ESS – November Exam Notes
6.1 – Introduction to the Atmosphere
Significant Ideas:
o the atmosphere is a dynamic system which is essential to life on Earth.
o the behaviour, structure and composition of the atmosphere influences variations in all
ecosystems.
Knowledge and Understanding:
o the atmosphere is a dynamic system (with inputs and outputs), which has undergone
changes through geological time.
o the atmosphere is predominantly a mixture of nitrogen and oxygen, with smaller amounts
of carbon dioxide, argon, water vapour and other trace gases.
o human activities impact the atmospheric composition through altering inputs and outputs
of the system – changes in the concentrations of atmospheric gases such as ozone, carbon
dioxide, and water vapour have significant effects on ecosystems.
o most clouds form in the troposphere and play an important role in the albedo effect for the
planet.
o the greenhouse effect of the atmosphere is a natural and necessary phenomenon
maintaining suitable temperatures for living systems.
The Composition of the Atmosphere
The structure and composition of the atmosphere varies with height. The atmosphere is a mixture of
solids, liquids, and gases that are held to the Earth by its gravitational force. The atmosphere is quite
similar in composition up to a height of about 80 km. It consists mainly of nitrogen (78%), oxygen (21
%), and argon (0.9%). There are also a variety of other trace gases, such as carbon dioxide and
ozone. There is also water vapour and solids (aerosols), such as dust and soot.
There is no outer limit for the atmosphere, but most weather occurs in the lowest 16–17 km. This
part of the atmosphere is known as the troposphere. Temperatures decrease with height in the
troposphere.
trace gases – gases that are found in small quantities but are very important (e.g. CO2)
aerosols – tiny solid materials held up in the atmosphere
weather – the state of the atmosphere over a short-time scale such as a few days; it includes
temperature, rainfall, cloud cover, wind speed and direction
Layers of the Atmosphere
The troposphere is the lowest part of the atmosphere. The next upper part of the atmosphere is the
stratosphere. It is separated from the troposphere by the tropopause. Above the stratosphere is the
mesosphere. The mesosphere is separated from the stratosphere by the stratopause. The highest
layer of the atmosphere is the thermosphere. It is separated from the mesosphere by the
mesopause.
Certain gases are concentrated at height. Ozone occurs in the stratosphere. It is mostly found at
around 10–50 km above the Earth. It is important for the filtering of harmful ultraviolet radiation.
ozone – a molecule made up of 3 atoms of oxygen
, 6.2 – Stratospheric Ozone
Significant Ideas:
o stratospheric ozone is a key component of the atmospheric system because it protects living
systems from the negative effects of ultraviolet radiation from the Sun.
o human activities have disturbed the dynamic equilibrium of stratospheric ozone formation.
o pollution management strategies are being employed to conserve stratospheric ozone.
Knowledge and Understanding:
o some ultraviolet radiation from the Sun is absorbed by stratospheric ozone causing the
ozone molecule to break apart – under normal conditions, the ozone molecule will reform;
this ozone destruction and reformation is an example of a dynamic equilibrium.
o ozone-depleting substances (CFCs) are used in aerosols, gas-blown plastics, pesticides and
refrigerants – halogen atoms (chlorine) from these pollutants increase destruction of ozone
in a repetitive cycle allowing more ultraviolet to reach the Earth.
o ultraviolet radiation reaching the surface of the Earth damages human living tissues,
increases the incidence of cataracts, mutation during cell division, skin cancer and other
subsequent effects on health.
o the effects of increased UV radiation on productivity include damage to photosynthetic
organisms, especially phytoplankton which form the basis of aquatic food webs.
o the United Nations Environment Programme (UNEP) has had a key role in providing
information and creating and evaluating international agreements for the protection of
stratospheric ozone.
o an illegal market for ozone-depleting substances continued and requires monitoring.
o the Montreal Protocol (1987) is an international agreement on the reduction of use of
ozone-depleting substances signed under the direction of UNEP – national governments
complying with the agreement have made national laws and regulations to decrease
consumption and production of halogenated organic gases such as CFCs.
Pollution management may be achieved by reducing the manufacture and release of ozone-
depleting substances. Methods for this reduction include:
1. recycling refrigerants
2. developing alternatives to halogenated pesticides
3. developing non-propellant alternatives
The Importance of Ozone
The ozone layer shields the Earth from harmful radiation that would otherwise destroy most life on
the planet. Ultraviolet radiation is absorbed by ozone. Ozone also absorbs some out-going, long-
wave radiation, so it is a greenhouse gas too.
The Formation and Destruction of Ozone
Ozone is created by oxygen rising up from the top of the troposphere and reacting with sunlight.
Ultraviolet radiation (short-wave radiation) breaks down oxygen molecules (O2) into two separate
oxygen atoms. The oxygen atoms (O) combine to form ozone (O3). Thus, natural processes create
ozone. Human activities can destroy ozone. Human production of chlorofluorocarbons (CFCs) is
linked to a decrease in ozone.
