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Geography A Paper 1 Flashcards > Weather and Climate > Flashcards

Weather and Climate Flashcards

1
Q

Global Atmospheric Circulation

A

The Earth’s atmosphere is in constant motion, transferring heat energy around the Earth.

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2
Q

Circulation Cells

A

Different areas of the Earth receive different amounts of solar radiation: there is a surplus of heat energy at the Equator and a deficit at the Poles. Three circulation cells in each hemisphere redistribute this heat energy.

  1. At the Equator, warmed air rises to 15 km, causing low pressure. The air current divides, cools and moves north and south to form Hadley cells. The cooled air sinks at 30º north and south of the Equator, leading to high pressure.
  2. Some of the cooled air moves back towards the Equator as trade winds. The rest travels towards the Poles, forming the lower part of Ferrel cells.
  3. At 60º north and south, the warmer air of the Ferrel cells meets colder polar air. The warmer air rises to form Polar cells. This air travels to the Poles, where it cools and sinks, forming areas of high pressure.
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3
Q

Oceanic Circulation

A

Ocean currents also transfer heat energy from areas of surplus (Equator) to areas of deficit (Poles). Wind-driven surface currents and deeper ocean currents move warm water towards the Poles and colder water towards the Equator.
In the Arctic and Antarctic, water gets very cold and dense, so it sinks. Warmer water from the Equator replaces this surface water, creating ocean currents, such as the Gulf Stream. Cooled water flows back towards the Equator, forming cold currents, such as the Humboldt Current.

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4
Q

Natural Climate Change

A

The average climatic conditions of the Earth change naturally over time, creatin both warmer and colder periods.

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5
Q

The Quaternary Period

A

The Quaternary period covers the last 2.6 million years when there have been:
- more than 60 cold periods with ice advances, lasting about 100 000 years
- warmer interglacial periods lasting about 15 000 years.

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6
Q

Recent Temperature Changes

A

In the last 250 years, the Earth’s temperature has risen significantly compared to before. Average temperature in the middle of the last Ice Age was about 5ºC below today’s average temperature.

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7
Q

Milankovitch Cycles

A

These are long-term changes to the Earth’s orbit and position, changing how much solar radiation the Earth receives - resulting in changes in climate. These include eccentricity, axial tilt and precession.

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8
Q

Eccentricity Cycle

A

The Earth’s orbit changes approximately every 100 000 years. More circular orbit –> cooler periods; more elliptical orbit –> warmer periods.

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9
Q

Axial Tilt Cycle

A

Roughly every 40 000 years, the tilt of the Earth’s axis varies. Greater angle of tilt –> hotter summer and colder winter.

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10
Q

Precession Cycle

A

The Earth ‘wobbles’ on its axis roughly every 24 000 years, changing the direction the axis is facing. This can affect the differences between seasons.

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11
Q

Other natural causes of climate change

A

Solar radiation levels vary.
Lower solar radiation makes glacial periods more likely; higher solar radiation leads to interglacial periods.

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12
Q

Evidence of climate change

A
  • Historical sources, such as diaries
  • Ice cores trap volcanic ash, microbes, air bubbles. These reveal information on climate when the ice formed.
  • Preserved pollen provides evidence on warm and cold growing conditions.
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13
Q

Human Activity

A

A key contributor to global warming is rising levels of greenhouse gases, which are released by human activities including industry, transport, energy production and farming.

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14
Q

Enhanced Greenhouse Effect

A

Human activity releases increasing levels of CO2 and other greenhouse gases into the atmosphere, increasing the greenhouse effect - more warming.

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15
Q

Human Causes of climate change

A
  • Industry - rising demand for consumer goods increases production, burning more fossil fuels, which release greenhouse gases.
  • Farming - global population growth increases demand for food. Mechanisation burns more fuel, and the demand for meat for Western-style diets increases methane levels.
  • Transport - rising affluence increases car ownership and air travel, releasing more greenhouse gases into the atmosphere.
  • Energy - new technologies and population growth increase demand for electricity produced from coal, oil and natural gas, which all produce greenhouse gases.
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16
Q

Negative impacts of climate change on the environment

A
  • Melting ice sheets and retreating glaciers add water to oceans, making sea levels rise. Arctic melting could cause the Gulf Stream to move further south, leading to colder temperatures in Western Europe.
  • Rising sea levels will cause coastal flooding. Soils will become contaminated with salt, causing plants to die.
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17
Q

Negative impacts of climate change on people

A
  • Changes in climates near the Equator, such as Africa’s Sahel, could mean longer periods of less rainfall, so lower crop yields.
  • Many low-lying island like the Maldives face greater flood risk from rising sea levels. There will be more coastal flooding, loss of beaches and loss of coral reefs. Some islands will have to be evacuated.
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18
Q

The UK’s Climate

A

The UK has a distinct climate, which has changed over the last 1000 years and which varies from region to region.

