Chemistry of the atmosphere Flashcards
The relative amounts of different gases in the Earth’s atmosphere has ——————- for the past couple of hundred million years.
stayed quite consistent
The relative amounts of different gases in the Earth’s atmosphere has stayed quite consistent for the past couple of hundred million years:
- 78% nitrogen
- 21% oxygen
- Small amounts of other gases (e.g. noble gases, carbon dioxide and water vapour)
Main gases in the Earth’s atmosphere :
- water vapour
- carbon dioxide
- noble gases
- oxygen
- nitrogen
The Earth was formed roughly ————- years ago.
4.6 billion
The Earth was formed roughly 4.6 billion years ago. We don’t have much evidence from that long ago, but the common view (consensus view) among scientists is:
- Age of the volcanoes
- Reduction of carbon dioxide levels
Highly active volcanoes were littered across the Earth’s surface for the ———— of its existence.
first billion years
The frequent eruptions of these volcanoes resulted in the …
release of lots of carbon dioxide (as well as smaller amounts of gases such as water vapour, methane, ammonia and nitrogen).
Scientists think carbon dioxide dominated the early atmosphere in a similar way to …
modern-day Mars.
Scientists think —————— dominated the early atmosphere in a similar way to modern-day Mars.
carbon dioxide
Levels of atmospheric nitrogen have …
accumulated steadily.
The oceans were formed as a result of the …
water vapour condensing.
The formation of the oceans caused a …
significant reduction in carbon dioxide levels in the atmosphere.
Carbonate precipitates were produced by ——————. These precipitates were deposited as sediment.
reactions between the dissolved carbon dioxide and seawater.
Carbonate precipitates were produced by reactions between the dissolved carbon dioxide and seawater. These precipitates were deposited as …
sediment.
Name the 2 gases with the largest proportions in the modern atmosphere.
- oxygen
- nitrogen
——————————- were produced by reactions between the dissolved carbon dioxide and seawater. These were deposited as sediment.
Carbonate precipitates
Photosynthesis is the process in which …
light energy is used to produce glucose and oxygen from carbon dioxide and water.
Photosynthesis increased the atmospheric concentration of …
oxygen
Algae were the first photosynthetic organisms to evolve. This happened about ———- years ago.
2.5-2.7 billion
Photosynthesising plants then began to evolve over the next billion years. This led to an ever-increasing rate of …
oxygen accumulating in the atmosphere
More complex life forms, such as animals, began to evolve once …
a threshold concentration of oxygen was reached.
What caused the oxygen levels in the atmosphere to increase?
Photosynthesis
What is needed for photosynthesis to take place?
- Carbon dioxide
- light energy
- water
So, the photosynthetic action of algae and plants removed ————— from the atmosphere.
carbon dioxide
The formation of oceans removed large amounts of —————- from the atmosphere.
carbon dioxide
The evolution of marine animals removed ———- from the oceans as the animals used these to build their shells and skeletons.
carbonates
At least 3 factors caused atmospheric carbon dioxide to decrease:
- Photosynthesis
- Oceans
- Marine animals
Greenhouse gases cause the greenhouse effect. This helps …
keep the Earth warm enough for life.
But, the greenhouse effect can cause …
global warming if it’s too strong.
The process of the greenhouse effect is:
- The Sun emits short-wavelength radiation that enters the atmosphere and travels towards the Earth.
2 .The Earth absorbs a portion of this radiation, but longer wavelength radiation is reflected back into the atmosphere. - Greenhouse gases can’t absorb the short wavelength radiation emitted by the Sun, but they can absorb the reflected radiation.
- The gases re-radiate this as heat energy, some of which heads back to Earth.
- This increases the temperature at the Earth’s surface.
Which region on Earth do you think reflects the greatest proportion of radiation arriving from the Sun?
The white surface of Antarctica makes it the most reflective region in the world.
This is one of the reasons why it’s so ridiculously cold!
Certain human activities cause the atmospheric concentrations of greenhouse gases to increase:
- Burning fossil fuels
- Agriculture
- Deforestation
- Landfill sites
Burning fossil fuels releases carbon, in the form of carbon dioxide. This carbon dioxide had been stored away for …
millions of years previously.
Farm animals release ——— during digestion.
methane
As the global population continues to rise, the scale of agriculture is ————. This means that more methane is being released into the atmosphere by livestock.
increasing
As the global population continues to rise, the scale of agriculture is increasing. This means that …
more methane is being released into the atmosphere by livestock.
As we cut down more and more trees, the global rate of photosynthesis will …
decrease
Given that carbon dioxide is a reactant in the equation for photosynthesis, this means that less carbon dioxide will be …
removed from the atmosphere by this process.
The number and size of landfill sites is …
increasing
Landfill sites release ———— , which is a greenhouse gas.
methane
Why is it important to maintain satisfactory levels of greenhouse gases on earth?
- Without greenhouse gases, temperatures would be too low to support life.
- However, high concentrations of greenhouse gases cause temperatures to rise too high, which also threatens life on Earth.
Although the temperature at the Earth’s surface naturally ———- , the recent increase in temperature is connected to increasing atmospheric greenhouse gas concentrations.
changes