THE OZONE LAYER AND ITS DEPLETION

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THE OZONE LAYER

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INDEX

TOPIC Pg no.Layers of the Atmosphere 4-5

The Sun’s Utraviolet Rays 6-8

The Ozone Layer 9

The atmosphere is divided into five layers. It is thickest near the surface and thins out with height until it eventually merges with space.

1) The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer.

2) Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun.

3) Meteors or rock fragments burn up in the mesosphere.

LAYERS OF THE ATMOSPHERE

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4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits.

5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.

Ozone layer

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The sun emits energy over a broad spectrum of wavelengths:

visible light that you see

infrared radiation that you feel as heat

ultraviolet (UV) radiation that you can’t see or feel.

UV radiation has a shorter wavelength and higher energy than visible light.

THE SUN’S ULTRAVIOLET RAYS

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It affects human health both positively and negatively.

Short exposure to UVB radiation generates vitamin D, but can also lead to sunburn depending on an individual’s skin type.

Fortunately for life on Earth, our atmosphere’s stratospheric ozone layer shields us from most UV radiation

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Damage to the ozone layer can cause the following:

Skin cancer

Cataracts

Suppression of the immune system

Premature aging of the skin

Since the benefits of sunlight cannot be separated from its damaging effects, it is important to understand the risks of overexposure, and take simple precautions to protect yourself.

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The ozone layer is a deep layer in the stratosphere, encircling the Earth, that has large amounts of ozone in it.

The layer shields the entire Earth from much of the harmful ultraviolet radiation that comes from the sun.

For nearly a billion years, ozone molecules in the atmosphere have protected life on Earth from the effects of ultraviolet rays.

THE OZONE LAYER

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THE OZONE LAYER DEPLETION

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INDEXTOPIC Pg no.

The Ozone Hole and Its Causes 12-13

Observations on Ozone LayerDepletion

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Observation 1 15

Observation 2 17

Misconceptions about the Ozone Layer Depletion

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Bibliography 19

THE OZONE HOLE AND ITS CAUSES

Recently, chlorofluorocarbons (CFCs) were used a lot in industry and elsewhere to keep things cold and to make foam and soaps.

Strong winds carry CFCs up into the stratosphere where UV radiation breaks them apart, releasing chlorine atoms.

Each chlorine atom can attack and break apart (destroy) as many as 100,000 ozone molecules during the time it is in the stratosphere.

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The chlorine from CFCs reduces (depletes) the amount of ozone in the stratosphere.

Other ozone-eating chemicals are pesticides such as methyl bromide, halons used in fire extinguishers, and methyl chloroform used in businesses.

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There are many observations on the ozone layer. The following are a few observations:

OBSERVATIONS ON OZONE LAYER DEPLETION

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Scientists did predict that ozone depletion should peak around year 2010.

As world-wide controls reduce the release of CFCs and other ozone-eating substances, nature will repair the ozone layer.

By year 2065 stratospheric ozone should return to the amount present in 1980.

Until then, we can expect higher levels of UV radiation at the Earth's surface.

We need to take care to avoid the bad health effects that could result from too much UV radiation.

OBSERVATION 1

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Most countries have seen the threats created by ozone depletion and agreed to a treaty called the Montreal Protocol.

This Protocol will help humans to stop making and using ozone-eating chemicals.

OBSERVATION 2

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MISCONCEPTIONS ABOUT THE OZONE LAYER DEPLETION

COMMON MISTAKE FACT

Global warming is caused by the ozone hole which was created by chemicals like CFC etc.

The ozone layer protects theEarth from the Sun’s harmful UV rays. Hole in the ozone layer has been caused by chemicals released by humans.

CFC’s are “too heavy” to reach the stratosphere.

CFC’s are commonly believed to be heavy. But atmosphere gases are not sorted by weight. The wind mixes the gases and they reach the atmosphere. 18

The ozone layer must be protected.

For this the use of CFC’s has to be stopped.

We must buy products that are labelled “ozone friendly” or “ CFC free”.

Substitutes for CFC’s should be used.

HCFC’s are substitutes for CFC’s.

Let us all take a step ahead and save the ozone layer.

PROTECTING THE OZONE LAYER

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http://epa.gov/sunwise1/kids/kids_ozone.html

http://www.epa.gov/sunwise/doc/uvradiation.html

http://en.wikipedia.org/wiki/Ozone_depletion

http://www.windows2universe.org/earth/Atmosphere/layers.html

http://www.google.com/imgres?q=ozone+layer&hl=en&biw=1360&bih=649&gbv=2&tbm=isch&tbnid=U_EYVGK2GX8xbM:&imgrefurl=http://www.okiu.ac.jp/Language/contest/02/12/ozone.htm&docid=M7

http://www.theozonehole.com/ozoneholehistory.htm

BIBLIOGRAPHY

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MADE BY: AAKANKSHA MADAN

SHREYA SINGHNIDA MEMON

RIYAA SOMANISAAMIYA SIDDIQUI

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