Topic 1 - Hazardous Earth Flashcards
Low pressure
The air rises and cools, condenses and forms clouds. This means that there is rain and it’s unstable.
High pressure
The air is sinking which means that there is clear sky and no rain and it’s stable.
Weather at different parts of the planet?
1 (on the equator) = This area is very hot and very wet.
2 = This area is very hot and very dry. Dessert.
3 = This area is mild (not to hot or cold) and wet. Temperature, mid latitudes.
4 = This area is very cold and very dry. North Pole, Polar climate.
Why does the sun heat the Earth’s surface unevenly?
• The earth receives most radiation on the equator where it is hottest compared to the poles where it is coldest.
• The equator receives the most radiation because the sun rays hit the surface a right angle.
• At the poles, the curvature of the earth means that the angle is much lower which means they have to heat up a much larger area.
• At the poles the atmosphere is thicker so the radiation has to get through a bigger atmosphere.
How do winds transfer heat from the equator to the poles?
• The differences in temperature cause differences in air pressure.
• Winds blow from the areas of high pressure to the areas of low pressure.
• The earth is constantly rotating and deflects winds to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
• This transfers heat away from the equator.
What are the 3 cells in each Hemisphere?
Polar Cell
Ferrel Cell
Hadley Cell
Global atmospheric circulation
1) At the equator the sun warms the earth, which transfers heat to the air above, causing it to rise. This creates a low pressure belt. As the air rises, it cools and condenses forming clouds and rains.
2) The cool, dry air moves out to 30° north and south of the equator.
3) At 30° north and south of the equator, the cool air sinks, creating a high pressure belt with cloudless skies and very low rainfall.
4) The cool air reaches the ground surface and moves back to the equator as trade winds.
Rising air cannot hold as much moisture that’s why there is more precipitation on the equator.
5) At 60° North and South of the equator, the warmer surface winds meet colder air from the poles. The warmer air is less dense than the cold air so it is forced to rise, creating low pressure.
6) Some of the air moves back to the equator, and the rest moves towards the poles.
7) At the poles the cool air sinks, creating high pressure.
Ocean currents
Ocean currents are large scale movements of water that transfer heat energy from warmer to cooler regions
1) Some ocean currents are powered by winds resulting from the atmospheric circulation cells.
2) Others are powered by density differences due to differences in water temperature and salinity.
3) In the Arctic and Antarctic, the water gets very cold. This cold, salty dense water sinks.
4) As it sinks, warmer water from other laititudes is pulled in.
5) This is cooled to by the polar temperature and the cycle continues.
How does global atmospheric circulation determine the location of arid (dry) areas?
Sinking air from the Hadley and Ferrel cells meeting causes high pressure and prevents rainfall. Rainfall is very slow for all or most of the year. Temperatures are hot or warm.
How does global atmospheric circulation determine the location of tropical areas?
Rising air from the 2 Hadley cells meeting causes low pressure and lots of rainfall. Temperatures are hot all the time and rainfall is high.
How does global atmospheric circulation determine the location of polar areas?
Sinking air from the Polar cells creates an area of high pressure at the poles. Temperatures are low all year round and there’s very little rainfall.
ITCZ
• The inter tropical convergence zone. This is where trade winds meet and air is heated so it rises.
• When air rises, it cools and condenses to form clouds and rain.
• The ITCZ migrates North in summer and South in winter. It brings the areas north and south of the equator a wet season. When it migrates away, it creates a dry season.
What is the quaternary period?
• This is the most recent geological period of time spanning from 2.6 million years ago to the present day.
• In the period of time before this the Earth was warmer and stable, however then things changed.
• During the quaternary period the Earths global temperature fluctuated between Inter glacial periods (warm) and Glacial periods (cold/ice ages).
• The last Glacial period ended around 15,000 years ago since then the Earth has been warming.
4 natural causes of climate change?
- Orbital changes
- Volcanic Activity
- Solar output
- Asteroid collisions
Orbital changes
1) Orbital changes are variations in the way the Earth moves round the sun.
• Stretch - the path of the Earth’s orbit around the sun changes from an almost perfect circle to an eclipse (an oval) and back again.
• Tilt - the Earth’s axis is tilted at an angle as it orbits the Sun. This tilt changes over a cycle.
• Wobble - the axis of the Earth Wobbles like a spinning top on a cycle of about 22,000.
2) These cycles affect the amount of solar radiation (energy) the Earth receives. If the Earth receives more energy, it gets warmer.
3) Orbital changes may have caused the glacial and interglacial period of the Quaternary period.
Volcanic activity
1) Major volcanic eruptions eject large quantities of material, e.g. ash, into the atmosphere.
2) Some of these particles reflect the Sun’s rays back out to space, so the Earth’s surface cools.
Solar output
1) The suns output of energy isn’t constant.
2) Periods when solar output is reduced may cause Earth’s climate to become cooler.
Asteroid collisions
1) Asteroids hitting the earths surface can throw up huge amounts of dust into the atmosphere.
2) These particles prevent the suns energy from reaching the earths surface so global temperatures fall.
What evidence for Natural Causes of Climate Change is there?
- Tree rings
- Ice cores
- Historical data
Tree Rings
1) Most trees produce one ring within their trunks every year.
