UNIT 2
LESSON 1
1
Represented By : Sahar hussen
The Atmospheric Layers
CONTENTS :
1.
2.
4.
Represented By : Sahar Alhoussien
3.
The Atmospheric Envelope .
The Atmospheric Pressure & Measuring .
The Atmospheric Pressure Maps & Isobars .
Layers Of The Atmospheric Envelope .
Troposphere .
 Stratosphere .
 Mesosphere .
 Thermosphere .

5.
Exosphere Layer .
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THE ATMOSPHERIC ENVELOPE (AIR) :

The atmospheric envelope is responsible for what`s
known as ATMOSPHERIC PRESSURE .
Represented By : Sahar Alhoussien
3
ABOUT ATMOSPHERIC PRESSURE :



Represented By : Sahar Alhoussien

it`s measured by : Bar = 1000 mb .
The normal atmospheric pressure at sea level is :1013.25 mb .
For measuring the atmospheric pressure , we use tools (
instruments ) called : Barometers .
Types of Barometers :
Aneroid
• Used to determine the possible weather conditions
Altimeter
• Used by pilots
• Used to measure elevation from sea level depending on measured atmospheric
pressure .
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ABOUT ATMOSPHERIC PRESSURE :


Density of air
by
elevation above sea level &
that`s due to
of air column .
in length
Relationship
between altitude
of person above
sea level
&atmospheric
pressure
Represented By : Sahar Alhoussien

Its value differs from one
place to another , mainly
due to change of height
from sea level .
50% of atmospheric air mass
found in area from sea level
up to 3 Km height ..
90% atmospheric air mass
found at height up to 16 Km
above sea level
10
Height A.S.L (Km)

8
6
4
2
0
0
2
4
Pressure (mb)
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ATMOSPHERIC PRESSURE MAPS
They`re maps showing distribution of similar areas
depending on atmospheric pressure records , in which:
They`re points of equal A.Pressure
Represented By : Sahar Alhoussien
The Centre of low A.pressure represented at A.P.Maps ,by : L
The Centre of highA.pressure represented at A.P.Maps ,by : H
Winds move from high A.pressure to low A.pressure
If we connesct points os equal atm.pressure together by curved
lines, we`ll get what`s known as :Isobars
ISOBARS
They`re curved lines joining the points of equal
areas of Atm.pressure at A.pressure maps .
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Slides showing :
ISOBARS & ATMOSPHERIC PRESSURE MAPS
Represented By : Sahar Alhoussien
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ILLUSTRATION TO ISOBARS & PRESSURE MAPS
IN EGYPT
AREA
Higher than sea
level
Lower than sea level
examples
• Mokattam Hill
• El Haram Hill
• Sinai Peninsula
•
•
•
•
characteristics
Rocky area from lime
stones
Lower than sea level
Advantage
• Clean air
• Far from crowdness
Suitable for life in middle
of deserts
disadvantage
Roads difficult for
going up & down
As these areas lower than
sea level ,resulting in
Affect building designs
Formation of salts
depositions affecting
agriculture .
Represented By : Sahar Alhoussien
Wadi elnatroun
Siwa oasis
Kattara oasis
Elowainat oasis
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THE ATMOSPHERIC LAYERS
Represented By : Sahar Alhoussien
 The atmospheric envelope
classified into 4 main layers,
which are :I. TROPOSPHERE .
II. STRATOSPHERE .
III. MESOSPHERE .
IV. THERMOSPHERE .
This classification is mainly due
to 2 main factors , which are :I. Change in temperature .
II. Change in atmospheric pressure

