Geography GCSE Eduqas Theme 5

What are glacial periods?

Cold periods in Earth’s history

What are interglacial periods?

Warmer periods in Earth’s history

What are three reasons why the climate has changed naturally?

• Milankovitch cycles (changes in the Earth’s tilt and orbit)

• Volcanic eruptions

• Changes in the output of solar radiation

What is weather defined as?

The atmospheric conditions at a particular place and time; includes temperature, precipitation, wind and sunshine

What is climate defined as?

The average weather over a long period (at least 30 years) of time

What is climate change defined as?

A large-scale long-term shift in the Earth’s weather patterns, especially average temperatures

What is carbon dioxide defined as?

A colourless and odourless gas, made of carbon and oxygen, found in the atmosphereHaW

What is glaciation defined as?

The process by which land is covered by glaciers

What is the Milankovitch theory

• Natural wobble of the earth and its change in tilt and orbit affects the amount of solar energy that the Earths receives

• These changes mean that the Earth’s orbit is not a perfect circle so it’s sometimes closer to the sun and sometimes further away which influences long-term climate

What is solar output defined as?

The amount of energy given off by the sun

How is solar output often determined?

By the number of sunspots

What are aerosols defined as?

Tiny particles of dust volcanic gas in the atmosphere that can reflect the sun’s energy back into space

What are fossil fuels defined as?

Stores of carbon made from the remains of living organisms. Coal, oil and gas

How do volcanic eruptions make the climate cooler?

• Eject ash and sulphur dioxide into the lower stratosphere

• The jet stream can take the volcanic material around the globe

• The mixture of sulphur dioxide and ash forms an aerosol

• These reflect the sun’s energy back into space which reduces the amount of solar energy reaching the Earth’s surface

• This, therefore, reduces the temperature of the Earth

• This period of cooling after a volcanic eruption is called a global dimming / volcanic winter

What are some different sources of evidence for climate change?

• Fossils of plants and animals found in places where they could not live today

• Ice cores from the Antarctic show that amounts of carbon dioxide and methane in the atmosphere have change over the past 420,000 years

• Glaciation in places now free of ice

• Studies of tree rings show that growing seasons have varied in length in the past

• Pollen analysis from sediment cores

• Historical records such as diary extracts, records of crop yields and paintings

How do tree rings work as evidence for climate change?

• Fossilised tree remains enabled scientists to examine the climate over of thousands of years

• Each year, a new tree ring is formed

• During good growing conditions, such as warmer and wetter years, trees grow more and so the rings are thicker

• If the rings are narrow and close together, there is less growth, indicating a cooler period

What are the limitations of tree rings and historical records compared to ice cores?

• Historical evidence is not as strong because written accounts and paintings can be bias

• Tree growth can be affected by things other than climate

• Neither tree rings or historical evidence can cover as large a time period as ice cores so patterns cannot be proven

How do ice cores provide evidence for past climate?

• A sample of ice is obtained by drilling into the ice

• The deeper the drill goes down, the older the ice

• The snowfall from each winter is covered over by the following years of winter snowfall

• Each layer contains trapped gases from the atmosphere through snow fell through

• The layers gradually turn into ice

• Gas trapped in this ice can be analysed to tell us about the atmosphere of the past

• Scientists can reveal a record of the climate from the last 650,000 years

What are some recent evidence for climate change?

• Increasing levels of CO₂ in the atmosphere. Scientists have been acc in the atmosphere. Scientists have been accurately measuring CO₂ levels in the atmosphere since 1958

• Shifting seasons leading to changes in the migrations patterns of birds and insects

• Glaciers and ice sheets melting and retreating

• Measurements by the Met Global Office show that average global temperature have increased by 0.6°C

What are all living things made of?

Carbon

What is the carbon cycle?

A series of stores and flows that lock carbon and move in between living things, land, sea, and our human atmosphere

What is the definition of carbon flows?

The movement of carbon between stores in the carbon cycle

Where is carbon stored in the short term and long term

In the short term, carbon in kept or stored in the atmosphere, oceans, and biosphere; in the long term, carbon is stored in fossil fuels

What is the definition of photosynthesis?

The process in which green plants absorb light energy from the sun using chlorophyll in their leaves to transform water and CO₂ into a sugar called glucose

What is the greenhouse effect?

The natural process that results in the warming up of the Earth's atmosphere. Without it life would not be possible on Earth

What is the enhanced greenhouse effect?

The process where increasingly large volumes of greenhouse gases in the atmosphere (such as CO₂) absorb even more of the escaping long wave energy and cause our atmosphere to warm up. This heat is re-radiated back to the planet causing global warning

What human activities cause the enhanced greenhouse effect and affect the carbon cycle?

