Environmental Unit 1

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Unit- I Multidisciplinary Nature of Environmental Studies(Dr. Bharti Arora) 1 2Dr. Bharti Arora

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Atmosphere LithosphereHydrosphere Biosphere

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Why We Want to Study the Environment

Sciences?

Dr. Bharti Arora

Why We Want to Study the Environment Sciences?

We live in natural surrounding (forest, river, mountain, etc.). Resources: renewable (forest and water) and non-renewable (minerals and oil).

Due to increase in population these resources are getting depleted gradually.

There is a need to understand, make ourselves aware of our natural assets and get concerned about our environment and sustainable utilize the resources.

Scope of environmental studies is very wide and nearly covers some aspects of every major discipline (biology, chemistry, physics, geography, resource management, economy, etc.).

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Multidisciplinary Nature of Environmental Studies



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People in Environment

Indira Gandhi

As PM played a verysignificant role in thepreservation of Indias WildLife.

S.P.Godrej

Indias greatest supporter of

wild life conservation and

nature awareness programs.

Between 1975 and 1999,

received 10 awards for his

conservation activities, he was

awarded the Padmabhushan in

1999.

M S Swaminathan

Indias foremost

agricultural scientists.

Founded the MS

Swaminathan Research

Foundation in Chennai

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Madhav Gadgil

Well known ecologist in India

M.C.Mehta

Indias most famous environmental lawyer.

Anil Agarwal

A journalist

People in Environment20Dr. Bharti Arora

Medha Patkar

Social activist

Sunderlal Bahuguna

Chipko movement has become an internationally well-known example of a

highly successfully conservation action

program

And Many others

People in Environment21Dr. Bharti Arora

17th Century has been described as the

AGE OF FAITH

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18th Century is considered as the

AGE OF REASONING

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19th Century was

AGE OF PROGRESS

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20th Century was AGE OF STRESS

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Will 21st Century be

Age of Panic or Age of Peace?

You have to decide.26Dr. Bharti Arora

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Hydrosphere

The hydrosphere is often called the "water

sphere" as it includes all the earth's water

that is found in streams, lakes, the soil,

groundwater, and in the air.

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Earth: Blue Planet

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The Structure of Hydrosphere

Oceans96.5% of water is salt water and is found in the oceans.

Fresh waterthe remaining 3 percent is freshwater.

Fresh water distribution:

Ice: 1.762%

Groundwater: 1.7%

Surface Fresh Water: 0.014%

Atmosphere and soil: 0.002%

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Earth's Lithosphere

Out of known planet of solar system, earth is where life

exists, which requires appropriate temperature and food

for survival.

Structure of the Earth

The Earth is made up of 3 main layers:

Core

Mantle

Crust

Inner core

Outer core

Mantle

Crust

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The Crust This is where we live!

The Earths crust is made of:

Continental Crust

- thick (10-70km)

- buoyant (less dense

than oceanic crust)

- mostly old

Oceanic Crust

- thin (~7 km)

- dense (sinks under

continental crust)

- young35Dr. Bharti Arora

The Lithosphere

The lithosphere is the hard shell of the Earth, consisting of the crust and the topmost part of the upper mantle.

It is an average of 100km thick.

It contains the minerals, rocks and soils that humans have used for building materials, metals and agriculture. 36Dr. Bharti Arora

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Crust solid, relatively low density silicate rock

Mantle Semi fluid, denser, iron and magnesium bearing rocks

Core Liquid then solid iron and nickel with traces of heavier elements

What lies beneath the tectonic plates?

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Tectonic Plates

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Plate Tectonics

Plates are made of rigid lithosphere.

These pieces of the lithosphere that move around.

There are approximately 12 major and 8 minor plates that move in concert with each other.

Fit together like jigsaw puzzles

Float on top of mantle similar to ice cubes in a bowl of water.

This plate motion causes them to collide, pull apart, or scrape against each other.

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Divergent (plates move away from each other)

Convergent (the plates move towards each other)

Transform (the plates slide past each other)

Three types of plate boundary

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Plate tectonics explains:

1. Volcanoes tend to erupt at plate margins.

2. Earthquakes occur where plates grind against or over one other.

3. Mountain building occurs as one plate is pushed over another.

4. Seafloor spreading occurs where two oceanic plates pull apart.

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The atmosphere is a thin layer of air that protects the Earths

surface from extreme temperature and harmful sun rays.

