Components and Layers of Earth's Atmosphere

W E L C O M E
Central University of Kerala

Ms. Ashila Babu. P
I Semester, Masters
Dept. Environmental Sciences
C e n t r a l U n i v e r s i t y oCentral e r a l a Kerala
f K University of

Uniqueness of mother Earth, what we believe created life on
it and those with which life is sustained and protected has
always dragged attention of environmentalists. Being so
advanced, as we all believe, fictions rules over facts when it
comes to sciences that explore both depths as well as the
open space above.

Here we’ve a brief note on basic known facts on
Environmental Segments & Structures


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Components of Atmosphere


Layers of the Atmosphere


The troposphere is the lowest layer of Earth's atmosphere.

The troposphere starts at Earth's surface and goes up to a height of 7 to 20 km
(4 to 12 miles); bounded from stratosphere by Tropopause.

Most of the mass (about 75-80%) of the atmosphere is in the troposphere.

Almost all weather occurs within this layer.
Air is warmest at the bottom of the troposphere near ground level. Higher
up it gets colder.

Air pressure and the density of the air are also less at high altitudes.

The troposphere is heated from below. Sunlight warms the ground or
ocean, which in turn radiates the heat into the air right above it.

Most clouds are found in the troposphere.

The stratosphere is the second layer (going upward) of Earth's
atmosphere; bounded above by stratopause.

Boundaries : Lower - Near the equator - aroud16km(10miles)
Near the mid latitudes- around 10km(6miles)
Near the pole- around 8km(5miles)
Upper - 50km(31 miles)

Features : Forms about 20-25% of total atmospheric mass
Ozone layer situates in this layer
Commercial jet aircraft fly in the lower stratosphere to avoid
the turbulence which is common in the troposphere below.
Air is roughly a thousand times thinner at the top of the
stratosphere than it is at sea level. Because of this, jet
aircraft and weather balloons reach their maximum
operational altitudes within the stratosphere.

Mesosphere (In Greek, “meso” means “middle”)

The mesosphere is the third layer (going upward) of Earth's
atmosphere; bounded above by mesopause.

This layer ranges between 45 to 92 km
Forms less than 1% of the total mass
Sharp decline in temperature -93°C (-137°F) at top

Boundaries : Lower -The mesosphere starts at 50 km (31 miles) above
Earth's
Upper -The mesosphere goes up to 85 km (53 miles) high
As you get higher up in the mesosphere, the temperature gets colder.
The top of the mesosphere is the coldest part of Earth's atmosphere.
[ -90°C (-130° F)]!
Most meteors from space burn up in this layer.

About mesosphere….!

Scientists know less about the mesosphere than about
other layers of atmosphere. The mesosphere is hard to study.
Weather balloons and jet planes cannot fly high enough to
reach the mesosphere. The orbits of satellites are above the
mesosphere. But we do get some measurements using
sounding rockets which makes a short flights.


Thermosphere (from the Greek “therme” meaning heat)

The Thermosphere is the fourth layer (going upward) of Earth's
atmosphere; bounded above by thermopause.
It extends from about 90 km (56 miles) to between 500 and 1,000 km
(311 to 621 miles) above our planet.

Temperature :
Lower thermosphere (below 200 to 300 km altitude)-about 200° C
(360° F), hotter in the daytime than at night; and roughly 500° C (900°
F) hotter when the Sun is very active than at other times.
Upper thermosphere: can range from about 500° C (932° F) to 2,000°
C (3,632° F) or higher.


About thermosphere….!

The space shuttle and the International Space Station both orbit
Earth within the thermosphere!

Much of the X-ray and UV radiation from the Sun is absorbed in
the thermosphere.

The aurora (the Southern and Northern Lights) primarily occur in
the thermosphere.


Very high up, the Earth's atmosphere becomes very
thin. The region where atoms and molecules escape
into space is referred to as the exosphere. The
exosphere is on top of the thermosphere.


Other Layers of Atmosphere

Ionosphere : Scientists call the ionosphere an extension
of the thermosphere.
High-energy solar photons tear electrons away
from gas particles in the thermosphere, creating
electrically-charged ions of atoms and molecules
which creates the ionosphere.

Ionosphere is broken down into the D, E and F
regions. The breakdown is based on
what wavelength of solar radiation is absorbed in
that region most frequently.


The D region is the lowest in altitude, though it absorbs the
most energetic radiation, hard x-rays. The D region doesn't have a
definite starting and stopping point, but includes the ionization
that occurs below about 90km.

The E region peaks at about 105km. It absorbs soft x-rays.