6.1 – Introduction to the Atmosphere
Significant Ideas:
o the atmosphere is a dynamic system which is essential to life on Earth.
o the behaviour, structure and composition of the atmosphere influences variations in all
ecosystems.
Knowledge and Understanding:
o the atmosphere is a dynamic system (with inputs and outputs), which has undergone
changes through geological time.
o the atmosphere is predominantly a mixture of nitrogen and oxygen, with smaller amounts
of carbon dioxide, argon, water vapour and other trace gases.
o human activities impact the atmospheric composition through altering inputs and outputs
of the system – changes in the concentrations of atmospheric gases such as ozone, carbon
dioxide, and water vapour have significant effects on ecosystems.
o most clouds form in the troposphere and play an important role in the albedo effect for the
planet.
o the greenhouse effect of the atmosphere is a natural and necessary phenomenon
maintaining suitable temperatures for living systems.
The Composition of the Atmosphere
The structure and composition of the atmosphere varies with height. The atmosphere is a mixture of
solids, liquids, and gases that are held to the Earth by its gravitational force. The atmosphere is quite
similar in composition up to a height of about 80 km. It consists mainly of nitrogen (78%), oxygen (21
%), and argon (0.9%). There are also a variety of other trace gases, such as carbon dioxide and
ozone. There is also water vapour and solids (aerosols), such as dust and soot.
There is no outer limit for the atmosphere, but most weather occurs in the lowest 16–17 km. This
part of the atmosphere is known as the troposphere. Temperatures decrease with height in the
troposphere.
trace gases – gases that are found in small quantities but are very important (e.g. CO2)
aerosols – tiny solid materials held up in the atmosphere
weather – the state of the atmosphere over a short-time scale such as a few days; it includes
temperature, rainfall, cloud cover, wind speed and direction
Layers of the Atmosphere
The troposphere is the lowest part of the atmosphere. The next upper part of the atmosphere is the
stratosphere. It is separated from the troposphere by the tropopause. Above the stratosphere is the
mesosphere. The mesosphere is separated from the stratosphere by the stratopause. The highest
layer of the atmosphere is the thermosphere. It is separated from the mesosphere by the
mesopause.
Certain gases are concentrated at height. Ozone occurs in the stratosphere. It is mostly found at
around 10–50 km above the Earth. It is important for the filtering of harmful ultraviolet radiation.
ozone – a molecule made up of 3 atoms of oxygen
, 6.2 – Stratospheric Ozone
Significant Ideas:
o stratospheric ozone is a key component of the atmospheric system because it protects living
systems from the negative effects of ultraviolet radiation from the Sun.
o human activities have disturbed the dynamic equilibrium of stratospheric ozone formation.
o pollution management strategies are being employed to conserve stratospheric ozone.
Knowledge and Understanding:
o some ultraviolet radiation from the Sun is absorbed by stratospheric ozone causing the
ozone molecule to break apart – under normal conditions, the ozone molecule will reform;
this ozone destruction and reformation is an example of a dynamic equilibrium.
o ozone-depleting substances (CFCs) are used in aerosols, gas-blown plastics, pesticides and
refrigerants – halogen atoms (chlorine) from these pollutants increase destruction of ozone
in a repetitive cycle allowing more ultraviolet to reach the Earth.
o ultraviolet radiation reaching the surface of the Earth damages human living tissues,
increases the incidence of cataracts, mutation during cell division, skin cancer and other
subsequent effects on health.
o the effects of increased UV radiation on productivity include damage to photosynthetic
organisms, especially phytoplankton which form the basis of aquatic food webs.
o the United Nations Environment Programme (UNEP) has had a key role in providing
information and creating and evaluating international agreements for the protection of
stratospheric ozone.
o an illegal market for ozone-depleting substances continued and requires monitoring.
o the Montreal Protocol (1987) is an international agreement on the reduction of use of
ozone-depleting substances signed under the direction of UNEP – national governments
complying with the agreement have made national laws and regulations to decrease
consumption and production of halogenated organic gases such as CFCs.
Pollution management may be achieved by reducing the manufacture and release of ozone-
depleting substances. Methods for this reduction include:
1. recycling refrigerants
2. developing alternatives to halogenated pesticides
3. developing non-propellant alternatives
The Importance of Ozone
The ozone layer shields the Earth from harmful radiation that would otherwise destroy most life on
the planet. Ultraviolet radiation is absorbed by ozone. Ozone also absorbs some out-going, long-
wave radiation, so it is a greenhouse gas too.
The Formation and Destruction of Ozone
Ozone is created by oxygen rising up from the top of the troposphere and reacting with sunlight.
Ultraviolet radiation (short-wave radiation) breaks down oxygen molecules (O2) into two separate
oxygen atoms. The oxygen atoms (O) combine to form ozone (O3). Thus, natural processes create
ozone. Human activities can destroy ozone. Human production of chlorofluorocarbons (CFCs) is
linked to a decrease in ozone.
