C14 The Earth’s Atmosphere Flashcards
What is the atmosphere?
A layer of gas surrounding the earth
What was the early atmosphere composed of?
Mostly CO2
Little oxygen nitrogen and water vapour
How did oceans form?
Water vapour condensing as the earth cooled
How did the amount of CO2 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?
About 2.7 billion years ago
The 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
Y 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?
Approximately 80% nitrogen, 20% oxygen, and trace amounts of other gases such as CO2, 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 wavelength
Name three greenhouse gases
Methane 🐄
Carbon dioxide 🚘
Water 🌊 vapour
Give two ways recent human activities have increased the amount of atmospheric carbon dioxide
Burning fossil fuels
Deforestation
Give two ways recent human activities have increased the amount of atmospheric methane
Rice farming
Cattle farming
Global warming?
An increase in the overall global average temperature 🤒
What is global climate change
The change in long-term weather patterns across the planet