• Burning fossil fuels, for example coal, gas and oil releasing CO₂

• Deforestation: trees absorb CO₂ during photosynthesis

• Dumping waste in landfill: when waste decomposes it produces methane, which is a greenhouse gas

• Farming causes the release of methane, for example as part of the digestive process in cattle

What is global warning?

The pattern of increasing global temperatures

What is sulphur dioxide (SO₂)?

A chemical compound of sulphur and oxygen, a toxic gas with a pungent smell

What is the stratosphere?

The second major layer of the Earth’s atmosphere, above the troposphere

What is an example of a volcano that causes global cooling?

Mount Pinatubo

• On 15th June 1991, Mount Pinatubo in the Philippines erupted

• 10km³ of ash was ejected, blocking solar radiation

• 15 million tonnes of SO₂ went into the stratosphere and formed a layer of sulphuric acid droplets which absorbed and scattered solar radiation

• Mean world temperatures deceased by 0.5°C

What is a tropical storm?

A severe low-pressure weather system which develops over tropical maritime areas

What is a drought?

A lack of precipitation in an area for a long period of time leasing to a shortage of water

What is insolation?

Solar radiation that reaches the Earth’s surface (energy received per cm²)

How is low pressure caused?

Rising air leads to low pressure at the Earth’s surface

How is high pressure caused?

Descending air leads to high pressure at the Earth’s surface

What is the tropopause?

The boundary separating the troposphere, where all weather takes place, from the stratosphere

What is the Intertropical convergence zone (ITCZ)

A zone of convergence at the equator where the trade winds meet

What is the definition for global atmospheric circulation?

Worldwide system of winds which are driven by the heat at the Equator

What is a weather hazard?

An extreme weather event that threatens people and property

What are tropical storms known as in different parts of the world?

• Hurricanes

• Typhoons

• Cyclones

When and where do tropical storms form?

• They form over tropical seas between 5° and 30° north and south of the Equator, never on it, and quickly lose strength over land as they travel further north or south over cooler waters

• They form when sea temperatures are above 27°C

What are characteristics of a tropical storm?

• They move westward

• Can travel 600km a day with wind speeds reaching over 120kph

• They give heavy rainfall which can cause severe flooding, and they die out when they reach land

• High winds and low pressure generate large waves and storm surges which can cause flooding in coastal areas

What is a storm surge?

A secondary effect caused by many tropical storms. They cause sea levels to rise due to the strong winds of tropical storms pushing water into the shore and low pressure causing a bulge of water to rise in the storm centre

When do tropical storms form in the northern hemisphere?

In the northern hemisphere, most tropical storms occur between June and November, when the ITCZ is overhead, with a peak in September

When do tropical storms form in the southern hemisphere?

In the southern hemisphere, the season lasts from November to April, then the hemisphere tilts towards the sun and the ITCZ migrates south of the equator

As tropical storms are powered by warming oceans, global warming is likely to mean these storms will…

1. Become more powerful (warmer temperatures = more evaporation)

2. Become more frequent (oceans will be over 26°C for longer so storms season will be longer)

3. Occur in more places (larger areas of ocean will be over 26°C)

What is prevailing wind?

The direction from which wind most frequently blows in a particular place

What is a monsoon climate characterised by?

A seasonal change in the direction of the prevailing winds which leads to distinct wet and dry seasons

How is the South Asia monsoon caused?

1. The ground is strongly heated by solar energy

2. The air rises creating a zone of low pressure

3. Moist air from above the Indian Ocean is drawn in to the area of low pressure to fill the gap

4. The moisture condenses forming towering rain clouds

What is a heatwave?

An extended period of hot weather when temperatures are at least 4.5°C above average for two or more days

What type of weather is a heatwave associated with?

High pressure which has become stationary over an area

What statistics does Met office research show in Europe about heatwaves?

In Europe, heatwaves are now ten times more likely than they were before the year 2000

What is a drought?

A lack of precipitation in an area for a long period of time, often several months or even years, leading to a shortage of water

Droughts can happen anywhere but where are the most severe droughts located in during recent decades?

• Australia

• South America - Brazil

• Africa - the Sahel (south of the Sahara Desert)

• Asia - areas of China and India

• The mediterranean

Droughts affect areas where there is:

1. Little rainfall

2. A shortage of water stored in rivers, lakes, and aquifers

3. Human impacts such as deforestation and intensive agriculture (e.g. Sub Sahara Africa, but also more developed areas such as California and Australia)

Why are heatwaves often linked with droughts?

Because the high pressure systems that cause them produce extended periods of clear skies which raise temperatures as well as reducing rainfall

When do high pressure weather hazards occur?

When air in the atmosphere is descending and pressing down on the Earth

What does high pressure lead to?

Light winds and dry weather conditions

What happens when high pressure lasts for a long period of time?

