C11- Earth's Atmosphere Flashcards
Describe the earth’s early atmosphere
Earth is 4.6 billion years old and so we are not certain about what it was like but there are 2 main theories. One theory is that volcanoes released carbon dioxide, CO2, water vapour, H2O, and nitrogen, N2 and that these gases formed the early atmosphere. Water vapour in the atmosphere condensed as the earth gradually cooled down, and fell as rain. Water collected in hollows in the crust as the rock solidified and the first oceans were formed. Another theory is that comets could also have brough water to earth. As icy comets rained down on the surface of the earth, they melted, adding to its water supplies. The atmosphere remained quite stable until life first appeared on earth.
How was oxyegn formed in the early atmosphere?
Bacteria and other simple organisms such as algae evolved. Algae could use energy from the sun to make their own food by photosynthesis, which produced oxygen as a waste product. Over the next billion years rose steadily as algae and bacteria thrived in seas. More and more plants evolved all photosynthesising removing carbon dioxide and making oxygen.
What is the composition of earth’s early atmosphere?
Carbon dioxide + water — glucose + oxygen
6CO2 + 6H2O — C6H12O6 + 6O2
—= energy from sunlight
Have the levels of carbon dioxide decreased or increased in the atmosphere?
Decreased
List the names and symbols of the gases in dry air
Nitrogen (N) Oxygen (O) Argon (Ar) Neon (Ne) Krypton (Kr) Xenon (Xe)
Where did ammonia and methane in the atmosphere come from?
Small proportions could have come from volcanoes.
How was the proportion of carbon dioxide from the early atmosphere removed?
It has gone mostly into living organisms and into materials formed from living organisms. Algae and plants decreased the percentage of carbon dioxide in the early atmosphere by photosynthesis.
What is the composition of dry air?
Nitrogen (78%) Oxygen (21%) Argon (0.9%) Carbon dioxide (0.04%) Neon, Krypton and xenon (less than (0.1%)
How can carbon dioxide form sedimentary rocks?
The layers of sediment are are pressured and deposited to form sedimentary carbonate rocks, such as limestone, containing mainly calcium carbonate, CaCO3.
Describe the greenhouse effect
The ground warms up and heat is emitted from the Earth’s surface. Some heat escapes into space but some is absorbed by greenhouse gases. It is re-emitted and does not escape.
Name 3 greenhouse gases
Carbon dioxide
Methane
Water vapour
State some human activities that will effect the proportion of greenhouse gases
Owning an increasing amount of grazing cattle
Increase in human population produces more waste to dispose of in landfill sites.
How do greenhouse gases increase the temperature of the earth?
The greenhouse gases let short-wavelength electromagnetic radiation ,e.g. ultraviolet light, pass through. The surface of the earth cools down by emitting longer wavelength infrared (thermal) radiation. However, greenhouse gases absorb infrared radiation. The radiation stimulates the bonds in these molecules to vibrate, bend, and stretch more vigorously, raising their temperature. So some of the energy radiated from the surface of the earth gets trapped in the atmosphere and the temperature rises. The higher the proportion of greenhouse gases in the air, the more energy is absorbed.
Why do scientists and the public disagree about the cause of climate change?
Because there is no ‘hard evidence’ of any theory or reason being correct. There are multiple different sources and reasons that could be but none of them are proven.
What is the difference between greenhouse effect and global warming?
Global warming is the long term change in climate that has happened cyclically throughout earth’s history, but is currently happening at a much faster rate than normal. This is usually associated with the greenhouse effect, which is a natural phenomenon that allows the Earth to trap heat.
