assumptions explaining the ocean water sources:
1- From the Mantle where the water vapor is brought out to
the atmosphere via the volcanic activities, then
condensed to fall on the earth’s surface forming the
ocean water that is in permanent existence since its
formation at 4 billion yrs ago (fossilized algae, marine
environment).
What is the evidence for this assumption?
Mantle volume=1027cm3, density=4.5 g/cm3
Mantle mass=4.5*1027 g
Ocean water mass=1.4*1024 g
So, mantle must have lost 0.031% of its mass
Meteorites contain 0.5% water which is about 16 times bigger than the
loss required from the
mantle to account for the present ocean water.
‫يقول هللا تعالى‪:‬‬
‫”واألرض بعد ذلك دحاها ‪ .‬اخرج منها مآءها ومرعاها ‪.‬‬
‫والجبال ارساها ‪ .‬متاعا لكم وألنعامكم“‬
‫سورة النازعات‪ ,‬آيه (‪)33-30‬‬
2- From the space (Louis Frank, space scientist): Ocean water
came to earth as comet-like ball of ice about 9 m in diameter
entering to the earth’s atmosphere via dark holes (48 km wide)
by rate of about 20 per minute. So, earth would receive 0.0025
mm of water per yr. In four billion yrs, the ocean would fill to
the present volume.
Since that time ocean water started to recycle
to account for the eroded sedimentary
succession on earth, with new little addition (1%) from
the mantle by the volcanic activities.
Thurman balance supports this assumption!
Ocean salinity
•
Salinity is a measure of number of ions (e.g. Cl-, Na+, Ca++, K+,
Mg++, SO4--) in the ocean water.
•
Present day ocean salinity averages 35 ‰.
•
Salinity measures the number of ions (Cl-, Na+, Ca++, K+, Mg++,
SO4--) in the ocean water. These ions are referred to as the
major or conservative ions. They constitute over 99.8 % of the
mass of solutes dissolved in seawater.
•
Salinity defined as the total number of grams of dissolved salt
ions present in 1 kg of seawater. Mathematically expressed as
parts per thousand (‰).
•
The most important component (ion) of salinity is the
chlorine ion (Cl-), which is produced by volcanic
activities. At 4.5 billion years, ocean water formed from
the condensation of the atmosphere volatiles and water
water vapor (H2O). Since that time, salinity developed in
the ocean due to adding more substances from the
rainfalls and earth's crust and is relatively constant with
no indication of any major fluctuations in this ratio
throughout the geologic time.
Origin of life on the earth
• Life on the earth started in the ocean
• Many possibilities explain the 1st organic compound on the
Earth:
1. May come from meteorites, comets cosmic dust.
2. Hydrothermal vents
• To have life organic matter on the Earth, the atmosphere
must contain free oxygen for respiration.
• What do you expect for the amount of free oxygen in the
initial atomsphere?
Constituent of current Percent by Volume
atmosphere
(Dry Air)
Nitrogen (N2)
Oxygen (O2)
Argon (A)
Carbon Dioxide (CO2)
Trace Constituents
78.084%
20.946%
0.934%
0.0332%
0.0028%
The initial atmosphere composition
inferred from the Volcanic Emissions
Percent By
Volume
Water Vapor (H2Ov)
79%
Carbon Dioxide (CO2)
12%
Sulfur Dioxide (SO2)
7%
Nitrogen (N2)
1%
Hydrogen (H2)
0.5%
•
The earliest atmosphere had 0.0 of oxygen due to the
oxidation process during this time. Reduced nature of
chemical substances in the volcanic rocks and gases,
prevent any occurrence of free oxygen (O2) due its rapid
consumption by oxidizing of these substances.
•
Evidence: all the volcanic rocks contain iron as Ferrous iron.
8 FeO + 2 O2
•

4 Fe2O3
Where did 1st life (plant) on Earth get free oxygen?
From the pyrite (Fe2S) formation:
FeO + S
Fe2S + O2 (free oxygen for life usage)

From the photodissociation of water in the upper layers of
the atmosphere.
H2O + UV )ultraviolent radiations( → H2 + O2
•
Life started in the ocean in an anaerobic environment, probably by this
way
Methane (Ch4)
Ammonia (Nh3)
H2
N2
C and CO2
Electrical spark and
Ultraviolent radiations
Organic matter molecules
•
These conditions allow the formation of the organic matter
by photosynthesis in the absence of chlorophyll. Once the
1st single life cell formed, the plants evolved producing free
oxygen to the atmosphere by photosynthesis.
 Photosynthesis process:
6H2O + 6CO2 + Energy
C6H12O6 + 6O2
An experiment (Miller, 1952): Synthesis of organic carbon (amino acids). A
mixture of water vapor, methane, ammonia and hydrogen was subjected to
an electrical spark that provided the energy for synthesis. From Thurman,
1997.
•
1st recorded Bacteria-cell like at 3.5 billion yrs
•
The earliest photosynthesis led to:
1.
Increase the free oxygen to make up 21% of the present atmosphere
which was one-tenth of the present day value.
2. Reduce the CO2 at present to 0.03% which was about 25% of the
earliest atmosphere. What do you expect for the earliest atmosphere?
3. Sun became progressively hotter, so CO2 taken out from the
atmosphere and stored on the ocean floor and on the continent as
carbonate rocks. This led to gradual cooling of the earth.
4. Formation of the Ozone layer.

When plants evolved more and more, taking CO2 in their tissue the
earth cooled to become pleasant for life. The study of fossil plants and
animals could tell us more information about the earth's history.
Earth’s Rotation and the orbital forcing
•
Earth rotates around the sun with speed averaging 1000
mile/hour. Direction of rotation is towards the east.
•
The vertical axis of the earth is not perpendicular on the plane
of the Ecliptic. It tilts by about 23.5 degree.
•
This tilt is responsible about the formation of the four seasons
(summer, autumn, winter and spring) on the earth through the
year.
•
Changes of the Earth’s Orbits around the sun resulted in many
climatic cycles. These changes known as Orbital Forcing:
1- Eccentricity (100,000 yrs)
2- Precession (21,000 yrs)
3- Obliquity (41,000 yrs)
Eccentricity
The shape of the Earth's orbit around the Sun. It varies between
more or less elliptical on a cycle of about 110,000 years. (This 110
000 year cycle is actually a combination of a 100 000 year cycle,
and a much weaker one of 413 000 years.
Obliquity
Axial tilt refers to the inclination of the Earth's axis in relation to its plane of
orbit with the Sun.This inclination oscillates in a range of 21.8o and 24.4o. It
takes the Earth about 41,000 years to move through this range. The
difference in tilt affects where on the Earth receives the most and least
solar radiation, but has global climatic consequences.
Precession
Earth does not have a perfect
spin about its axis. It wobbles,
and this wobble is defined as
precession. This Earth 'wobble'
is with respect to the direction
its rotational axis points. Within
the framework of the stars, it
represents a change of direction,
from
having
the
North
pole
pointing at the North Star, to
having the North pole pointing at
the star Vega.
Figure showing the changes of
the Earth’s orbit and the tilt
that result in changes in the
insolation intensity from the
sun. Consequently, three
common climatic cycle are
formed, called Eccentricity,
Obliquity and Precession.