Erosion of Ozone Layer Erosion of Ozone layer

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Erosion of Ozone Layer

Erosion of Ozone Layer

Erosion of Ozone layer

Erosion of Ozone layer

Position of ozone layer : Ozone layer is mainly locate at height 20: 40

Position of ozone layer : Ozone layer is mainly locate at height 20: 40 Km above sea level in the lower part of stratosphere layer.

Why ? Because it is the first layer of atmospheric envelope which faces ultraviolet

Why ? Because it is the first layer of atmospheric envelope which faces ultraviolet radiations emitted from the sun, and also it contains suitable amount of oxygen gas.

Structure of Ozone layer : Ozone layer is composed of Ozone gas (O 3)

Structure of Ozone layer : Ozone layer is composed of Ozone gas (O 3) which consists of three oxygen atoms.

How ? When ultraviolet rays pass from oxygen molecule it break the covalent bond

How ? When ultraviolet rays pass from oxygen molecule it break the covalent bond and become one atom then it combine with anther molecule to make (O 3) molecule.

Ultraviolet rays UV O UV 2 O+O

Ultraviolet rays UV O UV 2 O+O

O+ O 2 O 3

O+ O 2 O 3

Thickness of Ozone The English scientist DOBSON layer postulated that the thickness of the

Thickness of Ozone The English scientist DOBSON layer postulated that the thickness of the Ozone layer is compressed into 3 mm. Only if it were under the normal pressure and 0 C temperature (STP).

The scientists took “DOBSON” as a measuring unit of degree for Ozone layer (100

The scientists took “DOBSON” as a measuring unit of degree for Ozone layer (100 DOBSON unit (DU) is defined as 1 mm. Thickness) so The thickness of Ozone layer=300 DU.

The importance of Ozone layer: There are three types of UV rays that differ

The importance of Ozone layer: There are three types of UV rays that differ in wavelength and effect :

Types of UV rays Near UV Rays (UV-A) Medium UV Rays (UV-B) Far UV

Types of UV rays Near UV Rays (UV-A) Medium UV Rays (UV-B) Far UV Rays (UV-C)

Living organisms Harmful effects Human : • Increase the rate of skin cancer •

Living organisms Harmful effects Human : • Increase the rate of skin cancer • cataract • Spoil eggs Amphibians : Marine organisms : • Death of plankton which is the main nutrient of small marine creature. Terrestrial plants : • Upset the photosynthesis process

Erosion in September Since 1978, scientists have noticed that !there was erosion in Ozone

Erosion in September Since 1978, scientists have noticed that !there was erosion in Ozone layer above the South pole , and it increase in September : Why ?

Because all pollutants assemble as black cloud and are pushed by wind towards south

Because all pollutants assemble as black cloud and are pushed by wind towards south pole making Ozone depletions increase from year to year.

Pollutant of Ozone layer : 1. 2. 3. 4. Chlorofluorocarbon (CFC). Methyl bromide gas.

Pollutant of Ozone layer : 1. 2. 3. 4. Chlorofluorocarbon (CFC). Methyl bromide gas. Halons. Nitrogen oxides.

Chlorofluorocarbon They are compounds known as (CFC) Freon, which used in: - Cooling substance

Chlorofluorocarbon They are compounds known as (CFC) Freon, which used in: - Cooling substance in air condition sets. - propellant substance in aerosols. - flating substance in making foam backing. - solvent substance for cleaning electric circuits slides.

Methyl bromide gas : It is used as an insecticide to preserve stored agricultural

Methyl bromide gas : It is used as an insecticide to preserve stored agricultural crops.

Halons: They are used in fire extinguishers.

Halons: They are used in fire extinguishers.

Nitrogen oxides: They are produced from the burning fuel of ultrasound planes (Concord).

Nitrogen oxides: They are produced from the burning fuel of ultrasound planes (Concord).

The effect of (CFC) compounds on Ozone layer: CFC compounds erode ozone layer in

The effect of (CFC) compounds on Ozone layer: CFC compounds erode ozone layer in three steps as the following:

The first step: CFCl 3 UV CFCl 2 + Cl

The first step: CFCl 3 UV CFCl 2 + Cl

The second step : Cl + O 3 O + Cl. O 2

The second step : Cl + O 3 O + Cl. O 2

The third step: Cl. O + O 3 2 O 2 + Cl

The third step: Cl. O + O 3 2 O 2 + Cl

Protecting the Ozone layer: - An international conference was held in “CANADA" in 16

Protecting the Ozone layer: - An international conference was held in “CANADA" in 16 -09 -1987 to discuss how to protect Ozone layer and take all suitable measures to solve s problem.

- They reached a group recommendations called “MONTEREAL PROTOCOL” where it is signed by

- They reached a group recommendations called “MONTEREAL PROTOCOL” where it is signed by 191 nations:

Some of these recommendations: • Using of chlorofluorocarbon compounds must be reduced and find

Some of these recommendations: • Using of chlorofluorocarbon compounds must be reduced and find safer alternatives. • Stop producing concord planes as their exhausts effect the Ozone layer.

In 1990, Montreal Protocol in London has been modified in a way that all

In 1990, Montreal Protocol in London has been modified in a way that all nations must ban: • Production or handing CFC compounds otherwise they will be allowed to export their goods.

Amount of production In In 1989 1990 1991 1992 1993 1994 1995 1996 about

Amount of production In In 1989 1990 1991 1992 1993 1994 1995 1996 about about less than 1010 m. t 700 m. t 600 m. t 500 m. t 400 m. t 200 m. t

The ministry of education Books

The ministry of education Books

Rania Ramadan A. Made by: E-mail: rramadan 78@yahoo. com

Rania Ramadan A. Made by: E-mail: rramadan 78@yahoo. com