Unit 2 - Global Climate - Vulnerability and Resilience Flashcards
What does the atmosphere consist of and how big is it?
- mixture of solids, liquids and gases
- up to a height of around 80km
- consists of nitrogen, oxygen, argon and a variety of other trace gases such as carbon dioxide, helium and ozone - also water vapour and solids such as dust, ash and soot
How does temperature vary in the atmosphere?
- temperatures fall with height
What is the atmosphere?
- an open energy system receiving energy from both the Sun and Earth
What is insolation (atmosphere)?
- incoming solar radiation
What does solar energy drive?
- all weather systems and climate
What is radiation?
- the emission of short waves and long waves; as the Sun is a very hot body, most of its radiation is in the form of very short wavelengths such as ultraviolet and visible light
What is convection?
- the transfer of heat by the movement of a gas or liquid
What is conduction?
- the transfer of heat by contact
What happens to the solar energy?
- 46% is absorbed by the earth
- 22% drives the hydrological cycle
- 1% powers the winds and ocean currents
- 31% is reflected into space
What happens to the short-wave radiation (46 units) that reaches the ground?
- 14 are re-radiated as long-wave radiation to the atmosphere and to space
- 10 units pass to the atmosphere by conduction or the lower atmosphere only - since air is a poor conductor of heat
- 22 units are transferred by latent heat - the heat energy used by a substance change form but not temperature
From where is the atmosphere largely heated?
- from below
What is the greenhouse effect?
- most of the incoming short-wave radiation is let through the atmosphere, but CO2 traps the outgoing long-wave radiation, warming the atmosphere
What does the amount of insolation the Earth receives depend on?
- angle of the Sun (high - more solar radiation)
- type of cloud type (far from Earth and/or thin/no clouds - more solar radiation)
What does long-wave radiation refer to?
- the radiation of energy from the Earth into the atmosphere
What is the greenhouse effect?
- the process by which certain gases (greenhouse gases) allow short-wave, solar radiation to pass through the atmosphere but trap a proportion of outgoing long-wave radiation from the Earth
Why is the greenhouse effect a good thing?
- without it, there would be no life on Earth
How much have carbon dioxide levels risen from 1950 to 2015?
- have risen from 315ppm to 400pm
- are predicted to reach 600pm by 2050
What is the most common greenhouse gas?
- water vapour
- accounts for about 95% of greenhouse gases by volume and for about 50% of the natural greenhouse effect
What is the increase in carbon dioxide levels caused by?
- due to human activities, such as burning fossil fuels and land-use changes such as deforestation
How much does carbon dioxide account for in the greenhouse effect?
- 20%, but an increased proportion of the enhanced greenhouse effect
What is the second-largest contributor to global warming?
- Methane
- its presence in the atmosphere is increasing at a rate of 1% per annum
How much methane do cattle emit into the atmosphere per year?
- 100 million tonnes a year
- cattle convert up to 10% of the food they eat into methane
How much methane do paddy field emit into the atmosphere per year?
- 150 million tonnes a year
What are chlorofluorocarbons (CFCs)?
- man-made chemicals that destroy ozone as well as absorbing long-wave radiation
- increasing at a rate of 6% per annum
- up to 10,000 times more efficient at trapping heat than CO2