The earth atmosphere Flashcards
200 million years, the proportions of different gases in the atmosphere have been much the same as they are today:
about four-fifths (approximately 80%) nitrogen
* about one-fifth (approximately 20%) oxygen
* small proportions of various other gases, including carbon
dioxide, water vapour and noble gases.
Theories about what was in the Earth’s early atmosphere and how the atmosphere was formed have changed and developed over time.
during the first billion years, there was lots volcanic activity that released gases that formed the early atmosphere and water vapour that condensed
to form the oceans. At the start of this period consisted of mainly carbon dioxide with little or no oxygen gas.
Volcanoes also produced nitrogen which gradually built up in the atmosphere and there may have been small proportions of methane and ammonia.
How was carbon dioxide reduced?
When the oceans formed carbon dioxide dissolved in the water and carbonates were precipitated producing sediments, reducing the amount of carbon dioxide in the atmosphere. Algae and plants decreased the percentage of carbon dioxide in the
atmosphere by photosynthesis.
Carbon dioxide was also decreased by the formation of
sedimentary rocks and fossil fuels that contain carbon
How was oxygen increased?
Algae and plants produced the oxygen that is now in the
atmosphere by photosynthesis. Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere. Over the next billion years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve.
what are greenhouse gases?
Water vapour, carbon dioxide and methane are greenhouse gases. Greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life.
what human activities increase the greenhouse gases?
burning fossil fuels
deforestation
farming cattle
what are four potential effects of global climate change?
ice caps to melt and consequently, polar bear habitats are shrinking
sea levels rising - floods
loss of habitat
wild fires
crop failure.
what is a carbon footprint?
The carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
how can the carbon footprint be reduced?
The carbon footprint can be reduced by reducing emissions of
carbon dioxide and methane.
what gases are released when a fuel is burned?
The gases released into the atmosphere when a fuel is burned may
include carbon dioxide, water vapour, carbon monoxide, sulfur dioxide and oxides of nitrogen. Solid particles and unburned hydrocarbons may also be released that form particulates in the
atmosphere.
what is carbon monoxide?
Carbon monoxide is a toxic gas. It is colourless and odourless and so is not easily detected.
what does sulfur dioxide cause?
Sulfur dioxide and oxides of nitrogen cause respiratory problems in
humans and cause acid rain.
what does sulfur dioxide and carbon monoxide particles cause?
Particulates cause global dimming and health problems for humans.
