Earth's Atmosphere Flashcards
What did the early atmosphere mainly consist of?
The early atmosphere contained mainly CO2 and water vapour. There was little or no oxygen present.
How did the oceans form in the early Earth?
Water vapour condensed and fell to the surface of the Earth, forming the oceans.
What happens to carbon dioxide when water vapour condenses?
Large amounts of CO2 dissolved in the oceans.
What were precipitated during the process of CO2 dissolving in the oceans?
Carbonate substances were precipitated, which later formed sediments.
How did carbon dioxide levels decrease in the atmosphere?
Photosynthesis by green plants and algae absorbed considerable amounts of carbon dioxide.
What happens to the remains of organisms that died after absorbing CO2?
Their remains locked the atmospheric carbon into the rocks.
What is the significance of marine algae in oxygen production?
Marine algae are thought to be responsible for about 90% of all the atmospheric oxygen produced.
How can the percentage of oxygen in the air be investigated?
By passing a known quantity of air over a metal, which reacts with oxygen to form a metal oxide.
What is the test for oxygen?
Placing a glowing splint inside a test tube of gas; if the gas is oxygen, the splint will relight.
What is the enhanced greenhouse effect?
It is caused by increasing levels of carbon dioxide and methane, trapping extra heat energy.
What are the sources of carbon dioxide?
Combustion of wood and fossil fuels, respiration of plants and animals, thermal decomposition of carbonate rocks.
What are the sources of methane?
Digestive processes of animals, decomposition of vegetation, bacterial action in swamps and rice paddies.
What methods are used to estimate past climate conditions?
Analysis of the fossil record and tree rings, and analysis of gas bubbles trapped in ice.
What is the expected impact of increased greenhouse gases?
The average temperature of the Earth is expected to increase, leading to global warming.
What are some effects of global warming?
Difficulties in obtaining fresh drinking water, melting of polar ice caps, flooding, and destruction of ecosystems.
How can CO2 emissions be reduced?
By using renewable energy supplies such as solar or wind energy instead of burning fossil fuels.
What are some ways to mitigate the effects of climate change?
Constructing good defence systems, developing new farming methods, and building effective irrigation systems.
