Paper 1: Hazardous Earth - Topic 1 Flashcards
Where on the Earth’s surface receives the most radiation?
The earth is largely spherical so more radiation is recieved at the Equator, the hottest part of the earth whereas the poles are the coldest part. At the Equator, the sun’s rays are concentrated over a small area and strike at a right angle, meanwhile at the poles they reach the surface at a lower angle so the same radiation has to heat up a larger surface area. Also near the poles the radiation has had to pass through ‘more’ atmosphere and travel a greater distance so energy has been absorbed, meanwhile at the equator this is less.
What is meant by high and low pressure and why does this variation occur?
As heat rises, the lower atmosphere will have fewer particles, meaning less pressure. As the heat transfers, the atmosphere gets warmer and clouds form which is followed by rain falling. This is why rainfall means low pressure because there is less air on the surface, and more air up in the sky.
This is then the opposite for high pressure because when the aie sinks, the heat is transferred from the sky to ground level, meaning there are more particles, meaning more air and higher pressure. The air travels from low to high pressure due to atmospheric weight.
How does high and low pressure explain wind direction?
As the air moves up when going from high pressure to low pressure, and goes down when going from low to high pressure. Wind only occurs when air goes from high to low pressure across the Earth’s surface. However, the intended path that the air intends to take is not always followed due to the Coriolis Effect. The Coriolis Effect has an effect on the global circulation system, as the wind is pushed in different directions by the Earth’s rotation. Usually, the air in the North is pushed to it’s right, and the air in the South is pushed towards it’s left. (This is always in the direction of it’s travel so if it is going back towards the equator then this will not look the same from a bird’s eye view).
How do atmospheric circulation cells explain transfer heat energy around the world, as well show us where the High and Low Pressure belts are found?
The Atmospheric Circulation Cells distribute heat energy all over the globe. There are three different names of these cells, the: Hadley Cells, Ferrel Cells, and Polar Cells. The heat from the sun changes the air pressure and the air moves from high pressure areas to low pressure areas as surface winds, bringing the heat back to the equator. As a result the cells have high and low pressure belts. At 30° N and S, the cool air sinks, forming cloudless skies and High Pressure belts, but at 0° and 60° N and S, the warm air rises to create Low Pressure belts, meaning clouded ans possibly rainy weather.
How do large ocean currents transfer heat around the world?
1) Ocean currents are large scale movements of water that transfer heat energy from warmer to cooler regions
2) Surface currents are caused by winds and help transfer heat way from the Equator, e.g the Gulf Stream brings warm water from the Caribbean and keeps Western Europe warmer than it would otherwise be
3) There are also deep ocean currents driven by differences in water density.
4) When water freezes at the poles, the surrounding water gets saltier, increasing it’s density
5) As it gets denser, it sinks, causing warmer water to flow in at the surface - creating a current
6) This warmer water is cooled and sinks, continuing the cycle
7) This cycle of cooling and sinking moves water in a big loop round the Earth - this is known as the thermohaline circulation.
How Does Low Pressure Form?
When air is heated it rises as it is less dense. As it rises it transfers heat to the atmosphere. It cools, condenses and usually clouds and rain occurs.
Because there is ‘less air’ at the surface, it is now ‘low pressure’
How Does High Pressure Form?
When air cools it becomes more dense. It falls and as it does transfers heat to the ground. It warms as it falls leaving clear skies and little/no rainfall.
Because there is ‘more air’ at the surface, it is now ‘high pressure’
What order are which cell circulation systems around the world in, and where do the belts of low and high pressure lie?
The order is: (from equator outwards in North and South)
- Hadley Cell
- Ferrel Cell
- Polar Cell
Belts of Low Pressure are found:
- At 0°
- At 60° North
- At 60° South
Belts of High Pressure are found:
- At 30° North
- At 30° South
What are the 3 Circulation Systems?
- Hadley Cell
- Ferrel Cell
- Polar Cell
What does the Hadley Cell do?
The air separates and starts to move both north and south towards the poles.
When it reaches about 30° north and south, the air cools and sinks towards the ground forming the subtropical high-pressure zone.
As the air sinks, it becomes warmer and drier. This creates an area of little cloud and low rainfall, where deserts are found.
