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‏إظهار الرسائل ذات التسميات 1الدرس الاول. إظهار كافة الرسائل
‏إظهار الرسائل ذات التسميات 1الدرس الاول. إظهار كافة الرسائل

Lesson 1 of unite 2;The Atmospheric Layers

The Atmospheric Layers
Lesson objectives :

  • By the end of this lesson, the student must be able to:
1-Know the concept of atmospheric pressure.

2- Interpret the change of atmospheric pressure with changing height above sea level.

3- Understand the change of atmospheric pressure with changing height above sea level

4- Appreciate the importance of instruments that measure atmospheric pressure.

5-Mention the importance of altimeter.

6-Know atmospheric layers.

7- Mention the characteristics of atmospheric layers.

8-Compare among the characteristics of atmospheric layers.

8-Determine the importance of each layer of the atmosphere.

 Atmospheric pressure

  • The Earth is surrounded by a gas envelope that rotates  with it about its axis, and extends 1000 km above sea level. It is known as atmosphere

  • The weight of air column of an atmospheric height on a unite area is called air pressure or atmospheric  pressure.
  • It is measured in a unit called a bar. The bar equals
1000 millibar (mbar).
  • Normal atmospheric pressure at sea level equals 1013.25 millibar.

  •  In airplanes, an altimeter is used to determine the elevation of the navigation based on the atmospheric
    pressure at this level.



  • The possible day’s weather can be estimated directly with an instrument known as aneroid measure atmospheric pressure.


  • for more in formation about troposphere , please visit these link:

Atmospheric layers

 1-First layer : Troposphere


Characteristics and importance of the troposphere:

1-It extends 13 km above sea level to the tropopause.
As we go up, the temperature decreases by
a rate of 6.5 ºC per 1 km until it reaches the lowest
value of about (-60 ºC) at troposphere.

2-Atmospheric pressures decreases as we go higher,
where it reaches about 0.1 bar of the normal pressu re
at sea level.

3-It contains about 75% of the atmosphere mass.
This explains why all atmospheric phenomena like
the weather conditions ,and consequently up the climate climate, occurs in this layer and affects the
 activities of living organisms.

4-It contains about 99% of the atmospheric water vapor,which organize the temperature of earth.

  • for more in formation about troposphere , please visit these link:


2- Second layer: Stratosphere
Characteristics and importance of the stratosphere:

1-It extends from troposphere (13 km above sea level) to the stratosphere (50 km) with thickness of 37 km.

2-At the lower part, the temperature is constant and measure (– 60º C), then increases gradually until it
 reaches 0º C at the end of the layer. This is due to the absorption of ultraviolet radiation ( emitted from the
 Sun) by the ozone layer that is present in the upper
part of the layer.

3-The atmospheric pressure decreases on going higher where it reaches the smallest value ( .oo1 bar f the
normal pressure at sea level) at the
end of the layer.

4-It contains most of the atmospheric ozone which is
concentrated between 20 - 40 km above sea level.
The lower part does not contain clouds or suffer
from any weather disturbances. 

5-The air moves in this layer horizontally.
  •  for more in formation about troposphere , please visit these link:

 3-Third layer: Mesosphere
Characteristics and importance of the mesosphere:
 
1- It is extended from the stratopause (50 km above sea
level) to the mesopause (85 km) with thickness of
about 35 km.

2-Temperature decreases with height rate until
reaches (– 90º C) at its end.

3-This layer is much vacuumed as it contains only
a limited amount of helium and hydrogen gases.
Meteors are formed in this layer and burnt due to friction

  • for more in formation about troposphere , please visit these link:

 4-Fourth layer: Thermosphere


  •  Thermosphere is the fourth atmospheric layer. It means the heated layer as it is the hottest layer of the  atmosphere.


Characteristics and importance of the thermosphere :


1- It extends from the mesosphere to 675 km above sea level with a thickness of about 590 km.


2-Temperatures increase rapidly with going higher until it reaches about 1200º C.


3-Its upper part contains charged ions. The distribution of the charged ions extends until 700 km above sea
 level; in a part known as ionosphere.

A- Ionosphere plays an important role in wireless communication and broadcasting it reflects radio waves which is transmitted by radio stations

B.Ionosphere is surrounded by two magnetic belts known as Van Allen belts they are playing important roles in dispersing the harmful charged cosmic radiation away from the Earth. In the same time, they cause the Aurora phenomenon,





which appears as brightly colored light curtains at both the south and north polar

C.The atmosphere is inserted into the outer space via an area known as the Exosphere. 



 

where earth float and transmit weather condition information and TV programs Space channels use satellites to transmit media and commercial materials. Some of them is useful and acceptable. Others contradict morals and religion principles.

for more in formation about this layer , please visit these link:

for more in formation about this atomspheric layer , please visit these link:

for more in formation about this lesson , please visit these link:

                

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