The Earths atmosphere Flashcards
What is the atmosphere?
A layer of gas surrounding the earth
What was the early atmosphere composed of?
Mostly carbon dioxide
How did the oceans form?
Water vapour condensing as the Earth cooled
How did the amount of carbon dioxide in the atmosphere decrease to today’s levels?
Dissolved in the oceans, photosynthesis, converted to fossil fuels, precipitated as insoluble metal carbonates
When did life start to appear, and what was the impact of this on oxygen in the atmosphere?
2.7 billion years ago
Amount of atmospheric oxygen increased as it was released in photosynthesis
How has the amount of nitrogen in the atmosphere changed over time?
Increased slowly as it is a very stable molecule
Why can scientists not be sure about the composition of the Earth’s early atmosphere?
It was billions of years ago and evidence is limited
What is the current composition of the atmosphere?
aprox 80% nitrogen, 20% oxygen
Trace amounts of carbon dioxide, water vapour and noble gases
What is a greenhouse gas?
A gas that traps radiation from the sun
What type of radiation do greenhouse gases absorb?
Longer wavelength infrared radiation
Name three greenhouse gases
Methane
Carbon dixoide
Water vapour
Give two ways recent human activity has increased carbon dixoide levels
Burning fossil fuels
Deforestation
Give two ways recent human acitivites have increased the amount of atmospheric methane
Rice farming
Cattle farming
Define global warming
Increase in overall global average temp
What is global climate change?
Change in long term weather patterns across the planet
Some possible effects of climate change
Sea levels rising Extreme weather events Changes in amount and time of rainfall Polar caps melting Changes to ecosystems
Define carbon footprint
Amount of carbon a product/process/person releases into the atmosphere over its lifetime
How is carbon monoxide formed, why is it dangerous?
Incomplete combustion
Colourless and odourless toxic gas
How are particulates formed and what are the dangers associated with them?
Incomplete combustion
Global dimming, respiratory problems, potential to cause cancer
How is sulfur dioxide formed and what are its dangers?
Sulfur impurites in fossil fuels react with oxygen during combustion
Acid rain, respiratory problems
How are oxides of nitrogen formed and what are the dangers associated with them?
Atmospheric oxygen and nitrogen react in the heat of a combustion engine
Acid rain, respiratory issues