The Hadley cell is then complete. The air completes the cycle and flows back towards the equator as the trade winds.
In the northern hemisphere, the winds flow to the right and are called northeast trade winds. In the southern hemisphere the winds flow to the left and are called the southeast trade winds. This is down to the Coriolis force and friction.
(Goes Anti-Clockwise in the North, and Clockwise in the South, taking air from the Equator, up to around 30° North and South)
What does the Ferrel Cell Do?
Air on the surface is pulled towards the poles, forming the warm south-westerly winds in the northern hemisphere and north-westerly winds in the southern hemisphere.
These winds pick up moisture as they travel over the oceans. At around 60 degrees N and 60 degrees S, they meet cold air, which has drifted from the poles.
The warmer air from the tropics is lighter than the dense, cold polar air and so it rises as the two air masses meet.
This uplift of air causes low pressure at the surface and the unstable weather conditions that are associated with the mid-latitude depressions. Much of our wet and windy weather in the UK is determined by this.
(Travels the opposite way than the Hadley Cell, meaning it goes Clockwise in the North and Anti-Clockwise in the South. It takes air from 30° - 60°)
What does the Polar Cell Do?
At the poles, air is cooled and sinks towards the ground forming high pressure, this known as the Polar high. It then flows towards the lower latitudes. At about 60 degrees N and S, the cold polar air mixes with warmer tropical air and rises upwards, creating a zone of low pressure called the subpolar low. The boundary between the warm and cold air is called the polar front. It accounts for a great deal of the unstable weather experienced in these latitudes.
(This moves air in the same rotation as the Hadley Cell, going Anti-Clockwise in the North, and Clockwise in the South, taking air from the 60°, up to the Poles North and South).
What is Climate Change?
Climate change refers to how the average climatic conditions of the planet vary over time. The planet history is divided into periods and the climate during the Quaternary period (the last 2.6 million years) has changed many times. Global temperatures have shifted between cold glacial periods that last for around 100,000 years and warmer interglacial periods that usually last for around 10,000 years. The last glacial period ended around 15,000 years ago, since then the climate has been warming.
What are the Natural Causes of Climate Change?
- Orbital Changes (Eccentricity, Tilt/Obliquity and Precession (Wobble)
- Asteroid Collisions
- Volcanic Activity
- Solar Output Variation
What is Eccentricity (Stretch)?
Eccentricity is how the orbit of the Earth changes shape over long periods of time, approximately every 100,000 years. This means that sometimes the Earth’s orbit around the Sun is more circular, making us slightly warmer (interglacial), and sometimes the orbit becomes more elliptical, making the Earth slightly cooler (glacial).
What is Obliquity/Tilt?
Obliquity/Tilt is how the Earth does not sit with the North and South Poles exactly at the top and bottom of the planet. In fact, the Earth is tilted so that the poles are actually rotated approximately 23° from a vertical position. This creates our seasons north and south of the Equator. However, over a period of approximately 40,000 years, the angle of tilt changes. This means that sometimes the Earth is tilted further away the Sun, which makes the difference in the seasons more pronounced (summers are warmer and winters are colder). When it is tilted closer to the Sun, the difference in the seasons Is less.
How do Asteroid Collisions affect Climate Change events?
Large cosmic material, such as asteroids and comets, can impact the Earth’s surface.This can eject large volumes of dust into the atmosphere, partially blocking solar radiation and leading to glacial periods. Climate change that is caused by surface impact can have dramatic effects on life. One such impact approximately 65 million years ago is considered to be responsible for the extinction of the dinosaurs. It is not the force of the Impact that is thought to have wiped them out however, but rather the massive climate change that was created by the impact.
How does Volcanic Activity affect Climate Change events?
Big volcanic eruptions can change the Earth’s climate. Small eruptions have no effect - the eruption needs to be very large and explosive. Volcanic eruptions produce Ash and Sulphur dioxide gas.
If the ash and gas rise high enough, they will be spread around the Earth in the stratosphere by high-level winds. The blanket of ash and gas will stop some sunlight reaching the Earth’s surface. Instead, the sunlight is reflected off the ash and gas, back into space. This cools the planet and lowers the average temperature.
