KAJ Earth's Atmosphere Flashcards
(40 cards)
When was the Earth formed?
Earth was formed 4.6 billion years ago
How do scientists know what the early atmosphere was like?
scientists have reconstructed what the atmosphere was like based on gas bubbles trapped in ancient rocks/ice and planets and their moons in the solar system
How was the early atmosphere formed?
Through volcanic eruptions
- they believe volcanoes released CO2, N2 and H2O(g) (water vapour) forming the early atmosphere
How were oceans formed?
All this water vapour cooled and it fell as rain, forming the oceans
OR
Icy comets rain down on Earth, melting and adding to its water stores
What was the Earth’s atmosphere like as it began to stabilise?
As Earth began to stabilise it was mainly CO2 - there would have been N2, water vapour and traces CH4 and NH3, but very little O2
What did the Earth’s early atmosphere resemble?
Resembles the atmospheres of Mars and Venus - our closest planets
When did the first organisms form?
The first organisms formed 3.4 billion years ago
What formed after the first organisms and when?
Then, bacteria and other simple organisms like algae formed 2.7 billion years ago
- Algae photosynthesised to release O2
What happened in the atmosphere after algae formed?
Over the next billion years O2 steadily rose in the atmosphere and CO2 fell as plants photosynthesised and algae and bacteria thrived in seas
What happened to the earth as plants evolved?
As plants evolved, they colonised the Earth surface
As the atmosphere became richer in O2, it became possible for the first animal forms to evolve
Why are most early organisms no longer alive as a species?
Most early microorganisms couldn’t survive the increasing o2 concentration but some survived (algea)
How did the mixture of gases in the earth’s early atmosphere form?
Some scientists suggest that the mixture of gases would have been formed from solar debris –> similar to comets smashing into Earth and vaporising around 500 million years its formation
How are/were fossil fuels formed?
The remains of ancient living things were crushed by large scale movements of the earth and were heated within the crust and formed fossil fuels
What type of rock is coal?
coal is sedimentary rock
How were crude oil and natural gas formed?
crude oil and natural gas were formed from the remains of plankton deposited in muds on the seabed –> found deposited under layers of rock
Why has CO2 levels not changed that much during the last 200 millions years?
due to the carbon cycle
How were CO2 and N2 formed in the atmosphere, due to reactions with oxygen?
methane and ammonia found in the early atmosphere reacted with oxygen to make co2 and N2
What are the main greenhouse gases?
the main greenhouse gases are co2, ch4 and water vapour
What do greenhouse gases do?
greenhouse gases absorb energy radiated from the earth’s surface
- insulate the earth
- leads to global warming due to lots of CO2
How much energy reaching earth from the sun is reflected back into space?
30%
What wavelength do greenhouse gases let pass through the earth’s atmosphere?
greenhouse gases let short wavelength EM waves pass through
Why does global warming occur?
earth cools down by emitting infrared radiation but greenhouse gases absorb it
What happens if there is a high proportion of greenhouse gases in the atmosphere?
the higher the proportion of greenhouse gases in the atmosphere, the more energy that is absorbed
What has happened over the last century to increase levels of CO2 in the earth’s atmosphere?
over the last century burning fossil fuels to generate electricity has increased co2 levels greatly
