Download UNIT 5_THE ATMOSPHERE

UNIT 5. THE ATMOSPHERE
Designed by Conchi 1B1
1. THE ATMOSPHERE
The atmosphere is a thin layer of gases that
surrounds the Earth.
The atmosphere is made up of air.
Air: It is a mixture of gases that forms the atmosphere. It
is composed of nitrogen (78%), oxygen (21%), carbon
dioxide (0.03%) and very small amounts of other gases
(helium, argon, neon, ozone, water vapor, etc.).
In the atmosphere there is also: powder, bacteria, pollen,
etc.
1. THE ATMOSPHERE
The primitive atmosphere: the atmosphere was
very difference 4600 millon years ago.
• Was made up of:
-
Water vapour
Carbon dioxide
Hydrogen
Ammonia
Methane
Other oxides
• The first living beings (bacteria),
produced oxygen by photosynthesis.
• Molecules formed when chemical
reactions took place between gases.
These molecules fell to Earth with rain.
1. THE ATMOSPHERE
Importance of the atmosphere:
In the first place, the atmosphere contains oxygen which is
necessary for living beings. We all need air to breathe.
Secondly, the temperature of the Earth depends on the
atmosphere. The atmosphere favours the warming of the
Earth. It absorbs a great part of solar radiation and prevents
this from escaping back up into space. This is called the
greenhouse effect. Without the atmosphere our planet
would be much colder.
Finally, the atmosphere is a very important filter. There is a
layer of a gas called ozone which protects us from some
dangerous radiation.
2. THE LAYERS OF THE ATMOSPHERE
The layers of the atmosphere are:
Troposphere: It is the lowest layer of the Earth's atmosphere. It extends from
0 to 12 km of altitude (very thin), but contains 80% of the total mass of the
atmosphere. The temperature decrease with the altitude. The weather,
clouds, wind, rain, etc. occur in the troposphere.
Stratosphere: extends from 12 km to 50 km. There is an increase of
temperature with the altitude. The ozone layer is in the middle.
Mesosphere: extends from 50 km to 80 km. Here the temperature is very
low. It contains clouds of ice and dust. The meteorites that fall to the Earth
become incandescent in this layer (shooting stars)
Thermosphere or ionosphere: extends from 80 km to 500 km. In this layer
there are very few gases. The temperature increase a lot due to X-rays and
gamma rays from Sun. Auroras occur in the ionosphere. Comets appear here.
Exosphere: begins at 500 km of altitude and it isn’t really clear where it ends.
It is the outermost layer of the Earth's atmosphere. The atmospheric
pressure and temperature are low.
2. THE LAYERS OF THE ATMOSPHERE
The layers of the atmosphere are:
500 km
80 km
50 km
12 km
3. THE WEATHER
The 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.
How are the clouds formed?: In the areas heated by the Sun, the water evaporates and goes up to the
troposphere. In the high part of the troposphere, the water vapour cools down. The cold vapor is
condensed in small drops. Those drops form the clouds. There are three basic types of clouds: cirrus,
cumulus and stratrus.
Precipitation: Water that falls to the ground. They can be of several types.
Rain: The small drops join in the cloud, they weigh too much and they fall in the form of rain.
Snow: Snowflakes form in clouds where the temperature is freezing (0ºC). The ice crystals (flake) form
around tiny bits of powder that have been carried up into the atmosphere by the wind. As the snow
crystals grow, they become heavier and fall toward Earth.
Hail: The drops join, but instead of falling in the form of rain, the wind blows them up to high and cold
areas, they freeze and they form balls of ice that fall on the Earth.
Temperature: How hot or cold the air is.
Wind: Is the air moving.
How is the wind formed?: Hot air weighs less and goes up, the cold air of the high layers, comes and
occupies the place that the hot air left free. The wind is that current of air.
3. THE WEATHER
3. THE WEATHER
ATMOSPHERIC PRESSURE:
Air has weight.
The pressure it exerts on the
surface is called atmospheric
pressure.