An example is:
(In 1991, Mount Pinatubo In the Philippines erupted, releasing 17 million tonnes of sulphur dioxide. This was enough to reduce global sunlight by 10%, cooling the planet by 0.5°C for about )
How do Variations in Solar Outputs affect Climate Change events?
Over 2000 years ago Chinese astronomers started to record sunspots. These are black areas on the sun’s surface (see Figure 1). Sometimes the sun has many spots, and other times they disappear. They tell us that the sun is more active than usual. Lots of spots mean more solar energy being fired out from the sun towards Earth.
Cooler periods, such as the Little Ice Age, and warmer periods, such as the Medieval Warm Period, may have been caused by changes in sunspot activity. Some people think that, on average, there were more volcanic eruptions during the Little Ice Age,and that this added to the cooling. However, climate change on timescales of a few hundred years, and 1- 2°C, cannot be explained by volcanoes - but it might be explained by sunspot cycles.
What is Precession (Wobble)?
As the Earth rotates on it’s axis(which is, of course, what gives us day and night), it does not do so perfectly. In fact, the Earth ‘wobbles’ on its axis, in a similar way to a spinning-top as it slows down.As this happens, the direction the axis is facing changes. This affects our seasons and creates either greater or smaller differences between summer and winter. This occurs over a period of approximately 24,000 years.
Evidences for Natural Climate Change:
- Tree Rings
- Ice Cores
- Historical Evidence
What can Tree Rings tell us?
- Each ring shows a year of growth. Changes in shape and size of tree rings can show conditions during that year.
- Warmer and wetter weather can show greater growth as the tree ring is bigger, cooler or drier weather can mean rings are thinner.
- On some trees there can be scarring from a forest fire, or where beetles and other insects have marked it
- Bigger rings mean rainy and warm seasons, while smaller rings mean cold and dry seasons.
What can Ice Cores tell us?
- The ice contains bubbles of the air from each year. Scientists analyse
the bubbles in each layer to see how much CO2 they contain. Scientists can also learn about the temperatures for each year by measuring relative amounts of different types of oxygen atoms in the water.
-Inside of the actual drilled piece of ice itself, you will find bubbles of Oxygen atoms and Carbon Dioxide in the atmosphere. Also, you can get a measure Pollution and Volcanic Ash over the years too.
What can Historical Evidence tell us?
- Old photos, drawings, written records, diaries and the records of dates at regular intervals e.g. the harvests, the arrival of migrating birds and tree blossom.
- These sources are often not very accurate because they were not intended to record climate. However they can still give us some evidence of recent climate trends.
- Between about 1550 and 1850 the UK experienced a ‘Little Ice Age’. Temperatures were sometimes low enough that the River Thames froze. The ice was thick enough for people to walk over the frozen river and even hold a fair. Great Frost of 1683–84, the worst frost recorded in England the Thames was completely frozen for two months, with the ice reaching a thickness of 28 cm in London.
How does the Natural Greenhouse Effect help us?
The Natural Greenhouse Effect was a completely natural effect before humans, and stops the Earth from being a frozen wasteland (CO2 is the most abundant greenhouse gas).
The 4 Factors contributing to the Enhanced Greenhouse Effect:
- Agriculture
- Energy
- Transport
- Industry
How does Agriculture contribute to the Enhanced Greenhouse Effect?
Trees absorb and then store Carbon Dioxide, meaning they act as storage for the most emitted greenhouse gas. However, population growth and demand for food has led to deforestation and clearing for cattle farming and rice paddies. Deforestation stops the absorption of CO2 in the atmosphere. Furthermore, these human activities produce methane which has 21 times more power than CO2. These powerful greenhouse gases enhance the greenhouse effect and cause more global warming, not to mention the 250% increase in Methane in the atmosphere since 1850.
How does Energy contribute to the Enhanced Greenhouse Effect?
Energy sources require the burning of fossil fuels to power them. The main problem with this is that CO2 is produced when you burn fossil fuels such as coal, oil, gas and wood in power stations on such a scale. The rate that these fossil fuels are being burned at is mainly down to demand of electricity. This is made worse by the increasing population and the advancement of new technologies also, which is backed up by the 30% increase of CO2 in the atmosphere since 1850. This shows how the burning of greenhouse gases and increase in CO2 affect Climate Change
How does Transport contribute to the Enhanced Greenhouse Effect?