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19
Q

Past Climate Changes

A
  • During the Medieval Warm Period (950-1100) higher temperatures meant greater crop yields and a growing population. This was due to increased solar radiation.
  • During the Little Ice Age (1600-1685) temperatures were low enough to freeze the Thames, due to increased volcanic activity and decreased solar radiation.
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20
Q

The UK’s Climate Today

A

Today, the UK has a temperate, wet climate. Extreme weather is rare, but the meeting of major air masses make frontal rainfall common.

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21
Q

Impact of the UK’s Location

A

The UK is located between 50º N and 60º N. This and other factors have an impact on climate.
1. Maritime influence: most of the air reaching the UK contains lots of moisture, as we are surrounded by sea, leading to rainfall all year.
2. Prevailing wind: the main or prevailing wind for the UK comes from the south-west. This air travels long distances over the Atlantic Ocean, bringing moisture, leading to more rainfall.
3. North Atlantic Drift: this ocean current brings warm water north to the UK. In the winter, this makes the UK climate milder than would be expected for its latitude.
4. Atmospheric circulation: the UK is near the ‘boundary’ between the northern Ferrel and Polar circulation cells. This is where warmer air from the south and cooler air from the north meet, causing unsettled weather.
5. Altitude: the higher an area is, the cooler and wetter it is, so areas in the UK vary.

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22
Q

Tropic Cyclones

A

Tropical cyclones are also known as hurricanes and typhoons. You need to know how, where and when they occur, and their key characteristics.

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23
Q

How Tropical Cyclones Form

A

Tropical cyclones need a source of warm, moist air and warm ocean temperatures (27ºC plus).
1. Rising warm air causes thunderstorms, which group together, making a strong flow.
2. An area of very low pressure forms at the centre of the converged storms.
3. The storms rotate, accelerating in and up, forming a tropical cyclone.

Tropical cyclones form in tropical areas where a rotation force, created by the Coriolis effect, forms part of the global circulation of the atmosphere. The rotation is due to deflection of winds moving north and south of the Equator.

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24
Q

Tropical Cyclone Characteristics

A
  • Very low pressure
  • Form a cylinder of rising, spiralling air surrounding an eye of descending, high-pressure air
  • Cloud banks called the eye wall surround the eye
  • Often 400 km wide and 10 km high
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25
Q

Frequency of Tropical Cyclones

A

Tropical cyclones are more likely to happen:
- June-November in the northern tropics
- November-April in the southern tropics
They are more likely to happen in cooler years, but numbers are hard to predict.

26
Q

Tropical Cyclone Movement

A
  • Cyclone movement is determined by the prevailing winds and ocean currents
  • The cyclone’s track is influenced by how far it travels over the ocean: it will collect more moisture, increasing its strength
  • Tropical cyclones can travel 600 km a day at 40 km/h
  • Cyclone movement can be forecast using satellite images
27
Q

Tropical Cyclone Hazards

A

Tropical cyclones are natural weather hazards in themselves, and also because of the hazardous effects they produce.

28
Q

Hazards associated with tropical cyclones

A
  • Storm surges - tropical cyclones can cause a large mass of water to hit land, causing damage to beaches and coastal habitats.
  • Landslides - intense rainfall causes the soil to be saturated and become heavy. This saturated soil then slides downhill.
  • Coastal flooding - damage to property and lives is increased due to flooding.
  • Intense rainfall - heavy persistent rainfall can lead to flooding, damaging property and leaving people stranded.
  • High winds - winds as high as 240 km/h can uproot trees and buildings, potentially causing injuries and loss of life.
29
Q

Hurricane Sandy

A

You will need to know and understand the different social, economic and environmental impacts that tropical cyclones can have on a named developed country.