Earth's Atmosphere

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Atmospheric Gases(Mixture of gases, solids, and liquids)

Nitrogen - 78%

Oxygen - 21%

Water Vapor 0 to 4%

Used for clouds and precipitation

Carbon Dioxide - .037%

Keeps Earth warm and is used by plants to make food

Argon - .93%

Traces of neon, helium, methane, krypton, xenon, hydrogen, and ozone

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Layers of the Atmosphere

and Temperature

The four layers of the

atmosphere include:

1. the troposphere, where

we live;

2. the stratosphere, which

contains the ozone layer;

3. the mesosphere, where

meteors burn; and

4. the thermosphere, where

satellites orbit Earth.

Troposphere The troposphere is the lowest layer of the atmosphere.

Extends to between 7 km (23,000 ft) at the poles and17 km (60,000 ft) at the equator, with some variation due to

weather factors.

Most of the air that makes up the atmosphere is found inthe troposphere.

Nearly all of the water vapor and dust particles in theatmosphere are in the troposphere. That is why

most clouds are found in this lowest layer, too.

Weather occurs in this layer.

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Most of the layers heat is from Earth and thustemperature decrease with height in this layer.

The troposphere is heated from below. Sunlight warmsthe ground or ocean, which in turn radiates the heat into

the air right above it. This warm air tends to rise. That

keeps the air in the troposphere "stirred up".

The top of the troposphere is quite cold. Thetemperature there is around -55 C (-64 F)! Air also

gets 'thinner' as you go higher up. That's why mountain

climbers sometimes need bottled oxygen to breathe.

The boundary between the top of the troposphere andthe stratosphere (the layer above it) is called the

tropopause.46Dr. Bharti Arora

StratosphereExtends from the troposphere's 7 to 17 km (23

- 60,000 ft) range to about 50 km (160,000 ft).

The stratosphere contains the ozone layer,which heats this layer as it absorbs energy from

incoming ultraviolet radiation from the Sun.

Temperatures rise as one moves upwardthrough the stratosphere. This is exactly the

opposite of the behavior in the troposphere in

which we live, where temperatures drop with

increasing altitude. Because of this temperature

stratification, there is little convection and

mixing in the stratosphere, so the layers of air

there are quite stable.47Dr. Bharti Arora

Many jet aircrafts fly in the stratosphere.

The boundary between the stratosphere and the mesosphereabove is called the stratopause.

The stratosphere is very dry; air there containslittle water vapor. Because of this, few clouds are found in this

layer; almost all clouds occur in the lower, more humid

troposphere.

Air is roughly a thousand times thinner at the top of thestratosphere than it is at sea level. Because of this, jet aircraft

and weather balloons reach their maximum operational altitudes

within the stratosphere.

Due to the lack of vertical convection in the stratosphere,materials that get into the stratosphere can stay there for long

times. Such is the case for the ozone-destroying chemicals called

CFCs (chlorofluorocarbons).

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MesosphereAs you get higher up in the mesosphere, the temperature getscolder. The top of the mesosphere is the coldest part of Earth's

atmosphere. The temperature there is around -90 C .

Extends from about 50 km (160,000 ft) to the range of 80 to 85 km(265 - 285,000 ft).

Temperature decreasing with height.

Meteors or rock fragments burn up in the mesosphere.

The mesopause is the boundary between the mesosphere and the thermosphere above it.

Scientists know less about the mesosphere.

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Thermosphere

from 80 85 km (265 - 285,000 ft) to 640+ km.

Temperature increasing with height. Temperature in the thermosphere can

reach 1,800C.

This is also where the space shuttle orbits the Earth!

The boundary between the thermosphere and the exosphere above it

is called the thermopause.

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Although the thermosphere is considered part of Earth'satmosphere, the air density is so low in this layer that most

of the thermosphere is what we normally think of as outer

space.

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

In the thermosphere and above, gas particles collide soinfrequently that the gases become somewhat separated.

Energetic ultraviolet and X-ray photons from the Sunalso break apart molecules in the thermosphere. In the

upper thermosphere, atomic oxygen (O), atomic

nitrogen (N), and helium (He) are the main components of

air.51Dr. Bharti Arora

Ionosphere located in the thermosphere and also in some parts of Mesophere & Exosphere

which contains free charged particles.

It is the part of the atmosphere that is ionized by solar radiation.

It plays an important part in atmospheric electricity.

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The exosphere begins at about 500 kilometers above Earth and

does not have a specific outer

limit.

Satellites orbit Earth in the exosphere.

The exosphere is on top of the thermosphere.

Exosphere

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Biosphere is the regions of the surface and atmosphere of the Earth or other planets where living organisms exist. So basically, it is where ever a living ORGANISM can live, be it sky, or ocean or land. They are all biosphere.

Biosphere

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Environmental Unit 1