Flashcards · 5014 · Topic 4

The atmosphere and human activities flashcards

16 cards on Topic 4, subtopics 4.1 to 4.4. Pick a subtopic or study them all.

Study mode needs JavaScript. Every card is listed below, so you can still cover the answers and test yourself.

All 16 cards

For a quick read-through or printing. Cover the right-hand side to test yourself.

Give the approximate percentages of the main gases in dry air: Nitrogen about 78%, oxygen about 21%, argon just under 1%, carbon dioxide about 0.04%.
Which atmospheric layer contains the ozone layer, and which holds our weather?: The ozone layer is in the stratosphere. Weather happens in the troposphere, the lowest layer.
Why is the natural greenhouse effect necessary for life?: Greenhouse gases trap some of the heat radiated from the Earth’s surface, keeping it warm enough for liquid water.
Name four greenhouse gases: Carbon dioxide, methane, water vapour and nitrous oxide.

Natural vs enhanced greenhouse effect: Natural: keeps the Earth warm enough for life. Enhanced: extra warming caused by greenhouse gases added by human activities.
Name human activities that release methane: Rice paddies, cattle farming, landfill sites and leaks from gas extraction.
Why does global warming make sea level rise?: Seawater expands as it warms (thermal expansion), and melting land ice adds water to the oceans.
Is a sea wall mitigation or adaptation? Is tree planting?: A sea wall is adaptation: it copes with the effects. Tree planting is mitigation: it reduces the cause by absorbing carbon dioxide.

Which gases cause acid rain, and where do they come from?: Sulfur dioxide, from burning sulfur-containing fossil fuels and smelting ores, and nitrogen oxides, from vehicle engines and power stations.
What is the pH of normal rain, and why is it slightly acidic?: About 5.6, because carbon dioxide dissolves in it. Acid rain has a lower pH.
How does acid rain damage forests?: It washes nutrients out of the soil, releases aluminium that damages tree roots, and damages leaves directly.
Scrubbers vs catalytic converters: Scrubbers (flue-gas desulfurisation) remove sulfur dioxide from power station emissions. Catalytic converters reduce nitrogen oxides from vehicle exhausts.

Which chemicals destroy stratospheric ozone?: Chlorofluorocarbons (CFCs), formerly used in aerosols, refrigerators and foam. Ultraviolet light releases chlorine from them, which breaks down ozone.
Why does a thinner ozone layer harm health?: More ultraviolet radiation reaches the ground, increasing skin cancer and cataracts.
Why is the Montreal Protocol (1987) seen as a success?: Countries agreed to phase out CFCs and similar chemicals, replacements were introduced, and the ozone layer is slowly recovering.
How do ozone depletion and climate change differ?: Ozone depletion is caused mainly by CFCs and lets in more ultraviolet radiation. Climate change is caused mainly by extra greenhouse gases trapping heat.