30
Q

Key facts: Hurricane Sandy

A
  1. The hurricane travelled across the Caribbean Sea, affecting the island nations of Jamaica, Cuba and Haiti, before moving north to reach the USA.
  2. It reached New Jersey on 29 October 2012.
  3. By the time the hurricane reached land, wind speeds of 129 km/h were recorded.
  4. The storm surges caused most of the damage to East Coast states.
  5. The use of social media such as Twitter and photographs uploaded to Flickr helped with damage assessment.
31
Q

What was the impact of Hurricane Sandy?

A

Social
- Death toll of at least 150 people
- Many areas left without electricity
- Homes and businesses damaged
- Schools closed for days

Economic
- Estimated property damage: US$65 billion
- Government had to pay for petrol to be brought in as supplies ran out
- Income from tourism affected by cancellation of New York Marathon

Environmental
- Storm surge caused significant damage to coastal nature reserves like the Prime Hook National Wildlife Refuge in Delaware
- Raw sewage leaked into the waters around New York and New Jersey, damaging habitats

32
Q

What was the response to Hurricane Sandy?

A
  • Individuals: The concert for Sandy Relief with artists such as Bon Jovi.
  • Organisations: The American Red Cross helped by providing relief to victims.
  • Government: Billions of dollars were voted through legislation to help with rebuilding and supporting victims. New York set up a new local government office to support the rebuilding.
33
Q

For a tropical cyclone you have studied in a named developed country, explain two environmental impacts. (4 marks)

A

One of the environmental impacts of Hurricane Sandy was pollution of water sources. The storm surges from the hurricane caused large-scale flooding, which resulted in raw sewage leaking into nearby water sources and damaging habitats. Another environmental impact was the damage to coastal nature reserves. For example, the storm surge caused damage to the Prime Hook National Wildlife Refuge in the state of Delaware.

34
Q

Typhoon Haiyan

A

You will need to know and understand the different social, economic and environmental impacts that tropical cyclones can have on a named emerging or developing country.

35
Q

Key facts: Typhoon Haiyan

A
  1. Formed on 2 November 2013 in the South Pacific Ocean, close to the Federated States of Micronesia.
  2. When the typhoon reached land, wind speeds of over 300 km/h were recorded.
  3. Most of the damage caused by the typhoon was on the islands of Samar and Leyte.
  4. Flooding and landslides were reported across the Philippines.
36
Q

What was the impact of Typhoon Haiyan?

A

Social
- An estimated 6 000 people killed and many more missing
- Significant loss of power
- An estimated 600 000 people displaced from their homes
- Many homes left destroyed

Economic
- Estimated damage: US$2 billion
- Damage and disruption to infrastructure blocked transport across islands, making provision of aid and support difficult and expensive

Environmental
- Mangroves damaged across the islands
- Trees uprooted
- Oil spills from a tanker caused sea pollution

37
Q

What was the response to Typhoon Haiyan?

A
  • Individuals: people in countries such as the UK and Canada gave money towards the relief efforts.
  • Organisations: the World Health Organisation coordinated the international response to help the Philippine government meet the acute need for healthcare services.
  • Governments: in order to direct funds to help support the aftermath, the Philippines were put in a ‘state of national calamity’. Aid in the form of loans and grants was provided by countries like the UK, which gave a £10 million package including emergency shelter, water and household items.
38
Q

For a tropical cyclone you have studied in a named emerging or developing country, explain two social impacts.

A

One of the social impacts of Typhoon Haiyan was the high death toll, with over 6 000 people estimated killed and many more thousands missing. A second social impact was the destruction of homes, with many people left homeless.

39
Q

Drought causes and locations

A

Drought is caused by a number of complex factors. Some places are more vulnerable to drought than others.

40
Q

Arid or Drought?

A

In arid areas, the normal climate is dry, because they normally have high pressure, leading to low precipitation.

The key factors in whether an area is likely to suffer from drought are:
- how it gets precipitation - at any time or in a rainy season
- when precipitation occurs - during winter when soil can absorb rain more easily, or in summer.

