Download Unit 3 THE EARTH`S ATMOSPHERE

UNIT 3: The Earth’s atmosphere
What do you remember?
• What atmospheric phenomena do you know?
• Air is a mixture of gases. Which are the most
abundant?
• Is the composition of air the same at sea level as
at the top of a very high mountain?
1. What do we know about the atmosphere?
The atmosphere is made up of gases in different proportions. Nitrogen and oxygen are the most abundant. The
atmosphere was very different 4600 years ago.
The primitive atmosphere was made up of water vapour, carbon dioxide,
nitrogen, hydrogen, ammonia, methane and other oxides, but no oxygen.
The first living beings (bacteria), produced oxygen by photosynthesis.
Molecules formed when chemical reactions took place between some gases.
These molecules fell to Earth with rain.
The present atmosphere is made up of 78 % nitrogen, 21% oxygen, 1%
carbon dioxide, water vapour, and other gases, such as argon.
Much later, the ozone layer was formed from oxygen. The ozone layer
protects life from harmful radiation from the Sun.
Composition of the air
1st. What are the five principal components of air? For each one indicate:
a) Its proportion
b) Its origin
c) If it has a role in an important process.
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The layers of the atmosphere
There are four layers. The Earth’s atmosphere is about 800 km high and held in place by the Earth’s gravity.
The separation in layers is caused by variation in temperature with respect to altitude.
Ionosphere. The highest and the thickest layer. Its
temperature increases to 1000 ºC due to X-rays and
gamma rays from the sun. Comets appear here.
Mesosphere. About 40 km thick. It contains clouds of
ice and dust.
Stratosphere. About 30 km thick. There is an
increase in temperature from -70 ºC at its lower limit
to 0 ºC at its higher limit.The ozone layer is here.
Troposphere. Very thin, but contains 80% of the total
mass of the atmosphere. This is where
meteorological phenomena occur.
2nd. Copy and complete with information about the layers in the Earth’s atmosphere.
Approximate thickness
Description of the layer
Troposphere
Stratosphere
Mesosphere
Ionosphere
2. What makes up the weather?
Weather describes the state of atmospheric conditions at a certain place, over a short period of time. Weather
conditions include:
Humidity. The concentration of water vapour in the atmosphere.
Clouds. Formed when rising air cools.
Precipitation. Water that falls to the ground: rain, snow and hail.
Temperature. How hot or cold the air is.
Wind. Movements of air.
Atmospheric pressure
Air has weight. The pressure it exerts on a surface is called atmospheric pressure. It is caused by gravity, and
is measured in millibars (mb).
th
In the 17 century, the Italian scientist, Torricelli, proved that atmospheric pressure is higher than at the top of a
mountain.
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The density of air on the Earth’s surface is about 1 kg/m . This means that 1 m weighs 1 kg. The higher the
altitude, the lower the density of air.
Predicting the weather
Air moves from high pressure areas to low pressure areas. This enables weather forecasters to predict the
weather.
Air moves because the Sun heats it. Hot air rises and the colder surrounding air moves in to take its place.
Low pressure area. Air moves from the sea towards a land mass. It brings humidity with it. Clouds
form and precipitations occur.
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High pressure area. Air moves from a land mass towards the sea. There are no clouds and the sun
shines.
On weather maps, lines called isobars
connect points with the same atmospheric
pressure. Look at this example.
H = high pressure L = low pressure
The rotation of the Earth also makes air move in spirals.
3rd. Look at the table. It shows the atmospheric pressure at different times.
Time
12:00
14:00
16:00
18:00
Atmospheric
Pressure
1020 mb
1016 mb
1010 mb
1007 mb
a) Is the atmospheric pressure increasing or decreasing?
b) Is there a possibility of high pressure or low pressure?
c) Will there be a high or low chance of clouds?
3. What factors affect climate?
Climate describes the characteristic pattern of weather in an area, over a long period of time. Factors affecting
climate are:
Latitude. How far north or south a place is from the Equator. At the Equator, solar energy is
concentrated and causes high temperatures. Towards the north and south, solar energy is more
spread out and causes cold temperatures.
Altitude. The height above sea level. The higher a place is, the colder it will be.
Distance from the sea.