Transport is having a negative affect on Climate Change, as most of it’s fuel involves greenhouse gas emissions. Nowadays, new models of transport are becoming available, but can be just as inefficient in terms of fuel as others. Jet aircrafts, cars, and lorries are the most common contributors, with all of these things becoming more affordable as time progresses, which isn’t helped by even more congestion on the roads, making things worse. This may be explained by the 16% increase of Nitrous Oxide in the atmosphere since 1850, explaining why this has an increasing negative impact on the climate.
How does Industry contribute to the Enhanced Greenhouse Effect?
Industrial processes are also enhancing the greenhouse effect as it produces CO2 and uses Halocarbons, which are 3,000 times more powerful than Carbon Dioxide ( taking up 1% of the atmosphere). The source of this is cements, solvents and pieces of cooling equipment, which is now in demand more than ever, with people having even more disposable income on their hands to spend on things exactly like the industry. This is all backed up by the fact that there has been an increase in the Halocarbons in the atmosphere since 1850. If this all carries on, the Industry and it’s processes will result in the climate warming even more.
What Evidence is there to suggest Human Activity is causing Climate Change? (Evidence + Why)
Evidence 1: Global average temperature
- The ten hottest years on record have occurred since 1998, with 2005, 2010 and 2014 as the hottest.
- Including 2013, 9 out of the 10 warmest years on record have occurred in the 21st century. Only one year during the 20th century – 1998, was warmer than 2013.
- Measurements of average global atmospheric temperature show a steep rise from around the 1950s to the present. Although global temperature have risen before, it is unusual for the increase to be so rapid.
Evidence 2: Arctic sea ice
- By 2012, floating sea ice in the Arctic had shrunk to less than half the amount in 1979.
- Over 90% of the world’s valley glaciers are shrinking.
- The extent of Arctic sea ice has decreased. Every year sea ice melts in spring and reaches its lowest extent in September. Warmer global temperatures have meant more ice has melted. The sharp decline in the extent of the sea ice cannot be explained by natural cycles in the Arctic.
Evidence 3: Sea level change
- The extent of Arctic sea ice has decreased. Every year sea ice melts in spring and reaches its lowest extent in September. Warmer global temperatures have meant more ice has melted. The sharp decline in the extent of the sea ice cannot be explained by natural cycles in the Arctic.
- Sea levels rose by 210mm from 1870 to 2010. They are rising because the sea expands as it warms, called thermal expansion. In future, if glaciers and ice sheets continue to melt, sea levels could rise significantly.
What is Eustatic Sea Level Rise and Thermal Expansion
Eustatic Sea Level Rise:
Warmer temperatures are causing Glaciers to shrink ond ice sheets to melt. The melting of ice on land, especially from the Greenland and Antarctic Ice sheets, means that water stored on land as ice returns to the oceans. This causes sea levels to rise.
Thermal Expansion:
Water in the oceans expands as it gets warmer - this is called thermal expansion. Scientists think this accounts for about half of the measured rise in sea levels.
Possible Consequences of Climate Change and what they could result in:
Climate Change:
Impacts Farming - Some farmers are finding crop yields to be smaller due to rising temperatures. However, in higher latitudes, some are able to grow more
Impacts Nutrition - Lower crop yields increase malnutrition, ill health and death from starvation. (Especially in lower Latitudes)
Could Mean More Deaths - Deaths due to heat are currently on the rise, while deaths due to cold have decreased
Could Lead To More Extreme Weather - Global Warming, results in Climate Change makes the weather more extreme, meaning money will be spent on predicting extreme weather and reducing the impacts and rebuilding what got damaged
Could Mean More Money Spent On Flood Defences - Low-lying coastal areas could be lost due to rising sea levels and ever increasing flooding. This could lead to migration and overcrowding in other areas
Why are projections for sea-level rise difficult to make?
