2. DOMAINS OF ENVIRONMENT
Lithosphere: The solid portion of the earth
Atmosphere: The gaseous layers that surround the earth
Hydrosphere: Water covers a very big area of the earth’s surface and this area is
called the Hydrosphere
Biosphere: It is the narrow zone where land, water and air together are found.
The term was coined by JOSEPH BARRELL (1914).
The lithosphere is a domain concerning land. When land is measured, it is
measured by taking sea level as it’s base.
The height of the land is also measured by denoting it as either ASL (Above Sea
Level) or BSL (Below Sea Level).
The Earth is divided into 7 continents. Asia, Europe, Africa, North America, South
America, Antarctica, and Australia. Continents are the most important domain as
they inhibit the largest number of life forms.
Asia is the largest continent on Earth covering almost 1/3rd of the Earth’s land.
Asia and Europe together form ‘Eurasia‘. It is followed by the continent of Africa.
Africa is unique in its own way because it is the only continent through which the
Equator, the Tropic of Cancer, and the Tropic of Capricorn pass through.
Europe is located entirely in the Northern Hemisphere as well as some of it lies in
the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic
Ocean to the west, and the Mediterranean Sea to the south.
North America and South America together form ‘Americas’. North America is
the third largest continent on Earth. Isthmus of Panama connects North America to
South America. The Northern Hemisphere is also called the Land Hemisphere
because the greater part of Earth’s landmass lies in the Northern Hemisphere.
Australia also known as Oceania is an island continent surrounded by the Indian
and Pacific oceans. It is known for its, the Great Barrier Reef, a vast interior desert
wilderness called the Outback, and unique animal species like kangaroos and duck-
billed platypuses which are found nowhere else.
Antarctica is the southernmost continent and site of the South Pole, it is a virtually
uninhabited and is in the completely ice-covered land. Australia and Antarctica
entirely lie in the southern hemisphere.
It is composed of crust & upper mantle which constitute the hard & rigid outer
layer of the earth. It includes rocks and soil which is actual medium of growth of
plants and animals and microorganisms .The lithosphere is thicker in continents
than oceans floor.
Crust: the crust is the outermost layer of the planet, the cooled and hardened part of
the Earth that ranges in depth from approximately 5-70 km (~3-44 miles).
Oceanic Crust :The bottom layer of this is composed of Silicon & Magnesium so its
called as SIMA.
It is thinnest layer. Its thickness is only 5-10km.
Oceanic crust is made mostly of rocks with a composition of basalt ( a dark colored
The uppermost layer of this is composed of Silicon & Aluminum so its called SIAl,
which has a depth of about 32 to 40km.
Continental crust is mostly made of rocks with composition of granite ( a light
It is It is the second layer of the earth and extends from 30km- 2900km with an
average density of 2.7 g/cm3
It contains 83% of the total volume and 68% of the total mass of the earth.
It is made up of silicate rich iron and magnesium and is divided from the crust by a
discontinuity called as MOHOROVICIC DISCONTINUITY.
Diamonds are tiny pieces of the mantle we can actually touch. Most form at depths
above 200 kilometers (124 miles). But rare “super-deep” diamonds may have formed
as far down as 700 kilometers (435 miles) below the surface. These crystals are then
brought to the surface in volcanic rock known as kimberlite.
The mantle’s outermost zone is relatively cool and rigid
It is the deepest layer of earth. It extends from a distance of 2900km – 6371 km with
an average density of 4.3- 11 g/cm3. Mantle and core boundary is called as
WEICHART- GUTENBERG Discontinuity.
Core volume is 16% of earth’s total volume and core mass is 32% of earth’s total
mass. It is further divided into 2 sub-zones by the discontinuity called as
LEHMANN- BULLEN Discontinuity.
