Download Earth`s Atmosphere

Earth’s Atmosphere
 Why
is it so
important to
life on
earth?
OBJECTIVES:
1. describe the layers
of the atmosphere.
2. differentiate the
layers of the
atmosphere based
on variation of
temperature.
3. explain the
significance of the
layers and the
boundaries
between them.
The Moon
The Planet Earth
What
are
the
layers
of moon
theof
earth’s
What
islayer
the of
importance
the
Is
there any
air on the
that
can
Can
I
make
fire
while
on
the
moon?
Is
there
oxygen
on
the
moon?
protect youatmosphere?
from the sun’s direct light?
atmosphere?
Importance of the Atmosphere

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Creates suitable living conditions for life
Living things needs oxygen, warmth and
liquid water
Traps solar energy warm enough for
water to exist as a liquid
Protects against solar radiation
Helps prevent meteor strikes from space
If Earth Had No Atmosphere


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No lakes or oceans
No Sounds
No Clouds
No Red Sunsets
Extremely Cold Nights & Hot Days
We could only survive a few minutes
Fun Fact: Any more than 21% oxygen and
we would burst into flames from the
flammability of oxygen.
The Atmosphere


Earth’s atmosphere is
a layer of gases
surrounding the planet.
The atmosphere
protects and supports
life.
What's in Earth's atmosphere?

Earth’s atmosphere is made of a mixture of
gases called air.

78% Nitrogen

21% Oxygen

1% Trace Gases
Nitrogen Cycle


Nitrogen is important
to protein which is
found in the body
tissues of all living
things.
Nitrogen is cycled
through the soil and
into plants and finally
when living things die
and decay.
The story of Earth’s
Atmosphere

Earth’s unique
atmosphere exists
because our planet
has the right balance
between mass and
distance from the
Sun.
Density


Air consists of atoms and molecules,
which have mass, so…Air Has Mass!
The amount of mass in a given volume of
is Density.
Density=Mass/Volume
 More molecules in a space mean more
density
 Less molecules in a space mean less density
Air Pressure



PRESSURE is the force pushing on an
area or surface. “force per unit area”
The weight of the atmosphere exerts a
force on surfaces
AIR PRESSURE is the result of the weight
of a column of air pushing down on an
area.
Pressure in the atmosphere

The gas molecules
closest to Earth’s
surface are packed
together very closely.

This means pressure
is lower the higher up
you go into the
atmosphere.
Pressure changes with
Altitude
Pressure in the atmosphere

At sea level, the weight of
the column of air above a
person is about 9,800
Newtons (2,200lbs)

This is equal to the weight
of a small car.

Why aren’t we crushed by
this pressure?
Why aren’t we crushed?

Air pressure doesn’t crush you or anything
else around you because the molecules in
air push in all directions-down, up and
sideways.
Measuring Pressure


A barometer is an
instrument that
measures atmospheric
pressure.
Long ago, mercury
barometers were used.
Measuring Pressure
Since mercury is a
poisonous liquid,
aneroid barometers
are used today.
Earth’s atmosphere is made
up of different layers…
Layers of the Earth’s Atmosphere
 troposphere
 stratosphere
 mesosphere
 thermosphere
> ionosphere
> exosphere
Why is the atmosphere
divided into different layers?

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

Any guesses?
The atmosphere is divided into
four different layers because
the atmosphere is not uniform,
its properties change with
altitude.
Two properties change with
altitude, the AIR PRESSURE
and the AIR TEMPERATURE
Lets look at each layer
individually.
The first layer of the atmosphere
is the…
TROPOSPHERE
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Lowest and thinnest layer
The troposphere goes from 0km to 11km.
All weather happens in the troposphere.
90% of the atmosphere’s total mass is in this
layer
The temperature drops as the altitude increases.
Tropopause

Boundary between the
troposphere, and the
next layer (the
Stratosphere) is called
the tropopause

Temperature is
constant with altitude

From 11-20 km
STRATOSPHERE
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Extends from 20 km to 50 km
Less dense (less water vapor)
Temperature increases with
altitude
 TEMPERATURE
INVERSION
Almost no weather
occurrence
Contains the ozone layer
Jets fly in this layer
Stratopause

Boundary between the
stratosphere and the
next layer (the
mesosphere) is called
the stratopause

Temperature is
constant with altitude

From 50-55 km
Ozone Layer

A gaseous layer in
the upper
stratosphere that
protects the earth
from harmful
ultraviolet radiation

O3 = 3 oxygen atoms
in an ozone molecule
Ozone
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Forms naturally in the stratosphere
It is naturally destroyed by U.V. Radiation
and creates more O2 (oxygen)
O3 + U.V.  O2 + O
CFC’s are chlorofluorocarbons-pollutants in
our atmosphere (chlorine, fluorine, carbon)
Chlorine atoms (Cl) destroy 100,000 O3
molecules before combining with other atoms
The third layer of the atmosphere is
the…MESOSPHERE

From 50km to 90km.

temperature decreases as
altitude increases

The mesosphere is the
coldest layer of the
atmosphere. (-90 degrees)

Meteors burn up in this layer.
MESOSPHERE

Very low air pressure as
99% of atmosphere is
below it.

Gases are less dense in
this layer and absorb very
little UV radiation.

Fun Fact: Low air
pressure would make
your blood boil from the
U.V. radiation.
Mesopause

Boundary between the
mesosphere and the
next layer (the
thermosphere) is called
the mesopause

Temperature is
constant with altitude

At about 85-90 km
THERMOSPHERE

From 90km to outer space

temperature increases with
increasing altitude
 Temperature Inversion

Hot Layer-Temperature can go
as high as 1,500 °C

Air molecules are so far apart
so the solar energy that is
absorbed increases the
temperature more.
Thermosphere Division

Divided is divided into 2 Layers:

IONOSPHERE

EXOSPHERE
IONOSPHERE

Layer of electrically charged
particles called “ions”

Radio waves will bounce off
charged particles (ions) back
to earth
Auroras or “Northern Lights”

Particles from the sun enter
the atmosphere and strike
atoms causing them to glow
EXOSPHERE
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Uppermost part of
thermosphere
The exosphere is the
outermost layer of the
atmosphere.
The temperature in the
exosphere increases with
altitude.
Satellites and the Space
Shtuttle orbit earth in the
exosphere.
Atoms and molecules can
escape to space
THERMOSPHERE
MESOSPHERE
STRATOSPHERE
TROPOSPHERE
Global Warming
 An
increase in Earth’s average
surface temperature caused by
an increase in greenhouse gases.
 Caused
by Greenhouse Effect
The Greenhouse Effect

The trapping of heat by gases in the
atmosphere

Occurs naturally and makes the
surface of earth warm enough to
support life.
 This
is a good thing!
Greenhouse Gases
Greenhouse gases
> carbon dioxide
> sulfur dioxide
> ozone
> CFCs
> water vapor
Controversy

When people talk about Global Warming
in a negative way, it refers to the planet’s
warming up faster than natural due to
pollution being put into the atmosphere
and causing an increase of the
greenhouse effect as well.

Controversy over whether or not our
pollution has caused an increase in global
warming.
Effects of Greenhouse Gas Pollution

Global warming
> ice in polar caps will begin to melt
> water in the ocean expands
> flooding in lowlands
and coastal areas
> changes in weather
patterns