-
Sea water heats up slowly and cools down slowly. In winter the sea releases heat, keeping
coastal areas warmer.
-
Land heats up quickly and cools down quickly. In summer, cold sea keeps coastal areas
cooler.
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Ocean currents.
-
Warm ocean currents flow up from the tropics to the poles and warm up surrounding areas,
especially in winter.
-
Cold ocean currents can lower temperatures in an area.
Coastal areas have milder weather than inland areas.
Clouds and precipitation
•
Rain occurs when condensation makes large, heavy droplets which fall to Earth. Snow and hail occur
when the water vapour in the air freezes.
•
Clouds form when rising air cools. Some of the water vapour molecules in the air condense to form cloud
droplets or ice crystals.
There are basic types of clouds: cirrus, cumulus and stratus. There are many variations of these.
Cirrus. High, thin clouds. These
form above 6000 m. They normally
mean fair weather.
Cumulus. Like cotton wool. They
form at about 1000 m. They can
develop into cumulonimbus:
thunder clouds.
Stratus clouds. Low, horizontal
clouds. These normally cover most
of the sky. Usually no precipitation
falls.
4th.What will the weather probably be like if you are looking at cirrus clouds? And if you are looking at
cumulonimbus clouds?
4. What is meteorology?
Meteorology is the study of different atmospheric variables to make weather predictions. Meteorologists collect
information about temperature, precipitation, wind, the humidity of the air, atmospheric pressure and clouds.
Meteostat photo
Map with weather simbols
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The most important meteorological instruments
A thermometer measures temperatura.
A barometer measures atmospheric
pressure.
A rain gauge/ pluviometer measures the
amount of rainfall per square metre.
A hygrometer measures the humidity in the
air.
An anemometer measures wind speed.
A weather vane shows the direction the
wind is coming from.
5th. You hear this report on the radio:
Wind speeds were 95 kilometres an hour and 200 litres of rain fell per square metre.
What instruments were used to collect this information?
5. How do humans impact on the atmosphere?
Human activities cause atmospheric pollution: the release of harmful substances called pollutants into the
atmosphere.
Most pollutants are gases: sulphur dioxide, carbon dioxide and nitrogen oxide. They are produced by
combustion from motor vehicles, aeroplanes, by burning fossil fuels, and from industrial activities.
Air pollutants can also be particles of liquid and solid molecules: ash from forest fires, black smoke, dust and
soot.
Pollutants in the air can cause: respiratory system irritation, eye irritation, increase in asthmatic processes,
headaches…
Global warming
In the last century, our atmosphere has warmed between 0,5 and 0,9 ºC on average. Some scientists think that
air pollution is causing the Earth’s surface to heat up.
Acid rain
Rain is naturally slightly acidic due to carbon dioxide dissolved in it. Pollutants such as sulphur dioxide and
nitrogen oxide, form acids when mixed with the rain.
The hole in the ozone layer
Ozone exists throughout the atmosphere, mainly concentrated in the stratosphere. Ozone is being destroyed
by air pollution. Chemicals called chlorofluorocarbons (CFCs) used in aerosols and refrigerators escape into
the atmosphere. They react with ozone and destroy it. Harmful solar radiation may enter through this hole.
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Human activities that pollute the atmosphere
Human activity
Pollutant
Consequences
Gases used in aerosols, air
conditioners
CFC gases
Reduces the amount of gas in the ozone layer so more
ultraviolet radiation reaches the Earth. Skin cancer results.
Particles released from
burning coal and other fuels
Soot
Cities are dirtier. Buildings are damaged. Can cause lung
diseases.
Burning fossil fuels: coal,
petrol
Carbon dioxide
(CO2)
Global warming: tropical cyclones, polar ice melts, sea
levels rise, severe droughts.
Burning gasoline
Sulphur and
nitrate dioxides
Acid rain: damages buildings, vegetation and harms
herbivorous animals.
The hole in the ozone layer allows in harmful UV
rays. These cause sunburn.
Air contamination from industry.
Acid rain damages this statue
6th.Talk about pollutants.
Where
does (carbon dioxide)
do (CFC gases)
What damage
does it
do they
come from?
cause?
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6. What is the greenhouse effect?
