Post on 25-Jul-2020
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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