 Between every 2 successive layers,
there`s an area with constant
temprature & these areas are :
I. Tropopause : bet.trposphere &
stratosphere .
II. Stratopause : bet.stratophere
&mesosphere .
III. Mesopause:bet.mesosphere
&thermosphere
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Slide showing :
Layers of atmosphere
Represented By : Sahar Alhoussien
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P.O.C
TROPOSPHERE
STRATOSPHERE
MESOSPHERE
THERMOSPHERE
POSITION
1st
2nd
3rd
4th
OTHER
NAMES
Disturbed layer
Ozonic layer
Coldest layer
RARIFIED
LAYER
• Cause
temp.decrease
s from zero⁰C
till reaches -90⁰C
.
1. Thermal layer
2. Ionic layer
35 Km
(extends from 50
Km till 85 Km
A.S.L)
590 Km
(extends from85
Km till 675 Km
A.S.L)
•
Cause all
weather
changes
occur in it .
•
Cause most of
ozone layer
present at
height from
20-40 Km .
thickness
Ava.13 Km
(8 Km above 2
poles &18 Km at
equator )
37 Km
(extends from 13
Km till 50 Km
A.S.L)
Temperatur
e
Decreases in
regular rate of
6.5⁰C/1 Km height
till reaches -60⁰C
Increases from
Decreases from
-60⁰C at lower part zero⁰C ,till reaches
till reaches zero⁰C at -90⁰C
top
1. Cause
temp.increase
till reaches
1200⁰C .
2. Cause the
upper part
contains
charged ions
till height of
700 Km .
Increases till
reaches 1200⁰C
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TROPOSPHERE
STRATOSPHERE
MESOSPHERE
pressur
e
As we go up,it
decreases till
becomes
100mb (0.1
bar)
As we go up, it
decreases till
becomes 1
mb(0.001 bar)
As we go up,it
decreases till
becomes 0.01
mb (0.00001
bar)
Air
moveme
nt
Vertically,
resulting in
moving of hot air
of low density
upwards & cold
air of high
density will move
downwards
Horizontally,
resulting in
preference of
pilots to fly their
planes in this
layer .
Characte 1. 75% of
1. Most of ozone
ristics
atm.air mass,
gas at height
(it
resulting in
20-40 Km
contains)
occurrence of
,resulting in
all
increases
atmospheric
temp. due to
phenomena
absorption of
as rains,
U.V radiation
clouds.
from sun .
1. Limited qty
of1H & 2He
only , that
why this
layer is
highly
rarified
layer .
THERMOSPHERE
Represented By : Sahar Alhoussien
P.O.C
1. Upper part
contains charged
ions, which
extends up to
height of 700 Km
A.S.L ,resulting
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in :
TROPOSPHERE
STRATOSPHERE
Character
istics
2. 99% of
2. Lower part
atm.water
doesn`t
vapour ,
contain any
resulting in
clouds or no
organization
weather
of earth
disturbances ,
temperature
resulting in
.
preference of
pilots to fly
their planes
in this layer .
MESOSPHERE
THERMOSPHERE
2. Friction
occurs
between air
molecules
and
celestial
rocky
masses
,resulting in
burning of
these
masses &
that`s lead
to :
 Formation of
luminous
meteors
 Protection of
earth from
rocky
masses
 Naming this
layer :
Ionosphere
 Occurrence of
Aurora
Phenomena ;
due to presence
of Van-Allen
belts .
Represented By : Sahar Alhoussien
P.O.C
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IONOSPHERE
It`s Thermosphere layer ,which contains charged ions
& has a great importance in wireless communications .
Ionosphere is imp. for wireless communication ??
Cause it reflects radio waves transmitted by
radio stations .
• It surrounded by 2 magnetic belts ,which have great effect ??
Cause these 2 magnetic belts satter the harmful
charged cosmic radiation ,away from earth , resulting in
occurance of : Aurora Phenomenum .
•
They`re 2 magnetic belts surrounding ionosphere &
scatter the harmful charged cosmic radiations.
AURORA PHENONENUM
It`s a phenomenon ,in which bright colored curtains
appear at 2 poles of earth .
Represented By : Sahar Alhoussien
VAN ALLEN BELTS
14
Slides showing :VAN ALLEN BELTS &
their rotation around
axis of earth
Represented By : Sahar Alhoussien
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Slides showing :
Aurora phenomenon
Represented By : Sahar Alhoussien
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EXOSPHERE :-
Represented By : Sahar Alhoussien
It`s region in which the atmospheric envelope inserted
with the outer space & satellites with cameras &
telescopes orbit around earth in this region & these
instruments used to transmit the weather condition
information & also T.V programs .
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