• OUTER CORE: (2890km- 5150km)
• INNER CORE: (5150km-6371km):
The inner core:
This solid metal ball has a radius of 1,220 kilometers (758 miles), or about three-
quarters that of the moon. It’s located some 6,400 to 5,180 kilometers (4,000 to 3,220
miles) beneath Earth’s surface. Extremely dense, it’s made mostly of iron and nickel.
The inner core spins a bit faster than the rest of the planet.
The outer core:
This part of the core is also made from iron and nickel, just in liquid form. It sits
some 5,180 to 2,880 kilometers (3,220 to 1,790 miles) below the surface. Heated
largely by the radioactive decay of the elements uranium and thorium, this liquid
churns in huge, turbulent currents.
The domain of water is referred to as hydrosphere. It comprises various sources of
water and different types of water bodies like rivers, lakes, seas, oceans, etc. It is
essential for all living organisms.
Water is the most abundant substance at the surface of Earth. About 1.4 billion cubic
km (326 million cubic miles) of water in liquid and frozen form make up the oceans,
lakes, streams, glaciers, and ground waters found there.
It is this enormous volume of water, in its various manifestations, that forms the
discontinuous layer, enclosing much of the terrestrial surface, known as the
Only 2.5% of Earths water is freshwater. And even in this 2.5%; approximately 69%
is in the form of snow and ice.
15. HYDROSPHERE- FRESH WATER
Its about 97 percent of the earth’s water are stored in the earth’s oceans. All other
waters that is fit for human consumption and agriculture is called fresh water.
The basic source of fresh water is precipitation, but not all precipitation ends up as
part of the freshwater supply.
Water moving across the surface is called runoff. Runoff begins as rain accumulates
in thin sheets of water that move across the surface of the land.
These sheets collect into a small body of running water is called stream. A stream is
defined as any body of water that is moving across the land
17. HYDROSPHERE- GROUND WATER
Water that soaks into the ground moves down to a saturated zone where it is called
Groundwater moves through sediments and rocks beneath the surface,
slowly moving downhill.
An intermittent stream is one in which the source of groundwater is in low supply
and flow only part of the time. The amount of rainfall that becomes runoff or
groundwater depends on the following factors:
1. The type of soil in the surface
2. how dry the soil is
3. the amount and type of vegetation
4. the slope of the land
5. if the rainfall is a long, gentle one or a cloudburst
18. HYDROSPHERE- SURFACE WATER
The land area drained by a stream is known as the stream’s drainage Waters basin or
A line called divide separated two adjacent watersheds.
A continental divide separated river systems that drain into opposite sides of a
A smaller body of standing water is called a pond, and one of much larger size is
called a lake.
A natural pond or lake created by building dam is called a reservoir.
20. HYDROSPHERE- SURFACE WATER
It is used for:
Water storage- A reservoir for water storage is kept as full as possible to store water.
Flood control- A reservoir for flood control requires low water level in order to catch
runoff, preventing waters from flooding the land.
Generating electricity- A reservoir used to generate electricity requires the release
of water from the reservoir. The water of streams, ponds, lakes and reservoirs are
sources of fresh water and is collectively called surface water
21. HYDROSPHERE- OCEAN WATER
Five Major Oceans in order of their size are
Pacific Ocean: It is almost circular in shape. Asia, Australia, North and South
Americas surround it.
The Atlantic Ocean: It is the second-largest ocean in the world. It is ‘S’ shaped. It is
flanked by the North and South Americas on the western side, and Europe and Africa
on the eastern side.
The Indian Ocean: It is the only ocean named after a country, that is, India. The
shape of the ocean is almost triangular. In the north, it is bound by Asia, in the west
by Africa and in the east by Australia.