The F region starts around 105km and has a maximum
around 600km. It is the highest of all of the regions. Extreme ultra-
violet radiation (EUV) is absorbed there.


On a more practical note, the
D and E regions reflect AM radio
waves back to Earth. Radio waves
with shorter lengths are reflected
by the F region. Visible light,
television and FM wavelengths are
all too short to be reflected by the
ionosphere. So your TV stations
are made possible by satellite
transmissions.


Ozonosphere : The ozone layer is a range of altitudes in
Earth's stratosphere which has a higher concentration
of ozone molecules.
Ozone is an unusual type of oxygen molecule. It is
created when high-energy ultraviolet light from the
sun, strikes a normal oxygen molecule.

The ozone layer extends from roughly 15 to 35 km (9
to 22 miles) above sea level. The peak of ozone
concentration is between 20 and 25 km(12 and 16
miles).


Also…

Ozone layer protects us from UV radiation in sunlight and
acts like a sunscreen for planet Earth.

The ozone layer stops almost all of the incoming UV-C, about
90% of the UV-B, and roughly half of the UV-A radiation.

The ozone molecules which absorb UV radiation later re-
radiate the energy as heat, warming the stratosphere.


Ozone Depletion

Various chemicals that human release into the
atmosphere can destroy ozone in the stratosphere.

In the 1980s, scientists noticed that the ozone layer was
thinning.

They also noticed huge holes in the ozone layer,
especially over Antarctica.

They convinced people and governments around the
world to reduce emissions of ozone-destroying
chemicals. They hope the ozone layer will heal itself
over time.

Homosphere (“homo” means “same”)

Well-mixed gases from 0-80 km.

Heterosphere (“hetero” means “different”)

Settling of gases according to weight
above 80 km.


The outer part of the Earth, consisting of the crust
and the upper mantle. It is about 55 km (34 mi) thick
beneath the oceans and up to about 200 km (124 mi)
thick beneath the continents. The high velocity with
which seismic waves propagate through the
lithosphere suggests that it is completely solid, when
comparing with asthenosphere, atmosphere,
hydrosphere.


The core is a layer rich in iron and nickel found in
the interior of the Earth. It is composed of two
sub-layers: the inner core and outer core. The core
is about 7,000 kilometers in diameter.

The Earth's core is solid mass of iron plus some
nickel surrounded by a fluid (water-like) outer
layer. The closer you get to the core, the hotter it
becomes and the greater the pressure.
Other factors affect the gravity field too..

Inner Core : Inner region of the Earth's core. It
is thought to be solid iron and nickel with a
density of about 13 grams per cubic centimeter.
It also has a diameter of about 1220
kilometers. Also known as siderosphere.

Outer Core : Outer region of the Earth's core. It is
believed to be liquid nickel and iron and has a
density of about 11 grams per cubic centimeter. It
surrounds the inner core and has an average
thickness of about 2,250 kilometers.


Earth's outer most layer of solid rock. Between
7 to 70 kilometers thick.

Two types of crust exist:

Oceanic crust and Continental crust.


Oceanic Crust : Basaltic portion of the Earth's crust that
makes up the ocean basins. Approximately 5 to 10 kilometers
thick.

Sima Layer : The part of the crust that forms the ocean
basins and lower layers in the crust and is composed of relatively
heavy, basaltic rocks.

Continental Crust : Granitic portion of the Earth's crust that
makes up the continents. Thickness of the continental crust varies
between 20 to 75 kilometers.

Sial Layer : The part of the crust that forms the continents and
is composed of relatively light, granitic rocks.

Layer of the Earth's interior,
composed of mostly solid rock that
extends from the base of crust to a
depth of about 2,900 kilometers.


The Hydrosphere is the total water presence on
the earth, so encompassing that found in the
largest oceans and the smallest ponds, in the soil
and that contained in the air. Along with the
atmosphere, the biosphere and the geosphere.


Oceans-96.5% of water found here

Fresh water-3.5% water found here
Ice -1.762%(Ice bergs, Glaciers, Snow..)
Ground water-1.7%
Surface fresh water-0.014%
Atmosphere & soil-0.002%


What is the difference between watershed and river basin?

River basin: The term used to describe an area that drains into a large
river

Watershed: The term used to describe an area that drains into smaller
river or stream.

Larger river basins are made up of many inter connected watersheds.

The water in a watershed runs to the lowest point- river, stream or
ocean.

E.g. : River Ganga & Brahmaputra are made up of many small
watersheds.


