chapter 4: atmosphere061851f72b23d802adaa-d56582058559818728a814bdd94ad99a.r54… · photosynthesis...

Chapter 4: Atmosphere

Table of Contents

Section 1: Earth's Atmosphere

Focus: Definition of atmosphere

The composition of the atmosphere

The layers of the atmosphere

The importance of the atmosphere

The greenhouse effect and the ozone layer

• What is atmosphere?

• It is a thin layer of gas that forms a

protective layer around the planet

The importance of the

atmosphere

1- contains the oxygen that we need to

survive

2- it is a radiation shield that protects us

3- It keeps us warm- absorbs some of the

heat from the sun preventing all of it from

radiating out into space

Other importances

4- protects us from objects falling from

space – these pieces of rock burn out due

to the friction of the air.

5- has Carbon Dioxide necessary for

photosynthesis and production of

oxygen

6- sound waves travel through air, allowing

us to listen to one another

7- air allows flight to happen

Makeup of the Atmosphere

• Earth's atmosphere is a mixture of gases, solids, and liquids that surrounds the planet.

Also found:

Water

Droplets,

Sand,

Salt,

Pollen,

Dust

Millions of years ago, the atmosphere was rich in Nitrogen and Carbon Dioxide

the amount of oxygen increased slowly mostly due to the photosynthesis from algae life was mostly under water

more oxygen was formed Ozone layer appeared allowing life out of the water, by protecting life from damaging sun rays

More oxygen was formed, the atmosphere kept on changing and is still changing mostly due to man intervention

The development of the Earth’s atmosphere

Layers of the atmosphere

• Using graph paper and the book, draw the

layers of the atmosphere proportionally

on a graph. (Consider the size of each

layer – see figure 4 page 92). Include the

Ionosphere ( see page 93)

• Include any important information you find

in the book about each one of the layers

• Draw arrows to show what happens with

the atmospheric pressure and temperature

when you move up the layers.

• What is air made of ?????

Atoms Matter Mass Weight

Does air have weight?

What do you feel when you have something heavy

on your lap?

Pressure

Demo:

• 2 balloons and a hanger

1) What is the difference between both

balls?

2) Explain why the inflated ball pulls the

hanger downwards.

3) Infer based on what you saw whether

air has mass.

4) Turn in

5) Let’s weight the balloons.

What do you feel when you have something heavy

on your lap?

Pressure

Atmospheric Pressure

• We understood by the hanger demo, that atmospheric gases have mass.

• We have lots of gases on top of us, lots of atoms and molecules

• These atoms and molecules will exert a force called Atmospheric Pressure

Mini Lab

• Observing Air Pressure

• Follow the instructions

• CAUTION: work on top of the empty

container to avoid major water spills

• Discussion: what do you think is

happening?

**Mini Lab: Observing Air Pressure

*This experiment shows us that air has mass capable

of exerting pressure .

The force of gravity on the water applying pressure

on the index card is weaker than the force applied by

the air.

In other words, the air is pushing up on the card

more than the water is pushing down on it.

The air pressure is holding the paper snug against the

cup.

**Mini Lab: Observing Air Pressure

answer the questions below

1) There are 2 forces acting on the index

card. Which are these forces? Draw the

cup and the forces. Represent the forces

with arrows and show which one is

bigger.

2) Why is that the water does not fall from

the cup?

3) Turn in.

**Definition- copy

Atmospheric Pressure

Pressure caused by the weight of the atmosphere.

At sea level you have maximum atmospheric

pressure but it reduces with increasing altitude

because the molecules of the gases are further

apart.

Read page 94 – Applying Science

Temperature in Atmospheric

layers

• Text and Graph page 95 – read

• Various layers have different

temperatures: because they have a

different gas composition and will absorb

the heat from the sun in different

amounts

**Fossil fuel: nonrenewable energy

resources

Ex: coal, oil, natural gas,

Fossil fuels are formed in the earth from

dead plants or animals, millions of

years ago.

• The composition of the atmosphere is changing in small but important ways.

• The constant burning of fossil fuels is increasing the levels of certain gases in the atmosphere

•these gases are called greenhouse gases

• Greenhouse effect: heat-trapping

feature of the atmosphere due to the

gases present in the atmosphere.

• These gases are: methane, carbon

dioxide, water vapor,

chlorofluorocarbons

• This is usually good because help us

keep warm and guarantees life on earth.

BUT: The

increased

amount of

greenhouse gases

in the

atmosphere

accentuates the

greenhouse effect,

affecting the climate

certain

areas.

( temporary

increase in local

temperatures)

**Global Warming –

definition

• Global warming is the unusually rapid

increase in Earth’s average surface

temperature over the past century.

Global Warming

• Throughout history, Earth has warmed

and cooled several times.

• Nowadays, the climatic warming is

occurring much faster then in the past

**Causes of Global Warming

Natural causes:

• Variations in Sun's energy

• Subtle shifts in the Sun’s orbit – if the

Sun its closer to the Earth, we will

receive an increased amount of heat

• Fluctuation in ocean currents

• Volcanic eruptions

Man – related Causes of Global

Warming

• Global warming is primarily happening

due to the greenhouse gases released

by people burning fossil fuels.

• Methane, water vapor, carbon dioxide,

fluorinated gases such as CFC

(chlorofluorocarbons) – increase the

greenhouse effect and the amount of

heat trapped on earth’s surface

Effects of an increased Greenhouse

Effect

• Not only the increase in Earth

temperature, but also:

• Modification of rainfall patterns

• Amplification of coastal erosion

• Melting of ice caps and glaciers

All this affects the living organisms in the

planet

You tube video

• Global Warming Facts - NASA Global

Warming

• https://www.youtube.com/watch?v=ROZ

JmX73FF4

The Ozone Layer

• Located in the stratosphere

• Ozone is made of 3 atoms of oxygen.

Your life depends on Ozone

• The ozone layer shields you from the Sun's harmful energy.

• Ozone absorbs most of the ultraviolet radiation that enters the atmosphere.

The effect of CFCs

• Evidence exists that some air pollutants such as CFCs are destroying the ozone layer.

Chlorofluorocarbons (CFCs): are chemical compounds used in some refrigerators, air conditioners, aerosol sprays and in the production of some foam packaging.

Chlorofluorocarbon molecules destroy ozone and the products do not absorb UV rays from the Sun, exposing the Earth to more radiation

The Ozone Hole

• The destruction of ozone molecules by CFCs seems to cause a seasonal reduction in ozone over polar regions called the ozone hole or ozone depletion.

• The fluctuation of the levels of Ozone over the polar regions follows a pattern, increasing and decreasing during the year.

Oct. 2014 Ozone hole Nasa

update

The 2014 Ozone hole is comparable to

the size of the holes in 2010, 2012, 2013.

It is a little bigger than 2013.

It did not reach the biggest sizes that were

observed during the period of 1998- 2006.

Oct. 2014 Ozone hole Nasa

update

One factor that could be influencing the

occurrence of smaller ozone holes in

Antarctica:

- Decline of CFC in the atmosphere. The

level of CFC declined 9% since 2000

Chapter Review page 112: 1, 3, 5, 6, 8, 9,

10, 11, 17,20, 22

Workbook page 11

Section 1 Review page 97 1 through 3

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