The Southern Ocean: It surrounds the continent of Antarctica
The Arctic Ocean: It is located within the Arctic Circle and surrounds the North
Pole. The Bering strait a narrow stretch of shallow water connects it with the Pacific
22. Ocean Facts
• The Pacific Ocean is the largest of the four main oceans
• The Atlantic Ocean is the busiest ocean. Many ships cross the Atlantic, carrying
cargo between the Americas, Africa, and Europe
• The Arctic Ocean is the smallest and coldest ocean
• The average temperature of all oceans is about 39 degrees F (3.8 degrees C)
• Oceans are always moving
• Tides change twice a day all over the world, as the oceans rise and fall along the
shoreline. Scientists think this is caused by the pull of the sun and moon on our
Earth, and the Earth's rotation.
• Coral reefs are vast, rocky areas located in shallow, tropical waters. Coral reefs are
like the tropical rain forest of the ocean in that the greatest variety of plant and
animal life in the ocean live there. Coral reefs are formed from the bodies of small
sea creatures called polyps
• The world's oceans contain nearly 20 million tons of gold
The earth is surrounded by a layer of gas called the atmosphere.
The atmosphere extends up to a height of about 1,600 kilometres.
The atmosphere is divided into five layers based on composition, temperature and
other properties and they are:
• the troposphere
• the stratosphere
• the mesosphere
• the thermosphere
• the exosphere
About 99 per cent of clean and dry air in the atmosphere is composed mainly of
nitrogen and oxygen. Nitrogen 78 per cent, oxygen 21 per cent and other gases
like carbon dioxide, argon and others comprise 1 per cent by volume.
Exosphere—contains few particles that move into and from space.
Exobase—the lower boundary of the exosphere.
Thermosphere—temperature increases with height. The temperatures can rise to
1,500 degrees Celsius, but it would not feel warm because of the low air pressure
in this layer.
mesopause—the boundary between the mesosphere and the thermosphere; the
coldest place on Earth.
mesosphere—the layer in which most meteors burn up after entering Earth’s
atmosphere and before reaching Earth’s surface.
stratopause—the boundary between the mesophere and the stratosphere.
stratosphere—contains the ozone layer; the layer where volcanic gases can affect
tropopause—the boundary between the stratosphere and troposphere.
troposphere—the layer closest to Earth’s surface in which all weather occurs.
27. ATMOSPHERE LAYERS IN DETAILS
The Troposphere: This is the lowest part of the atmosphere - the part we live in. It
contains most of our weather - clouds, rain, snow. In this part of the atmosphere
the temperature gets colder as the distance above the earth increases, by about
6.5°C per kilometre.
The troposphere contains about 75% of all of the air in the atmosphere, and almost
all of the water vapour (which forms clouds and rain).
The Stratosphere: This extends upwards from the tropopause to about 50 km. It
contains much of the ozone in the atmosphere.
The increase in temperature with height occurs because of absorption of ultraviolet
(UV) radiation from the sun by this ozone. Temperatures in the stratosphere are
highest over the summer pole, and lowest over the winter pole
28. ATMOSPHERE LAYERS IN DETAILS
By absorbing dangerous UV radiation, the ozone in the stratosphere protects us
from skin cancer and other health damage.
However chemicals (called CFCs or freons, and halons) which were once used in
refrigerators, spray cans and fire extinguishers have reduced the amount of ozone
in the stratosphere, particularly at polar latitudes, leading to the so-called
"Antarctic ozone hole".
The Mesosphere: The region above the stratosphere is called the mesosphere.
Here the temperature again decreases with height, reaching a minimum of about -
90°C at the "mesopause".
29. ATMOSPHERE LAYERS IN DETAILS
The Thermosphere and Ionosphere: The thermosphere lies above the
mesopause, and is a region in which temperatures again increase with height. This
temperature increase is caused by the absorption of energetic ultraviolet and X-
Ray radiation from the sun.
The region of the atmosphere above about 80 km is also caused the "ionosphere",
since the energetic solar radiation knocks electrons off molecules and atoms,
turning them into "ions" with a positive charge.
The temperature of the thermosphere varies between night and day and between
the seasons, as do the numbers of ions and electrons which are present.