It is caused by gravity
It is measured in millibars (mb)
PREDICTING THE WEATHER:
o Low pressure area or cyclones (L or B):
are unstable atmospheric situation.
When there is a cyclone over a particular
place the weather is usually very bad, it’s
windy and it rains or snows.
o High pressure area or anticyclones (H or A):
are stable situations and the weather is good.
When there is an anticyclone the weather is
sunny
4. THE METEOROLOGY
The 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.
Meteorological instruments:
A thermometer: is a device that measures the temperature. Temperatures are expressed in
centigrade grades (ºC) and in some countries in Fahrenheit grades (ºF).
A pluviometer (rain gauge): is a type of instrument that picks up and measures the quantity of
fallen rain. Unit: litre per square metre.
A barometer: is an instrument used to measure atmospheric pressure. Unit: mb
An anemometer: is a device to measure wind speed. Unit: m/s or Km/h
A hygrometer: is an instrument used for measuring humidity. Atmospheric humidity is
expressed as a percentage
A vane: is a movable device attached to an elevated object such as a roof for showing the
direction of the wind.
4. THE METEOROLOGY
5. ATMOSPHERIC POLLUTION
What is the atmospheric contamination?: It is the presence of a certain amount of
substances in the atmosphere that can damage or endanger the health of people and
of living creatures.
What contaminates the atmosphere?: The atmosphere can be contaminated in several
ways:
By polluting substances as noxious gases or particles of smoke and ashes.
By noises and light.
Effects of contamination:
The climate suffers from changes.
The biosphere is seriously harmed.
The health of people worsens.
Constructions and materials deteriorate more quickly.
5.1 POLLUTION IN CITIES
All cities are a source of pollution for the atmosphere.
Common air pollutants are carbon monoxide, carbon dioxide, sulfur dioxide
and nitrogen oxides.
They come from industries, homes and motor vehicles.
The contaminating substances can cause respiratory diseases and lack of
visibility. This problem is called smog (smoke + fog = smog).
5.2 GLOBAL WARMING
The average temperature of the planet is increasing since the mid-twentieth
century. This phenomenon is called global warming and it’s a result of the
increase in the greenhouse effect.
The greenhouse effect is a natural phenomenon and it is essential for keeping
the Earth warm enough for living beings. But, some polluting gases, as carbon
dioxide (CO2), increase this effect too much.
Carbon dioxide is released by the burning of coal and oil in our cars and power
stations. Besides, the deforestation also increases the CO2 levels.
Global warming has many harmful consequences: temperatures rise, ice at the
North and South Poles melts, sea level rises and many coastal cities may be
flooded.
We should save energy, stop using oil, gas and petrol and we should change to
green energy (wind power, solar power, hydroelectricity...) and, of course,
stop cutting down trees
https://www.youtube.com/watch?v=aFsC4sGzMJ8
5.3 THE HOLE IN THE OZONE LAYER
Ozone (O3) is a triatomic molecule, consisting of three oxygen atoms. Ozone in
the stratosphere filters ultraviolet light from reaching the Earth's surface.
There is an area where the ozone layer is disappearing. This area is called the
hole in the ozone layer.
Due to the hole in the ozone layer, harmful radiation affects our health causing
skin diseases.
The disappearance of ozone is caused by some gases called CFC. These gases
were in refrigerators and aerosols but today they are substituted by other
gases which do not damage the ozone layer.
https://www.youtube.com/watch?v=
u9ztDSbSrFI
5.4 ACID RAIN
Acid rain is a rain or any other form of precipitation that is unusually acidic.
Acid rain is caused by emissions of sulfur dioxide and nitrogen oxide, which
react with the water molecules in the atmosphere to produce acids.
Acid rain produces adverse impacts on forests, freshwaters and soils. Besides
it is harmful to insect and aquatic life-forms, as well as causing damage to
buildings and having impacts on human health.
6. 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 wate it
Turn off unneccessary heating and electrical devices
Travel by public transport, by bike or on foot
Avoit aerosols with CFCs
Recycle paper, plastic and glass
Plant trees.