 River : A large channel along which water is
continually flowing down a slope made of
many stream that comes together.
 Stream : A small channel along which water is
continually flowing down a slope made of
small gullies.
 Lake : A body of water of considerable size
contained on a body of land.
 Ground water : the water found in the cracks
and pores in sands, gravels and rocks
below the earth’s surface.
 Aquifer : a porous rock layer underground
that is a reservoir


Wetland : An area where the water the water table is at, near
or above the land surface long enough during the year
to support plant growth.

Types: swamps, bogs and marshes.
Swamps- a wet land dominated by trees
Bogs-a wet land dominated by peat moss
Marshes- a wet land dominated by grass.


The biosphere is the outermost part of the planet's shell,
including air, land, surface rocks, and water within
which life occurs, and which biotic processes in turn
alter or transform. From the broadest bio-physiological
point of view, the biosphere is the global ecological
system integrating all living beings and their
relationships, including their interaction with the
elements of the lithosphere(All the nonliving things that
make up the earth(dirt, rock, etc.), hydrosphere (The
Oceans, river, etc.), and atmosphere (Air and its
"relatives", hydrogen, Co2, etc.). This biosphere is
postulated to have evolved, beginning through a
process of biogenesis or biopoesis, at least some 3.5
billion years ago.


Contd..

The parts of the land, sea, and atmosphere in
which organisms are able to live. The biosphere
is an irregularly shaped, relatively thin zone in
which life is concentrated on or near the Earth's
surface and throughout its waters.


The Biosphere is organized in a hierarchical structure in which
individual organisms are organized into Populations.

Several interacting populations form Biotic Communities.

And a distinctive community living in a certain physical
environment forms an Ecosystem.

An ecosystem is a group of animals, plants, and microbes
interacting with each other and with their physical
environment in such a way as to ensure their existence.


Cont..
Hence an ecosystem is the functional unit of sustainable life
on Earth.

No individual cell, population, or biotic community forms a
sufficient entity to support life.

In general, ecosystems do not have sharp boundaries. Instead
there are gradational or transitional communities referred to
as Ecotones.

Several related or similar groups of ecosystems are known
as Biomes.

Biomes are grouped into two distinct categories:
Terrestrial
Aquatic Central University of Kerala

Terrestrial biomes:
Consist of ecosystems inhabiting land environments
such as tundra, temperate grasslands, tropical forests or
hot deserts; whereas aquatic biomes consist of water-
dwelling ecosystems such as pelagic, and
benthic freshwater ecosystems.

Aquatic biomes:
They are typically distinguished by salinity, climate, and
water depth.


Despite the variations among ecosystems, they
all share a common structure due to common
functions of basic processes within each
ecosystem.
 They all engage in energy transfer within the
community , and energy in an ecosystem flows
in one direction.
 They all must recycle various chemical
substances required for growth, reproduction,
and protection.

Contd..

As a result, the basic biotic structure is
based on feeding relationships.
The producers, consumers, and detritus
feeders and decomposers are the basic
feeding categories that allow energy
and matter to flow through
ecosystems. All organisms must feed to
satisfy the basic processes listed above.

In addition to biological factors such as the food web,
there are physical and chemical factors that determine
the survival of an organism in an ecosystem, and can
also affect structure of the ecosystem.

The abiotic (non-biological) factors in an aquatic
environment would include salinity, temperature,
light, chemical nutrients, bottom substrate, water
depth, water clarity or turbidity, and currents.


Contd..

Coral reefs, for example, require very low
turbidity (maximum light), moderate to high
temperatures (tropical climates), shallow
depths (for effective light penetration and
temperature limitations), and moderate to high
salinity (30 - 40 ppt) to survive.
A coral reef ecosystem will not develop if all of
these abiotic factors are not met.


Biosphere 2 is an Earth systems
science research facility currently owned
by the University of Arizona since 2011. Its
current mission is to serve as a center for
research, outreach, teaching and lifelong
learning about Earth, its living systems,
and its place in the universe. It is a 3.14-
acre (12,700 m2) structure originally built to
be an artificial, materially closed ecological
system in Oracle, Arizona (US)


 To serve as a center for research, outreach, teaching
and life-long learning about Earth, its living systems,
and its place in the universe.

 Catalyze interdisciplinary thinking and understanding
about Earth and its future.

 Be an adaptive tool for Earth education and outreach to
industry, government, and the public.

 Distill issues related to Earth systems planning and
management for use by policymakers, students and the
public.

Biosphere 2 arena

Oracle, Arizona (US)


Image
Gallery

Queries…..!


Ms. Ashila Babu. P
I Semester, Masters
Dept. Environmental Sciences
C e n t Central University s i Kerala f K e r a l a
r a l U n i v e r of t y o

Components and Layers of Earth's Atmosphere

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