The Exosphere: The region above about 500 km is called the exosphere. It
contains mainly oxygen and hydrogen atoms, but there are so few of them that
they rarely collide - they follow "ballistic" trajectories under the influence of
gravity, and some of them escape right out into space.
The biosphere is the narrow zone of contact between the land, water and air. It is the
zone where life exists that makes this planet unique. The organisms in the biosphere
are commonly divided into:
• the plant kingdom
• the animal kingdom
The three domains of the earth interact with each other and affect each other in some
way or the other.
• Every living thing, every plant, every lake, and every desert is a part of it. It's
pretty massive and pretty amazing. This is the largest category of organization for
• It's different from the next level of ecological organization, the biome. The
biosphere can be divided into several biomes.
• These regions have specific climates, vegetation, animals, and adaptations
necessary to survive in them
31. WHERE DID THE BIOSPHERE ORIGINATE?
• The biosphere has existed for about 3.5 billion years.
• The biosphere’s earliest life-forms, called prokaryotes, survived without oxygen.
Ancient prokaryotes included single-celled organisms such as bacteria and
• Some prokaryotes developed a unique chemical process. They were able to use
sunlight to make simple sugars and oxygen out of water and carbon dioxide, a
process called photosynthesis.
• These photosynthetic organisms were so plentiful that they changed the biosphere.
• Over a long period of time, the atmosphere developed a mix of oxygen and other
gases that could sustain new forms of life.
32. WHERE DID THE BIOSPHERE ORIGINATE?
• The addition of oxygen to the biosphere allowed more complex life-forms to
evolve. Millions of different plants and other photosynthetic species developed.
• Animals, which consume plants (and other animals) evolved. Bacteria and other
organisms evolved to decompose, or break down, dead animals and plants.
• The biosphere benefits from this food web. The remains of dead plants and
animals release nutrients into the soil and ocean. These nutrients are re-absorbed
by growing plants. This exchange of food and energy makes the biosphere a self-
supporting and self-regulating system.
33. BIOSPHERE RESERVES
• People play an important part in maintaining the flow of energy in the biosphere.
• For example, in the atmosphere, oxygen levels decrease and carbon dioxide levels
increase when people clear forests or burn fossil fuels such as coal and oil.
• Oil spills and industrial wastes threaten life in the hydrosphere.
• The future of the biosphere will depend on how people interact with other living
things within the zone of life.
• In the early 1970s, the United Nations established a project called Man and the
Biosphere Programme (MAB), which promotes sustainable development.
• Currently, there are 563 biosphere reserves all over the world.
• The first biosphere reserve was established in Yangambi, Democratic Republic of
Congo. Yangambi, in the fertile Congo River Basin, has 32,000 species of trees
and such endemic species as forest elephants and red river hogs.
34. HOW DOES LIFE SUSTAIN ITSELF IN THE BIOSPHERE?
• Scientists believe that the increase of atmospheric oxygen led to the evolution of
the first forms of life.
• Energy is needed for the function that organisms perform, such as growth,
movement, waste removal and reproduction. It is the only requirement that living
organisms in the biosphere need apart from what is there in the four major
• The source of this energy comes from the sun. Plants convert the sun’s energy into
food and are very important to the biosphere.
35. WHAT PROCESSES OCCUR IN THE BIOSPHERE?
The organisms in the biosphere are constantly involved in one or more of the
following processes :
• Decomposition : The breakdown of complex molecules—molecules of which
dead organisms are composed – into simple nutrients that can be re-utilized by
• Energy : Power that can be used to perform work, such as solar energy.
• Nutrient cycle : The cycling of biologically important elements from one
molecular form to another and back to the original form.
• Photosynthesis : Process in which plants capture light energy from the sun and
use it to convert carbon dioxide and water into oxygen and organic molecules.
• Respiration : Chemical reaction between organic molecules and oxygen that
produces carbon dioxide, water, and energy.