They are difficult to make because:
- Prevailing winds and currents will have higher levels. Some areas of land are sinking and are densely populated, adding to the risk
- Greenland would add 7 meters to sea levels. Antarctica would add 13 meters, if their ice sheets were to melt
- Will Greenhouse gases continue to rise, or will their emissions reduce? If so, when will emissions peak (affect the rate of ice melted, and how much and e.c.t)
What are these definitions:
- Coriolis Force
- Eye
- Seasonal Distribution
- Source Area
- Track
Coriolis force – a strong force created by the earths rotation.
Eye – the centre of a tropical cyclone
Seasonal distribution – how something such as tropical cyclones occur at different times of the year.
Source area – the region in which a tropical storm first forms
Track – the path followed by a tropical storm
How do Tropical Cyclones form?
Stage 1- Warm air currents rise (number 1 in Figure 3) from the ocean. As the warm air rises, more air rushes in to replace it; then it too rises, drawn by the draught above.
Stage 2- Updraughts of air contain huge volumes of water vapour from the oceans, which condense to produce cumulonimbus clouds. Condensation releases heat energy stored in water vapour, which powers the cyclone further.
Stage 3- Coriolis force causes rising current so far to spiral around the centre of the tropical cyclone, so it resembles a whirling cylinder. It rises and cools, and some of it descends to form the clear, cloudless, still, eye of the storm.
Stage 4- As the tropical cyclone tracks away from its source, it is fed new heat and moisture from the oceans, enlarging as it does so.
Stage 5- Once it reaches a landmass, it loses its energy source from the ocean. Air pressure rises as temperature falls, winds drop, rainfall decreases, and it decays to become a mere storm.
Where do Tropical Cyclones usually form?
Tropical cyclones source areas are in the tropics, a few degrees north and south of the Equator:
- This is where the Coriolis effect adds to rotation.
- Most likely to occur in ITCZ (Intertropical Convergence Zone) - areas of permanently low pressure generated by global circulation within the Hadley Cells.
- It will be where the waters are around 26.5°C in these waters
(- Develop around June to September/October in the Northern Hemisphere
-Develop mid-January to March in the Southern Hemisphere in the Southern Hemisphere)
What are the Hazards of Tropical Cyclones?
High Winds - Tropical winds over 250km per hour at times
Intense Rainfall - The tropical cyclones take up large amounts of water from the ocean, which will result in masses of intense rain
Storm Surges - The cyclone creates big areas of low pressure, which can allo the sea level to rise, with large amounts of water being thrown up and out of bodies of water
Coastal Flooding - Intense rain and storm surges can flood the coasts, while large waves are thrown to the shore
Landslides - Landslides can occur when the ground takes up a lot of water, making it weak and unstable enough for it to break off and fall in small and large amounts.
Why is air pressure important in how strong a tropical cyclone becomes?
Air pressure is very important in how strong a tropical cyclone can become, as tropical cyclones hold a much lower air pressure than the air surrounding them (the average normal air pressure is 1013mb (millibars)). On the other hand, the ‘eye’ of the storm consists of more calm, clear and descending dense air. Overall, the higher difference or air pressure, the more powerful it will be. An example of the lowest pressures recorded are 887mb, found in Typhoon Ida in the Philippines in 1958 (winds reached up to 300km/h)
What will impact the intensity of a tropical cyclone?
The intensity of a tropical cyclone can be affected by a few things and ways (which can make it stringer or weaker depending). One reason is that warmer water will fuel the tropical cyclone more, increasing it’s intensity. A second reason is due to dissipation (losing energy), because when it reaches land, it’s fuel supply will stop. It can also lose it’s energy by running into colder waters, or if another weather system blows it the other way, or destroys it.
How do Tropical Cyclones Dissipate?
Tropical Cyclones can dissipate (lose energy) when it reaches land meaning it’s water supply is cut off, when it moves to areas of cold water meaning there is no moist air and warm water to fuel it, or when it runs into other weather systems with winds blowing the opposite way, resulting in it essentially falling apart.
What Social and Environmental Impacts do High Winds have?
Social Impacts:
- Homelessness and buildings damaged, injuries/death by flying debris
- Power Cables can get damaged.
- The winds could result in people being blown over and falling
Environmental Impacts:
- Trees uprooted and blown over
- The birds and animals living and using these uprooted trees will be affected as their habitats will be destroyed
