Transcript The Air Around You - Culver City Middle School

The Air Around You
Chapter 7.1
 Atmosphere
 The Earth has gases
all around. This layer
of gas surrounding the
earth is called the
atmosphere.
 What does the
atmosphere do
for us?
 Earth’s atmosphere makes
conditions on Earth suitable
for living things.
 Contains gases we need to
live
 Traps energy from the sun
and keeps the Earth Warm
enough for water to exist as
a liquid.
 Protects biotic factors from
radiation from the sun.
 Prevents earth from being hit
by most meteoroids.
 Composition 
of the

Atmosphere



Nitrogen 78%
Oxygen 21%
Argon 0.93%
Carbon Dioxide 0.038%
Water Vapor (varies)
N
O
A
C
7.3 Layers of the atmosphere
 Troposphere – Weather
pg. 269




Troposphere
Stratosphere
Mesosphere
Thermosphere
– Ionosphere
– Exosphere
–
–
–
–
–
–
Taste
Sweet
Melon
That
Is
Excellent!
occurs. Airplanes fly just
above the clouds
 Stratosphere – The Ozone
layer absorbs ultraviolet light
 Mesosphere – meteoroids
burn up here producing
meteor trails
 Thermosphere:
– Ionosphere – Aurora borealis
occurs here
– Exosphere- satellites orbit
Earth.
Mr. Lee - Layers of the Atmosphere rap
 Ozone Layer
The Ozone Layer is a layer of
O3 molecules that is found
in the stratosphere.
The ozone layer protects us
from harmful UV light from
the sun.
What is causing ozone
depletion?
 In 1978 the U. S. Government banned the use of certain
CFCs, and manufacturers of aerosol products had to find
other propellants. Some of the alternative propellants
include hydrochlorofluorocarbons (HCFCs),
hydrofluorocarbons (HFCs), and carbon dioxide. In 1987
an international treaty known as the Montreal Protocol on
Substances that Deplete the Ozone Layer decreed that
CFC use should be decreased. Two years later 93 nations
agreed to stop producing CFCs entirely and help poorer
nations make the transition to other chemistries.
 Now less than two percent of American-made aerosol cans
contain CFCs. Those that do contain CFCs mostly
dispense drugs, such as asthma inhalers. The other
chemical compounds that have been developed to replace
CFCs thus far are more expensive and less versatile. One
promising alternative propellant is Polygas, developed by
Scottish inventor Bernard D. Frutin. This mixture of carbon
dioxide and acetone is reportedly superior to other
propellants because it is more environmentally sound, less
flammable, and creates higher and more consistent
pressure.