Atmosphere Flashcards
What are the proportions of gases in today’s atmosphere?
~80% nitrogen (N₂), ~20% oxygen (O₂), small amounts of carbon dioxide (CO₂), water vapour (H₂O), and noble gases.
How long have atmospheric gas proportions remained stable?
About 200 million years.
What was the Earth’s early atmosphere like?
Mostly carbon dioxide (CO₂) with little to no oxygen (O₂), similar to Mars & Venus today.
What process led to the formation of oceans?
Water vapour from volcanic eruptions condensed as the Earth cooled.
How did carbon dioxide levels decrease?
Dissolved in oceans → formed sediments; taken in by plants & algae during photosynthesis; trapped in fossil fuels & sedimentary rocks (e.g., limestone, coal).
How did oxygen levels increase?
Photosynthesis by algae and plants produced oxygen, allowing animals to evolve.
What are the main pollutants produced by burning fuels?
Carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen oxides, particulates (soot & unburnt hydrocarbons).
What is incomplete combustion?
When there is not enough oxygen, carbon monoxide and soot (carbon particulates) are produced instead of carbon dioxide.
What is carbon monoxide and why is it dangerous?
A toxic, colourless, odourless gas that prevents red blood cells from carrying oxygen.
What are the effects of sulfur dioxide and nitrogen oxides?
Cause acid rain and respiratory problems in humans.
What is global dimming and what causes it?
Tiny particulates (soot) block sunlight, reducing temperatures and affecting rainfall patterns.
What are greenhouse gases?
Gases that trap heat in the Earth’s atmosphere, maintaining temperatures high enough to support life.
What are the main greenhouse gases?
Carbon dioxide (CO₂), methane (CH₄), and water vapour (H₂O).
What is the greenhouse effect?
The Sun emits electromagnetic radiation, most of which passes through the atmosphere. The Earth absorbs radiation, warming the surface. Some infrared radiation is emitted back into space. Greenhouse gases absorb some infrared radiation, preventing heat from escaping. The atmosphere warms up, causing the greenhouse effect and global warming.
How do human activities increase CO₂ levels?
Burning fossil fuels (driving, generating electricity). Deforestation (fewer trees absorbing CO₂).
How do human activities increase CH₄ levels?
Raising livestock (cows produce methane). Decomposing waste in landfills (releases methane).
Why is climate change difficult to model accurately?
The climate is a complex system, making predictions difficult. Media reports may be biased or oversimplified.
What is a major cause of climate change?
An increase in global average temperature due to greenhouse gases.
What are four potential effects of climate change?
Species extinction due to habitat loss. Rising sea levels from melting ice caps. Mass migration due to droughts and flooding. Lower crop yields, affecting food production.
What is a carbon footprint?
The total amount of CO₂ and other greenhouse gases emitted over the full life cycle of a product, service, or event.
How can we reduce our carbon footprint?
Using renewable energy instead of fossil fuels. Reducing travel & transportation emissions. Planting more trees to absorb CO₂.
What are the challenges in reducing carbon footprints?
Costs may be high. Planting trees takes up land needed for farming. Changing habits (reducing energy use) can be difficult.
