Weather, Hazards and Climate Change Flashcards
How does the greenhouse effect work?
- The sun’s rays (visible light) enter the atmosphere and are absorbed by the earth.
- Some of the sun’s rays are reflected off the earth’s surface (still visible light) and pass out through the earth’s atmosphere back into space.
- However, the earth also re-radiates some of the light energy it absorbed back into space as infrared radiation (heat).
- Greenhouse gases, like carbon dioxide and methane, act like a blanket around the earth and absorb some of the infrared radiation.
- The greenhouse gases re-radiate the absorbed infrared radiation in all directions. Some of this is
radiated back towards earth. - This causes the atmosphere to become warmer.
evidence for natural climate change
- ice cores
- tree (growth) rings
- historical records
- pollen
evidence for natural climate change: ice cores
Analysis of the gas trapped in the layers of ice from locations such as Antarctica tell us what the temperature was like each year. This is because they contain microbes, volcanic ash and bubbles of air. Scientists can then determine the amount of CO2 in the atmosphere to know the temperature.
evidence for natural climate change: tree rings
As a tree grows it forms a ring. Growth rings tend to be wider in warmer, wetter climates and thinner and colder, drier climates. Therefore, by counting the rings they can figure out how old a tree is and by looking at the width they could tell the climate of a particular time.
evidence for natural climate change: historical records
We can examine representations of the climate from personal diaries and religious records and compare them to the climate in that place today. e.g logs collected on ships, by farmers monitoring crops, personal diaries, religious records, paintings. e.g. painting: grape harvests in Paris (1370-1879), and Thame Frost fairs in the 1600s.
evidence for natural climate change: pollen records
We can identify and date pollen preserved in sediment. This tells us the type of plants that were able to grow at a particular point in history. This shows what the climate was like at that time in that place.
What are the features of the global atmospheric circulation (GAC) ?
- Redistribution of heat from the equator to the poles
- Jet streams impact on the movement of air
- Jet streams usually form at the boundaries of the main circulation cells
- Spin of the earth creates the Coriolis effect
- Each cell moves in a circular motion due to the Coriolis effect
How do the circulation cells in the GAC model work?
At the equator, warmed air rises causing low pressure. The air cools and condenses as it rises to form clouds. This means TRF forms at equator due to warm temperature of sun and high rainfall.
The air current divides, cools and moves north and south to form Hadley Cells. The cooled air sinks at 30° north and south of the equator, leading to high pressure. As the cool air sinks it gets warmer, leading to a warm and dry climate at the tropics (hot desert forms here).
Some of the cooled air moves back towards the equator as trade winds. The rest travels towards the poles. (forming the lower part of the Ferrel Cells).
At 60° north and south, the warmer air of those cells meets colder polar air. The warmer air rises to form Polar cells. This air travels to the poles where it cool and sinks, forming areas of high pressure.
What are jet streams?
They are fast-flowing, narrow meandering air currents found in the atmosphere. they flow from west to east due to the rotation of the earth.
If the polar front jet is situated significantly to the south of the UK, we experience colder weather and if its situated to the north of the UK, we experience warmer weather.
Negative effects of climate change on the environment and people
- Changing patterns of crop yields
- Rising sea levels
- Retreating glaciers
Negative effects of climate change: Changing patterns of crop yields
- Warmer temperatures can lead to more frequent droughts and lower crop yields.
- Demand for wheat is rising yet Global crop yields are declining»_space; famine and malnutrition especially in developing countries because they can’t afford to import food/goods
- if temperatures rise by 1.5°C, rice yields globally may drop by more than 5.5%
Negative effects of climate change: Rising sea levels
- Land based ice melting and thermal expansion»_space; sea level rise which will affect 80 million people.
- Sea level rise can also lead to greater coastal erosion and risk of flooding in coastal areas. Low lying island nations like the Maldives are particularly vulnerable
- the Maldives are all under 2.4m above sea level. so even, small amounts of sea level rise of 0.2-1m will cause flooding
Negative effects of climate change: Retreating glaciers
- Melting of glaciers at the poles could also affect the ocean currents and redistribution of heat around the earth
- Glaciers provide water for important rivers like the Ganges.
- Short –term»_space; flooding. Long term»_space; rivers to dry up and ecosystems to be lost
- Matterhorn in Switzerland: by 2100, 90% of ice could be gone
- reduced albedo effect: no more white snow/ice on mountains which normally reflects sun rays back into the atmosphere. If there is no ice, rocks absorb the suns rays»_space; ice melts.
- temperature increases»_space; ice contains methane»_space; when it thaws, methane (a greenhouse gas) is released»_space; contributes to EGHE»_space; heats earth»_space; more ice melts»_space; more methane released & cycle continues
What is the Climate of the UK today?
- The UK has a temperate climate.
- Extremes of weather are uncommon and extreme weather events are rare.
- Temperature and precipitation do not have extremes
- Annual temperature and precipitation range is small.
Factors that affect the UK climate
- latitude
- air masses
- continentality (distance from the sea)
- ocean currents
