Atmosphere Flashcards
describe the composition of gases in the earth’s atmosphere using percentages
- ~80% nitrogen
- ~20% oxygen
- <1% other gases such as carbon dioxide, water vapour and noble gases
how did early intense volcanic activity helpform the early atmosphere and oceans?
- They released gases that made the early atmosphere very similar to the atmospheres of Mars and Venus today.
- These atmospheres have: a large amount of carbon dioxide,
little or no oxygen and small amounts of other gases, such as ammonia and methane - Volcanic activity also released water
vapour, which condensed as the Earth cooled to form the oceans. - Nitrogen was probably also released by volcanoes which gradually built up in the atmosphere because it is unreactive.
why did carbon dioxide in the atmosphere change (decrease) as the oceans were formed?
- The formation of sedimentary rocks- as the oceans formed, carbon dioxide dissolved to form soluble carbonate compounds so its amount in the atmosphere decreased. Carbonate compounds were then precipitated as
sedimentary rocks, eg limestone. - Uptake by living organisms- Carbon dioxide was also absorbed from the oceans into photosynthetic algae and plants. Many of these organisms, and the simple organisms in the food chains that they supported were turned into fossil fuels, eg crude oil, coal and natural gas, which all contain carbon.
1. Coal is a fossil fuel which was formed from trees which were in dense forests in low-lying wetland areas. Flooding caused the wood from these forests to be buried in a way that prevented oxidation taking place. Compression and heating over millions of years turned the wood into coal.
2. Crude oil and natural gas were formed from simple plants and tiny animals which were living in oceans and lakes. These small organisms died and their remains sank to the bottom where they were buried under sediments. The lack of oxygen prevented oxidation from occurring. Over millions of years, heat and pressure turned the remains of the organisms into crude oil and natural gas. Natural gas contains the smallest molecules and is often found on top of crude oil, trapped under sedimentary rock.
state the approximate time in earth’s history when algae evolved to start producing oxygen
approximately 2.7 billion years ago
how did oxygen in the earth’s atmosphere increase and what were the effects of a gradually increasing oxygen level?
- Algae evolved to make their own food by photosynthesis
- Photosynthesis by primitive plants and algae released oxygen, which gradually built up in the atmosphere.
- Eventually, the amount of oxygen present in the atmosphere enabled animals to evolve.
name 3 greenhouse gases
- water vapour
- carbon dioxide
- methane
how do greenhouse gases causem an increase in earth’s temperature?
- Electromagnetic radiation at most wavelengths passes through the Earth’s atmosphere.
- The Earth absorbs most of the radiation and warms up.
- The Earth radiates energy as infrared radiation.
- Some of the infrared radiation goes into space.
- Some of the infrared radiation is absorbed by greenhouse gases in the atmosphere.
- The lower atmosphere warms up.
what is the greenhouse effect and explain briefly how it works
- The retention of heat in the atmosphere caused by the build-up of greenhouse gases.
- greenhouse gases absorb heat radiated from the Earth then release energy in all directions, which keeps the Earth warm
list 4 human activities that produce greenhouse gases
- farming cattle releases methane
- farming rice in paddy fields releases methane
- burning fossil fuels in vehicles and
power stations releases carbon dioxide - deforestation releases carbon dioxide and reduces the absorption of carbon dioxide through photosynthesis
what 4 things should you consider when evaluating the quality of evidence on things like global warming?
- who did the research and whether they are trustworthy, skilled and experienced
- who funded the research, because that might cause some bias
- what methods were used to collect and analyse the data, because that might cause uncertainties in the evidence base
- which organisation is reporting or publishing the evidence
3 arguments against the idea that human activity caused a rise in global warming
- caused by natural factors and cycles of climate change
- climate science is complicated and it is difficult to predict and explain what will happen to global temperatures in the future, so scientists cannot be certain about global warming
- media may sometimes present opinions and articles which are simplified, inaccurate, based on only some of the evidence or biased
2 arguments for the idea that human activity caused a rise in global warming
- vast majority of scientists do believe that humans are responsible
- the majority of evidence in
peer-reviewed journals supports the theory
4 effects of global warming
- glaciers and polar ice melting
- sea levels rising
- patterns of rainfall changing, producing floods or droughts
- habitats changing
define carbon footprint
the total amount of carbon dioxide (and other greenhouse gases) which are emitted over the full life cycle of a product, service or event.
3 ways to reduce carbon footprint
- Maximise the efficiency of your energy use.
- Minimise your waste.
- Using renewable energy sources as an alternative to burning fossil fuels.
