Earth + Atmosphere Flashcards
What was the earth’s surface like in the early atmosphere?
Originally molten for millions of years and almost no atmosphere
Eventually the Earth’s crust formed and cooled down causing water vapour in the atmosphere to condense liquid water to form oceans.
But volcanoes kept erupting, releasing gases from inside the earth.
The gases produced were mainly carbon dioxide but also steam, methane and ammonia.
What were the levels of carbon dioxide and oxygen like in the early atmosphere?
Very little oxygen and very high levels of Carbon dioxide and water vapour.
What did rocks containing ion oxide suggest?
Oxygen levels began to increase as microorganisms May have produce the oxygen.
What happened with Carbon dioxide later on?
A lot of the early carbon dioxide dissolved into the oceans so the levels of carbon dioxide dropped.
What happened when green plants evolved over earth?
Because many plants need to photosynthesis go make energy, they were producing oxygen which increased the levels of oxygen in the atmosphere.
Stromatolites are caused by oxygen-releasing micro-organisms so we’re proof that organisms were photosynthesising.
How was nitrogen put into the atmosphere?
It was formed by ammonia reacting with oxygen
Also released by denitrifying bacteria
Why did nitrogen levels in the atmosphere increase?
Nitrogen isn’t very reactive to it was being made but wasn’t being broken down.
What happens to the levels of oxygen and carbon dioxide now?
The amount of oxygen had gradually built up and most carbon dioxide eventually got locked up in fossil fuels and sedimentary rocks
What is the test for oxygen?
If you put a glowing splint into a test tube, it will relight if oxygen is present
What happened next in the atmosphere?
The build-up of oxygen in the atmosphere killed off early organisms who couldn’t tolerate it
But allowed the evolution of more complex organisms that use oxygen
The oxygen also created the ozone layer which blocked harmful rays from the sun
Barely any carbon dioxide
What is today’s atmosphere mainly consisted of?
Approx 78% nitrogen and 21% oxygen
Very small amounts of carbon dioxide, noble gases and water vapour
What is the greenhouse effect?
Energy from the sun is transferred to the Earth by waves I.e. light or infrared.
Some energy is absorbed by the Earth’s surface warming it up.
The warm earth emits infrared waves
Same gases in the air absorb energy transferred from these infrared waves
When the gases re-emit the energy, some of it goes back to the Earth surface and warms it.
How has the human population increasing rapidly caused?
A higher demand for energy - heating, lighting e.t.c
Where does this increased energy consumption come mainly from?
Burning fossil fuels which release more carbon dioxide
How else are carbon dioxide levels increasing?
To build houses and grow food, more trees are being cut down (deforestation).
Because plants are the main thing taking carbon dioxide out of the atmosphere (photosynthesis), the less plants, the increase in carbon dioxide.