It can cause weather hazards such as heatwaves and drought

Droughts develop slowly, over a large area, with a beginning and end often difficult to identify. They are a result of:

• A lack of rainfall

• An environment ,soil or bedrock which is poor at storing and retaining water

• Hot weather which increases evaporation of water

What is an aquifer?

An underground layer of permeable rock containing water that can be extracted using a well/pump

What is a snowpack?

Layers of snow that accumulate in high altitudes. Their slow melting feeds streams and rivers

What is the jet stream?

A narrow zone of high-speed winds, typically around 30,000 feet high in the atmosphere, which drives global weather patterns

What is the jet stream caused by?

Temperature differences in the atmosphere.

How does global warming slow down the jet stream?

As is reduces the temperature differences

What is precipitation?

Any form of water falling from the sky

What is temperate maritime climate characterised by?

The absence of extreme climactic conditions, with mild winter temperatures and warm summers; rainfall is frequent but not extreme

Where is temperate maritime climate found?

Between 23.5° and 66.5° of latitude

What is the North Atlantic Drift (also known as the Gulf Stream)?

An ocean current which stretches from the Gulf of Mexico to north-western Europe

What are air masses?

Large volumes of air with the same temperature and humidity throughout

What climate does the UK have?

Temperate maritime climate that is heavily influenced by latitude and the sea

What is the prevailing wind direction in the UK?

From the south-west, this brings moisture from the Atlantic Ocean and frequent rainfall

What are the factors affecting climate?

• Latitude

• Altitude

• Ocean currents

• Distance from the sea (continentality)

Why does Latitude affect climate?

Places nearer the equator are much warmer than places near the pole this explains why the North has cooler temperatures than the South

Why does Altitude affect climate?

Mountain areas have colder temperatures, temperatures decrease by 1°C for every 100m of elevation

Why do Ocean currents affect climate?

The North Atlantic Drift brings warmer water to the UK’s shores and keeps the climate mild in winter and cool in summer

Why does Distance from the sea (continentality) affect climate?

In the UK, places near the sea have maritime climates (where the sea cools summer temperatures and warms winter temperatures as the sea is less dense than the land and takes longer to heat up and cooldown). Places inland have continental climates (surrounded by land that heats up quickly in the summer and cools down quickly in the winter). Being an island, most of the UK experiences a maritime climate

What wind direction does each different air mass that is brought to the UK come from and what effect does it have on the weather?

• North-westerly brings polar maritime air: cool and showery

• South-westerly brings tropical maritime air: mild and wet

• South-easterly brings tropical continental air: hot and dry

• Easterly brings polar continental air: hot in summer and cold in winter

• Northerly bring Arctic air: cold with snow in winter

What type of climate does the west of the UK experience more than the east?

The west of the UK experiences a more maritime climate than the east, particularly the winter months

What type weather is associated with low-pressure?

• Low-pressure systems, or depressions, produce cloudy, rainy and windy weather, and often affect the UK, particularly in the winter months

• Depressions begin in the Atlantic, moving eastwards across the UK

• They bring frontal rainfall (as warm tropical maritime air mass is forced to rise up and over old polar maritime air mass)

• Within the low pressure there are usually fronts where one air mass rises above another

• As air rises and cools, water vapor condenses to form clouds and precipitation

What type weather is associated with high-pressure?

• High-pressure areas or anticyclones give low wind speeds and stable conditions with little clouds or rain

• In summer, anticyclones usually bring dry and hot weather, which may lead to drought. Rapidly rising warm air may result in convectional rainfall and thunderstorms

• In winter they bring clear skies and therefore cold nights and perhaps some ice and fog

What is a front?

The boundary where two air masses meet

Explain convectional rainfall

• When the land warms up it heats the air above it, causing the air to expand and rise

• As the air rises it cools and condenses, and large cumulonimbus clouds are formed, leading to heavy rainfall

• This type of rainfall is common in tropical areas

What is a microclimate?

The climate of a small-scale area

What are examples of microclimates?

• Woodland

• Lake

• Uplands

• Coasts

• Urban areas

How does an urban microclimate happen?

• Urban heat islands: The result of the release and reflection of heat from buildings and the absorption by concrete, brick and tarmac of heat during the day, and its release at night

• Urban precipitation: In the summer months, the extra heat generated may cause air to rise, which leads to convectional rainstorms

• Urban winds: Urban areas are less windy than surroundings rural areas as buildings act as a barrier to the flow of air

How do lakes create a microclimate?

The water cools down places around the water

How do trees create a microclimate?

They provide shade, reducing temperatures underneath them, and act as a barrier to wind on their leeward side

How does the nutrient cycle work?

• Weathered rock releases nutrients into the soil

• Water is added to the soil by rainfall

• Plants absorb the nutrients through their roots and leaves