c13 the earth's early atmosphere Flashcards
composition of nitrogen
about 4/5 (80%)
composition of oxygen
1/5 (20%)
small proportions of various gases include?
carbon dioxide, water vapour and noble gasses
why is evidence for the early atmosphere limited?
because of the time scale of 4.6 billion years
during the first billion years of the Earth’s existence, what was there?
during the first billion years of the Earth’s existence, there was intense volcanic activity that released gases that formed the earths early atmosphere
what happened to water vapour?
water vapour condensed to form the oceans
at the start of this period, the Earth’s atmosphere may have been like the atmosphere of?
mars and venus today, consist of mainly carbon dioxide with little or no oxygen gas
what do volcanoes also produce?
nitrogen which gradually built up in the atmosphere
there may have also been small proportions of ?
methane and ammonia
what happened when oceans formed?
carbon dioxide dissolved in the water and carbonates were precipitated producing sediments, and reducing the amount of carbon dioxide in the atmosphere
the earth’s early atmosphere was formed by and consisted mainly of?
volcanic activity and consisted mainly of carbon dioxide
as plants spread over the earth, what happened to the levels of oxygen in the atmosphere?
it increased
what produced the oxygen that is now in the atmosphere?
algae and plants by photosynthesis
when did algae first produce oxygen?
about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere
over the next billion years plants evolved and what happened?
the percentage of oxygen gradually increased to a level that enabled animals to evolve
what decreased the percentage of carbon dioxide in the atmosphere?
algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis
what else decreased carbon dioxide?
the formation of sedimentary rocks and fossil fuels that contain carbon
what do greenhouse gases in the atmosphere do?
greenhouse gases maintain temperatures on Earth high enough to support life.
what are examples of greenhouse gases?
water vapour, carbon dioxide,and methane
what does energy from the sun travel to the earth as?
short wavelength radiation e.g ultraviolet and visible light
what happens to some of the short-wavelength radiation?
simply reflects back into space but most of it passes easily through the atmosphere
why does this happen to some of the short-wavelength radiation?
because short-wavelength radiation does not react strongly with the gas molecules in the atmosphere
when is the energy of the radiation absorbed?
when it reaches the surface of the earth
the surface of the earth now radiated the energy as ?
long wavelength radiation such as infrared
what do some of the long wavelength radiation interact with?
greenhouse gas molecules in the atmosphere - the energy in the long wavelength radiation is absorbed
because the energy is trapped in the atmosphere what does this cause?
the temperature of the atmosphere to increase
what does the greenhouse effect do?
it keeps the temperature on earth warm enough to support life
without the greenhouse effect what would happen?
the earth would be too cold for most living organisms to survive
carbon dioxide increases as
we burn fossil fuels example we burn coal for electricity and gas to heat our homes
what is carbon dioxide absorbed by?
growing trees, but burning forests releases a lot of carbon dioxide
what is methane released in?
agriculture e.g growing rice in flooded paddy fields and when cows pass wind
based on peer reviewed evidence, what do many scientists believe?
human activities will cause the temperature of the earth;s atmosphere to increase at the surface and that this will result in global climate change
what is a major cause of climate change?
an increase in average global temperature
rising temperatures will increase?
melting of the polar ice sheets and glaciers. This will lead to increase sea levels.
Give one reason why it is difficult to produce models for future climate change.
-complex systems
* many different variables
* many alternative theories
Describe how carbon dioxide helps to maintain temperatures on Earth.
carbon dioxide allows short-wavelength radiation to pass through
allow greenhouse gas(es) for carbon dioxide
the atmosphere to the Earth’s surface
carbon dioxide absorbs outgoing long-wavelength radiation
what is the carbon footprint?
are the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product service or event
the carbon footprint can be reduced by reducing emission of
carbon dioxide
the combustion of fuels is ?
a major source of atmospheric pollutants