2) The thickness of the ring depends on the climate when the ring was formed - when it’s warmer the rings are thicker.
3) Scientists take cores through tree trunks then date each ring by counting them back from when the core was taken. By looking at the thickness of the rings, they can see what the climate was like each year.
Ice cores
1) Ice sheets are made up of layers of ice - one layer is formed each year.
2) Scientists drill into ice sheets to get long cores of ice.
3) By analysing the gasses (e.g. carbon dioxide) trapped in the layers of the ice, they can tell what the temperature was each year.
Historical data
1) Since the 1850s global temperatures have been measured accurately using thermometers. This gives a reliable but short-term record of temperature change.
2) Historical records (e.g. diaries and paintings) can extend the record of climate change a bit further back.
+ They are very detailed and can give an understanding of what the weather/climate was really like at the time. May also identify the impacts of this.
- The main drawbacks are that they were not written with the intention to record climate. Often info needs to be inferred. May be biased/exaggerated/made up. Lacks quantitative data.
Enhanced greenhouse effect
1) Solar radiation enters the atmosphere as short wave radiation. This easily passes through the atmosphere, as very little is absorbed.
2) Solar energy (radiation) is absorbed at the earths surface, and then radiates as long wave (infrared) radiation back into the atmosphere.
3) Long wave radiation is easily absorbed by the GHGs and so the heat becomes trapped, heating up the world.
4) Some long wave radiation escapes out of the atmosphere and into space.
5) Humans are releasing more greenhouse gases through the burning of fossil fuels. This is enhancing the natural process. Carbon dioxide is the most abundant GHG in the atmosphere.
Consequences of global warming
• Coastal flooding from sea level rises.
• More destruction from more frequent, stronger hurricanes.
• More droughts, longer lasting.
• More flood from more frequent, heavier precipitation.
• Biodiversity loss on land and in the oceans.
• Spread of pests and diseases.
• Changes in farming could affect food supplies.
Human activists making the greenhouse effect stronger
• Farming
• Industry
• Energy
• Transport
Farming
1) Farming of livestock produces a lot of methane - cows love to fart.
2) Rice paddies contribute to global warming, because flooded fields emit methane.
3) Trees absorb and store CO2. When land is cleared of trees for agriculture it stops the absorption of CO2, which leaves more CO2 in the atmosphere.
Industry
1) Most industry uses a lot of energy.
2) Some industrial processes also release greenhouse gasses.
3) Industrial waste may end up in landfill sites where it decays, releasing methane.
Energy
CO2 is released into the atmosphere when fossil fuels like coal, oil and natural gas are burnt.
Transport
1) Most cars, lorries, ships and planes run on fossil fuels, which release greenhouse gasses when burnt.
2) Car ownership is rapidly increasing in countries which are developing.
3) This means there are more cars on the road.
4) This increases congestion. As a result, car engines are running for longer, so the amount of greenhouse gases released increases.
Evidence that human activity is causing climate change
• Declining arctic ice
• Sea level rise and warming oceans
• Global temperature rise
• Extreme weather events
Declining Arctic ice
1) Sea ice forms around the poles in winter when ocean temperatures fall below -1.8°C and melts during summer when it’s warmer.
2) The extent of Arctic sea ice in winter has decreased by more than 3% each decade over the past 25 years.
Sea level rise and warming oceans
There are two factors behind this rise:
• Eustatic sea level rise - warmer temperatures are causing glaciers to shrink and ice sheets to melt. The melting of ice on land means that water stored on land as ice returns into the oceans. This causes sea levels to rise.
• Thermal expansion - water in the ocean expands as it gets warmer. Scientists think this accounts for about half of the measured rise in sea levels.
Extreme weather events
• Higher frequency of heat waves.
• Fewer cold weather extremes.
• In the Uk, more rainfall records where broken in 2010-2014 than in any decade on record.
Impacts of climate change one people
• Deaths due to heat have increased.
• Some areas could become so hot and dry that they’re difficult or impossible to inhabit.
• Low lying coastal areas could be lost to the sea or flood.
• Affecting farming.
• Lower crop yields — > Increase malnutrition, ill health and death.
• Weather is getting more extreme so more money has to be spent on predicting extreme weather events, reducing their impacts and rebuilding after them.
Scenarios for the range of projections for global temperature change and sea level rise.
• Scenario 1 - minimum emissions —> This is the best outcome in which levels of greenhouse gases peak, then reduce.
• Scenario 2 and 3 - Stabilising scenarios —> These are scenarios in which greenhouse gas levels continue to increase, but eventually level off (after steps are taken to reduce emissions)
• Scenario 4 - Maximum emissions —> This is the worst outcome, in which the rate of production of emissions continues to increase and greenhouse gas levels end up very high.
Why is it difficult to predict future climate change?
• Emissions - we don’t actually know how emissions will change. —> Preditions have to take into account things like population increase and economic development. It’s hard know how global population will change in the future or how much development will change.
• Complexity - we don’t know what exact climate changes each scenario will cause. —> There are lots of natural processes that we don’t fully understand, which makes it difficult to predict what will change. We don’t know how these natural factors could have an impact on climate change.
• Management - We don’t know what attempts there will be to manage the amount of greenhouse gasses in the atmosphere, and how successful they will be.
