Structure of the Atmosphere
What is the atmosphere?
The layer of gases, vapour and dust particles surrounding the Earth.
What is the greenhouse effect?
A natural process where gases trap heat and keep Earth warm.
What is atmospheric pollution?
When harmful gases or substances are present in the air in damaging amounts.
What gas mainly causes acid rain?
Sulphur dioxide (SO₂)
What is a carbon footprint?
The total amount of greenhouse gases produced by human activities.
Which layer of the atmosphere is known as the “weather zone”?
Troposphere
What type of radiation does the Earth re-emit after being heated by the Sun?
Long-wave (infrared) radiation
What is the difference between a primary and a secondary pollutant?
Primary pollutants are released directly; secondary pollutants form after chemical reactions in the atmosphere.
What is acid rain?
Precipitation with a pH below 6 caused by sulphur dioxide and nitrogen oxides.
Name one way to reduce fossil fuel use.
Using renewable energy such as wind or solar power.
Name the four main layers of the atmosphere in order from the Earth’s surface.
Troposphere, Stratosphere, Mesosphere, Thermosphere
Name two greenhouse gases.
Carbon dioxide, methane, nitrous oxide
Name one source of particulate matter (PM).
Vehicle exhausts, fuel combustion, tyre wear, mining, dust
Where is “good ozone” found?
In the stratosphere
What does a catalytic converter do?
Converts harmful vehicle gases into less harmful substances.
Why does atmospheric pressure decrease with altitude?
Because there are fewer air molecules as gravity pulls most gases toward Earth’s surface.
Why is the natural greenhouse effect essential for life on Earth?
It keeps Earth about 33°C warmer, allowing liquid water and life to exist.
Explain how photochemical smog forms.
Sunlight reacts with pollutants such as VOCs and nitrogen oxides to form ground-level ozone.
Why is the ozone hole more severe over Antarctica?
The temperature is very low which leads to cold air being trapped and creating clouds filled with CFC's. The chlorine destroys the ozone.
Give one advantage and one disadvantage of carbon capture and storage (CCS).
Advantage: reduces CO₂ emissions. Disadvantage: expensive and long-term storage is uncertain.
Explain why temperature decreases with height in the troposphere but increases in the stratosphere.
In the troposphere, heat comes from Earth’s surface and decreases with height. In the stratosphere, ozone absorbs UV radiation, causing temperature to increase with altitude.
Explain how human activities enhance the greenhouse effect.
Burning fossil fuels, deforestation, agriculture and industry increase greenhouse gases, trapping more heat and causing global warming.
Explain why air pollution can become worse on calm, windless days.
On calm days there is little or no wind to spread polluted air away. This means pollutants build up near the ground instead of dispersing. As pollution becomes more concentrated, smog levels increase and air quality gets worse, especially in cities
Explain how human activities cause ozone depletion.
Human activities released CFCs from aerosols, refrigerators and air conditioners. These gases rise into the stratosphere where UV radiation breaks them down, releasing chlorine. The chlorine destroys ozone molecules, thinning the ozone layer.
Why are international agreements essential for managing atmospheric pollution?
Because air pollution crosses borders and requires global cooperation to reduce emissions effectively.