Atmosphere Flashcards
How do scientists know the historic composition of the air
- by analysing the tiny air bubbles trapped in ice cores taken at the poles
- the air bubbles were trapped as the snow and ice was laid down tens of thousands of years ago
Evolution of the atmosphere
- the surface of the early Earth was molten and there was no atmosphere surrounding the planet
- cooling began to take effect and allow for molten materials to slowly solidify forming land masses
- volcanoes formed on the land masses
- the volcanoes released gases from the Earth’s interior through violent eruptions
- the eruptions released large amounts of carbon dioxide and water vapour, as well as nitrogen, hydrogen, and other gases
- Earth’s gravity prevented the gases from escaping into outer space and they formed the early atmosphere
- the early atmosphere, therefore, is thought to have contained mainly CO2 and water vapour
-> there was little or no oxygen present
How the oceans formed
- when conditions cooled sufficiently, the water vapour later condensed and fell to the surface of the Earth, forming the oceans
- when the water vapour condensed large amounts of CO2 dissolved in the oceans
How oxygen increased
Primitive plants and algae began photosynthesising which used up carbon dioxide from the atmosphere and released oxygen
How carbon dioxide decreased
- the water vapour in Earth’s early atmosphere condensed large amounts of CO2 dissolved in the oceans
- carbonates were precipitated during this process which later formed sediments on the seabed
- green plants and algae began to evolve and absorbed considerable amounts of carbon dioxide during photosynthesis
- animals fed on the plants which transferred carbon to their tissues including bones and shells
- when these organisms died, their remains formed sedimentary rocks
->the formation of sedimentary rock and fossil fuels ‘locked up’ the carbon from carbon dioxide in the early atmosphere
Explain the greenhouse affect
- short wavelength radiation from the sun is absorbed by the earths surface and re-emitted from the surface of the Earth as infrared radiation which has a longer wavelength
- but a lot of the radiation is absorbed in the Earth’s atmosphere by greenhouse gases
Name the greenhouse gases
- carbon dioxide
- methane
- water vapour
Effects of global climate change
- rising sea levels
- extinction of species
- migration
- decrease in crop yield
Carbon footprint
The total amount of CO2 and other greenhouse gases emitted over the full life cycle of a product
Human activities that increase greenhouse gases in the atmosphere
- driving
- consuming electricity
- decay of waste in landfill sites
- raising livestock
Life Cycle Assessment
A technique used to assess the environmental impact associated the life cycle of a product, a service or an event
What is the major source of atmospheric pollution
The combustion of fossil fuels
Combustion and incomplete combustion products
- the burning of fossil fuels releases the gases carbon dioxide, carbon monoxide, nitrogen oxides and sulfur oxides
- incomplete combustion of the fuels gives rise to unburned hydrocarbons and carbon particulates
What is formed when hydrocarbons are used as a fuel
Water and carbon dioxide
Incomplete combustion
Occurs when there is insufficient oxygen to burn
