Atmosphere Flashcards
What is the composition of atmospheric gases?
- 80% Nitrogen
- 20% oxygen
- small proportionso of other gases
When did the Earth form?
4.6 billion years ago
What planets did Earth have a similar atmosphere to 4.6 billion years ago?
what was there?
mars or venus
carbon dioxide, little or no oxygen gas
Why is evidence for the early atmosphere limited?
- long time scale
How did the early atmosphere form?
- volcanic activity released water vapour + CO2
- earth cools, condenses water vapour (fell as rain -> oceans)
- CO2 dissolved in oceans
- nitrogen released from volcanoes
- unreactive, builds up
- small proportions of methane and ammonia
How was nitrogen produced in the early atmosphere?
- produced by volcanoes
- dentitrifying bacteria produced nitrogen
- ammonia reacted with oxygen
How did carbon dioxide decrease?
- carbon dioxide dissolved in ocean
- sedimentary rocks made from carbonate ions released by CO2, react with metals to form insoluble carbonates
- coal formed from plant deposits, buried + compressed
- crude oil + natural gas = plankton deposited in mud on sea floor, covered, compressed
- algae and plants photosynthesised
How did oxygen increase?
- algae first produced oxygen at 2.7 billion years ago
- next billion years plants evolved
- O2 percentage increased until animals can evolve
What is the equation for photosynthesis?
6CO2+6H2O→C6H12O6+6O2
What would happen if the greenhouse effect does not exist?
Earth would be too cold for life to exist
What do greenhouse gases include?
- water vapour
- carbon dioxide
- methane
Describe the greenhouse effect
1) energy transmitted from sun to earth by radiation
2) some radiation reradiated to space by earth’s atmosphere, clouds nad surface
3) remaining radiation absobed by earth’s surface, warming it up
4) warm surface emits radiation, warms atmosphere
5) greenhouse gases in atmosphere absorb radiation
6) absorbed radiation radiated in all directions, keeping atmosphere and surface warm
short wavelength radiation passes through atmosphere
long wavelength absobed
What human activities contribute to the increase of CO2?
- burning fossil fuels
- deforestation
What human activities contribute to the increase of methane?
- cattle farming
- rice fields
- decomposition of rubbish in landfill
What are the impacts of climate change?
- more heat waves
- fewer cold periods
- more droughts/ rainfall in some places
What is carbon footprint?
- total amount of greenhouse gases released over the lifetime of a event or product
How can we reduce our carbon footprint?
- walk or cycle instead of driving
- eat less meat
- increase recycling
- alternative forms of energy
What are the most common atmospheric pollutants?
- Carbon monoxide (CO)
- Sulfur dioxide (SO2)
- Nitrogen oxides (NOx)
- particulates (C)
How is carbon monoxide produced?
- imcomplete combustion of a hydrocarbon fuel
How is sulfur dioxide produced?
- burning coal or petrol
- contains sulfur, reacts with oxygen in air
How are nitrogen oxides produced?
- in car engines
- N2 and O2 in air react in high temps
How are particules produced?
- incomplete combustion of a hydrocarbon fuel
What is the effect of carbon monoxide?
- toxic gas
- colourless and odourless, hard to detect
What are the effects of sulfur dioxide and nitrogen oxides?
- causes respiratory problems
- combines with water vapour to cause acid rain
What are the effects of particulates?
- global dimming
- can damage lung cells
