The Atmosphere

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  • Created by: Morgan.K
  • Created on: 12-06-18 16:10

The Atmosphere Today...

80% Nitrogen

20% Oxygen

0.04% Carbon Dioxide

This has stayed constant for around 2million years!

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The Earths 4600millionth birthday!!

The Earth is around 4600million years old. This means that scientists cannot be certain about what the early atmosphere is like.

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The Earths Atmosphere in the First Billion Years

There was intense volcanic activity.

The volcanoes release many gases including water vapour. This water vapour cooled and condensed to form the oceans.

They also released a lot of Carbon Dioxide. This meant that the atmosphere was mainly Carbon Dioxide, with very little oxygen present.

Volcanoes also released nitrogen, which built up in the atmosphere over time, along with small amounts of methane and ammonia.

The Earths atmosphere in the first billion years was much like the atmosphere on Mars or Venus today.

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The Differences between Early and today's Atmosphe

  • Nitrogen has increased massively.
  • Carbon Dioxide has decreased massively
  • Today's atmosphere contains much more oxygen.
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What caused the changes in the Atmosphere?

  • Some carbon dioxide dissolved in the oceans to form a weak acid. This then reacted with the minerals in the sea to form precipitates. Over time this formed the sediment of carbonate rock on the seabed. Some of the carbon dioxide in the sea was also used to make corals and shells of organisms such as muscles.
  • When organisms like muscles died in the ocean, it helped form limestone. This also removed carbon dioxide from the atmosphere.
  • 2.7 billion years ago, photosynthetic algae first evolved in the oceans. They carried out photosynthesis which produced oxygen.
  • The carbon from photosynthesis can be trapped in fossil fuels and again caused the levels of carbon dioxide to drop.
  • Over billions of years, plants evolved and the levels of oxygen in the atmosphere began to rise.
  • Animals began to evolve due to the rise in oxygen levels.
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Fossil Fuels

  • They are formed over millions of years.
  • They are non-renewable and will eventually run out.
  • Coal is formed from the remains of ferns and trees. If they die in marshy wetlands then they do not decompose. This is either due to the lack of oxygen or the acidic conditions, as they stop bacteria from carrying out decomposition. Over time the plant remains are covered with sediment and compressed. The high temperatures and pressures create coal.
  • Crude oil is formed from plankton which are tiny plants and animals found in the sea. When they die they settle in mud on the sea-bed. They will not decompose if oxygen is not present. Over time, they are compressed by sediment. Heat and pressure then convert them into crude oil.
  • Natural Gas is mainly the hydrocarbon methane. We find it near deposits of oil. This is because it is formed from plankton in a similar way to oil.

All fossil fuels contain trapped carbon and that carbon was part of the carbon dioxide taken in by photosynthesis.

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The Greenhouse Effect

Greenhouse gases include - 

  • Carbon Dioxide
  • Methane
  • Water Vapour
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The Greenhouse Effect

  • Short wavelength radiation travels from the Sun to Earth. (Ultraviolet and Visible Light)
  • Most of these waves just reflect off the surface of the atmosphere, but some pass easily through it. This is because short wavelengths do not interact strongly with the gas molecules in the atmosphere.
  • The energy of the radiation is absorbed when it reaches the surface of the Earth.
  • The surface of the Earth now radiates the energy as long wavelengths such as infra-red.
  • Some of this radiation interacts with the greenhouse gases in the atmosphere.
  • The energy of the longwave radiation is absorbed.
  • Because this energy is trapped in the atmosphere, this causes the temperature of the atmosphere to increase.

The greenhouse effect keeps the Earth warm enough to sustain life. Without it, the Earth would be too cold for organisms to live on.

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Climate Change

  • The levels of Carbon Dioxide in the atmosphere are incfeasing due to human activity, Like burning fossil fuels like coal for electricity and petrol/diesel to power cars.
  • Normally carbon dioxide is absorbed by growing trees, but due to deforestation carbon dioxide is being released.
  • Methane is released when cattle pass wind. 
  • The more carbon dioxide and methane being produced mean more energy is being trapped in the atmosphere, warming it up.
  • Rising temperatures will increase the melting of polar ice sheets and glaciers. This will further increase sea levels.
  • With these increased sea levels comes more flooding.
  • Also, many places will experience more severe weather.
  • It could also change the distribution of animals such as insects and some diseases carried by insects.
  • Climate change is complex and difficult to model.
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Carbon Footprint

The carbon footprint tries to give us an idea of how much something contributes to climate change. It is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.

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Ways to Reduce Carbon Footprint

  • Insulate your home.
  • Turn down the heating.
  • Use public transport.
  • Use renewable sources of electricity.
  • Use energy saving bulbs.
  • Turn appliances off at the plug.
  • Eat less beef and dairy products.
  • Trap methane from landfill and burning it for electricity.

However, most of these methods are expensive and inconvenient.

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What are Fuels?

Fuels are chemicals that release energy when they are combusted.

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Fuels

Most fuels contain hydrogen and carbon. When we burn fuels, the carbon and hydrogen atoms react with the oxygen in the air.

Some fuels such as coal contain sulphur. These sulphur atoms are oxidised. This produces sulphur dioxide.

Oxides of nitrogen are produced inside engines. High temperatures cause nitrogen and oxygen to react. Both can cause acid rain and breathing problems.

Particulates are tiny particles produced during combustion. It causes global dimming as the suns energy struggles to reach the earth surface. Global dimming is affecting rainfall patterns.

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