The greenhouse effect is a natural phenomenon. It is
essential for keeping he temperatures on Earth suitable
for life.
The atmosphere absorbs a great amount of solar
radiation. CO2 in the atmosphere acts like the glass
walls of a greenhouse. It traps the heat and prevents it
from returning into space. In this way the Earth does
not lose too much heat. If there were no atmosphere,
our planet would be much colder.
The increase of carbon dioxide
The amount of carbon dioxide in the atmosphere has
gradually increased over the last 200 years. Carbon
dioxide is produced when fossil fuels are burned; by
living things breathing; by fires, and by erupting
volcanoes.
Some CO2 is dissolved in the oceans and absorbed by
growing plants. Unfortunately, people are destroying
plants and burning more and more fossil fuels. This
means more carbon dioxide is produced. An increase
in carbon dioxide means more heat is trapped.
Therefore the average temperature of the Earth is
increasing.
Protecting the atmosphere
When pollution is reduced, global warming, the hole in
the ozone layer and acid rain are also reduced. By
saving energy, the atmosphere will improve and our
health will be much better. You are part of the solution:
- Use hot water carefully: do not waste it
- Turn off unnecessary heating and electrical devices
- Travel by public transport, by bike or on foot
- Avoid aerosols with CFCs
- Recycle paper, plastic and glass
- Plant trees
7th.Match the words with their definitions.
1.
2.
3.
4.
5.
6.
7.
8.
The symbol of this colourless and odourless gas is N2
This gas is necessary for photosynthesis
The first living beings produced this by photosynthesis
It is divided into four layers
This is the highest and the thickest layer of (4)
This layer of (4) contains clouds of dust
The ozone layer is found here
It contains 80 % of the total mass of the atmosphere
a)
b)
c)
d)
e)
f)
g)
h)
The mesosphere
The atmosphere
The troposphere
Nitrogen
Oxygen
The ionosphere
Carbon dioxide
The stratosphere
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8th.Find eight words connected to weather.
Q
P
A
D
S
G
S
G
Y
H
R
F
S
D
F
N
G
J
G
E
K
F
C
L
O
U
D
I
S
O
B
A
R
W
K
D
N
S
B
V
C
W
X
Z
H
H
U
M
I
D
I
T
Y
A
M
R
A
I
N
N
J
Y
I
F
E
F
S
D
D
G
T
L
9th.Complete each definition with a word from activity 8th. Use the plural where necessary.
1. _________________ are formed when rising air cools
2. _________________ is the concentration of water vapour in the atmosphere.
3. _________________ are the currents that move air masses around in the atmosphere.
4. _________________ can be low or high, moving towards a land mass or towards the sea.
5. _________________ is precipitation which falls to the ground in the form of water drops.
6. _________________ is precipitation which falls in the form of little balls of ice.
7. _________________ is precipitation made of soft white flakes.
8. _________________ connect points with the same atmospheric pressure on weather maps.
10th.
Complete the sentences:
1. Atmospheric pressure is measured with a _________________.
2. Some gases used in _________________ are pollutants.
3. _________________ is the height above sea level.
4. Temperature is measured with a _________________.
5. _________________ is the gas that combines with oxygen to produce water.
6. The _________________ measures the amount of rainfall per square metre.
7. The _________________ is located between the stratosphere and the ionosphere.
8. Atmospheric pressure, which is shown in _________________ , changes with the differences in
altitude.
11th.
True or false? Write T or F. The correct the false sentences.
1. Temperatures are higher at the Equator because solar energy is more spread out.
2. In summer, the sea releases heat, keeping coastal areas warmer.
3. Cold ocean currents can make areas cooler.
4. Snow occurs when water vapour in the air freezes.
5. Cumulus clouds form above 6000 m.
6. Cirrus clouds normally mean good weather.
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12th.
Complete the chart with information about atmospheric pollution.
HUMAN ACTIVITIES
POLLUTANT
CONSECUENCES
Burning fossil fuels
Burning gasoline
Acid rain
CFC gases
Soot
13th.
Cities are dirtier. Buildings are
damaged. Can cause lung
disease.
Write three reasons why the atmosphere is essential for life. Use these ideas:
a) Sun’s radiation
b) Gases and living things
c) Control of Earth’s temperature
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