The Earths Atmosphere Flashcards
What is the composition of gases in the atmosphere today
- The atmosphere today is 78% nitrogen
- The atmosphere today is also 21% oxygen
- There are also small amounts of other gases e.g carbon dioxide , water vapour and argon
What happened in the first billion years of the earth
In the first billion years of the earth scientists believe there was intense volcanic activity
-This volcanic activity released the gases that make up the atmosphere today
How did oceans from
Oceans formed when water vapour from the early atmosphere condensed as the earth cooled
What other gases did the volcanoes release
- Volcanoes released large amounts of carbon dioxide
- They also released nitrogen which gradually built up in the atmosphere due to its unreactive nature
- They also released small amounts of methane and ammonia
What are the differences between the composition of gases in the atmosphere today and the composition in the early atmosphere
- In the early atmosphere there was huge amounts of carbon dioxide but now there is only small amounts
- In the early atmosphere there was little/no oxygen but now oxygen makes up 21% of the atmosphere
Why did carbon dioxide levels fall
- Carbon dioxide levels fell because when oceans formed carbon dioxide dissolved into the oceans to form weak acids .These weak acids reacted with minerals in the sea to form particulates which formed sediments of carbonate rock on the seabed
- Some of the carbon dioxide was also used to make coral and used to make shells of organsims such as mussels
- Carbon dioxide was also taken in during photosynthesis
Why did oxygen levels rise in the atmosphere
- Oxygen levels rose in the atmosphere because around 2.7 billion years ago photosynthetic algae evolved in the oceans
- Photosynthesis produced oxygen which entered the atmosphere
- Over the following billion years plants evovled , this increased the amounts of oxygen in the atmosphere
How is coal formed
Coal is formed from the remains of ferns and trees that do not decompose. Over time these plant remains are covered with sediment and compressed at high temperatures to form coal
How is crude oil formed
Crude oil is formed from plankton. When they die they settle in mud in the seabed , if no oxygen in present they do not decompose.
-Over time the plankton is compressed by sediment and the heat and pressure converts it to crude oil
What do all fossil fuels contain
All fossil fuels contain trapped carbon. The carbon was part of the carbon taken in by photosynthsis.
What are three examples of greenhouse gases
Water vapour,methane and carbon dioxide are all greenhouse gases
What is the greenhouse effect ? What are the stages in how it happens ? ( long answer)
- Energy from the sun travels to the earth as short wavelength radiation
- Some of the short wavelength radiation reflects back to space but most of it passes through the atmosphere easily (This is because showt wavelength radiation does not interact strongly with gas molecules in the atmosphere)
- The energy is absorbed when it hits the surface of the earth
- The surface of the earth radiates energy as long wavelength radiation
- Some of the energy from the long wavelength radiation is reradiated by greenhouse gases . Because the energy is reradiated in the atmosphere this causes the temperature of the atmosphere to increase.
Why is the greenhouse effect important
The greenhouse effect is important as without it the earth would be too cold for organisms to survive
Why are carbon dioxide levels increasing in the atmosphere
- Carbon dioxide levels are increasing because of increased burning of fossil fuels
- Carbon dioxide levels are also increasing because of deforestation. Trees absorb carbon so clearing them releases this carbon back into the atmosphere
Why are methane levels increasing
- Methane levels are increasing because of increasing agriculture. Agriculture releases methane e.g growing rice in flooded rice paddies
- Methane levels are also increasing because of increases in cattle farming. Cows release methane when they pass gas
What affect are the increased greenhouse gas levels having on the atmosphere
Increased greenhouse gas levels are increasing the temperature of the earth as they are causing more energy from the sun to be trapped in the atmosphere
What affects is the rising temperature having
- Rising temperature will increase the melting of polar ice sheets and glaciers. This increases sea level. The increasing sea level could flood low lying areas
- Rising temperatures could also lead to more extreme weather events e.g more storms in the UK
- Rising temperatures could also lead to animals becoming extinct
What is peer review
Peer review is where scientists critisize each others conclusions and evidence and decide wether it is valid or not.
Why is climate change difficult to predict
- Climate change is difficult to predict as it is compex and hard to model
- There is also lots of uncertianty around climate change e.g it is difficlut to predict how much the temperature of the atmosphere will increase
What is a carbon footprint
A carbon footprint is the total amount of carbon dioxide and other gases emitted during the total life cycle of product,service or event
What are three ways carbon dioxide emissions can be reduced
- Carbon dioxide emissions can be reduced by insulating homes and turning down the heating as a lot of energy is used heating homes
- Carbon dioxide emissions can also be reduced by taking public transport instead of driving as a great deal of c02 is released driving
- Carbon dioxide emissions can be reduced by generating electricity from renewavle sources as generating electricity by burning fossil fuels releases lots of greenhouse gases
What are two ways methane emissions can be reduced
- We can reduce methane emissions by reducing the amount of dairy and meat we consume. This will reduce cattle grazing which is a main source of methane emmisions
- We can also reduce methane emmisions by trapping methane released from landfill and burning it to generate electricity
What is complete combustion
Complete combustion is where fuels burn in plenty of oxygen to produce carbon dioxide and water vapour
What is incomplete combustion
Incomplete combustion is where fuels burn but there is not enough energy so the feuls produce carbon monoxide instead of carbon dioxide
What is carbon monoxide
Carbon monoxide is a toxic gas with no odour that binds to haemoglobin and reduces oxygen flow in the body
What happens when fuels containing sulfur are oxidised
Some fuels e.g coal contain the element sulfur. When the feuls are burnt and oxidised they produce sulfur dioxide
How are oxides of nitrogen produced
Oxides of nitrogen are produced inside engines e.g car engines
-There , high temperature cause nitrogen and oxygen from the air to react to form oxides of nitrogen
What are the effects of sulfur dioxide and oxides of nitrogen
- Both sulfur dioxide and oxides of nitrogen cause breathing problems in humans
- They also both dissolve in rainwater to form acid rain which damages trees and corrodes limestone buildinhs
What are particulates
Particulates are particles of carbon and unburnt hydrocarbons
What are problems caused by particulates
- Particulates cause damage to human health and cause heart and lung disease
- Particulates also reduce the amount of energy from the sun reaching the earths surface which causes global dimming
How is limestone formed
Limestone is formed from calcium carbonate deposits in the shells of marine organims