41
Q

Arid environments

A
  • Permanent low precipitations. The Sahara is arid; the Kalahari is semi-arid
  • 10-250 mm precipitation a year
  • High pressure conditions, no cloud cover
  • Mostly located in the tropics (between 23.5ºN and 23.5ºS of the Equator)
42
Q

Drought conditions

A
  • Temporary low precipitation conditions
  • In the UK, drought is 15 consecutive days without rainfall
  • High pressure conditions, no cloud cover
  • Located anywhere globally
43
Q

Natural causes of drought

A
  • Meteorological - this is where an area receives less than average precipitation. In the UK, high pressure (blocking anticyclone) forces away the low pressure systems that bring rain around it. This means no rain falls over all or part of the UK for weeks.
  • Hydrological - This is where the hydrological cycle receives less rainfall than normal. Less precipitation means groundwater supplies and reservoirs are not refilled, leading to drought conditions.
44
Q

Global circulation and drought

A

Global circulation makes some locations more vulnerable to drought. Where the Hadley and Ferrel circulation cells are, such as Africa’s Sahel, descending dry air means there is little precipitation. Rainfall occurs during a wet season; if the rains do not come, the area has drought conditions.

45
Q

California, USA

A

You need to know the impacts of drought on people and ecosystems - and how individuals, organisations and governments responded - in a named developed country.

46
Q

California drought, 2012 to present

A

In January 2014, California was experiencing its third year of drought and a state of emergency was declared. Lower than normal rainfall and snowfall on the west coast, and dependence on the over-used Colorado River, had caused water supplies to drop.

47
Q

Main hazards

A

The main hazards in this drought were:
- Subsidence as groundwater levels dropped, causing land to settle at a lower level
- Contamination of land and drinking water by seawater, drawn inland by a lack of pressure
- Wildfires which started and spread quickly, as vegetation was so dry.

48
Q

What are the impacts on people in California?

A
  • Costing California US$2.7 billion a year - less state money to spend on services for people
  • Increased extraction from groundwater/aquifer causing subsidence - infrastructure and buildings damaged e.g. in the San Joaquin Valley
  • 542 000 acres taken out of crop production - loss of food and income
  • Risk to people’s lives and property
49
Q

What are the impacts on ecosystems in California?

A
  • Central Valley is worst affected area
  • Warm and windy weather led to wildfires - environmental damage, air pollution, destroys wildlife and habitats
  • Water diverted, so wetlands and rivers get less - impacts on natural environment and wildlife, e.g. rivers too low for salmon to breed in
50
Q

How have Californians responded?

A

Government
- Ran public education campaigns, such as Save our Water
- Brought in state laws requiring a 25% cut in water use in California

Organisations
- University of California research project for effectively managing groundwater

Individuals
- Farmers encouraged to use water-efficient irrigation, such as drip irrigation
- Homeowners encouraged to check for water leaks
- Protestors campaigned against companies selling bottled local water

51
Q

Ethiopia

A

You need to know the impacts of drought on people and ecosystems - and how individuals, organisations and governments responded - in a named emerging or developing country.

52
Q

Ethiopia, 2015

A

Ethiopia has suffered multiple droughts since the 1980s, when the short rainy seasons began to get shorter, and the long rainy seasons got later and less predictable. 85% of the people of Ethiopia live in rural areas and rely on agriculture, so low rainfall can be devastating. The 2015 drought was the worst in 30 years.

53
Q

Main Hazards

A

The main hazards in this drought were:
- reduction in crop yields leading to malnutrition and death for people and livestock
- longer journeys to find water, taking children out of school and farmers out of fields
- migration in search for ways to survive, breaking up communities

54
Q

Impact of Ethiopian drought on people

A
  • Death of livestock causes a food crisis
  • Loss of crops means maize price rockets
  • People eat less, become weak from malnutrition and more vulnerable to disease
  • Girls have to walk further to get water, so cannot go to school
  • Long grasses used for roofing cannot group, so homes are unprotected
55
Q

Impact of Ethiopian drought on ecosystems

A
  • Loss of habitat for fish and wildlife due to low water levels in reservoirs, lakes and ponds
  • Increase in disease in wild animals, because of reduced food and water supplies
  • Migration of wildlife
  • Loss of 200 000 hectares of forest every year due to forest fires
  • Extinction of some species, e.g. Grevy zebras
  • Wind and water erosion of soil
56
Q

What has the response been?

A

Governments
- Overseas governments have given aid, e.g. the USA gave US$128.4 million in food aid for Ethiopians in 2015.

Organisations
- Aid agencies such as Oxfam and UNICEF are helping people to get water supplies.
- Education charities are trying to help people get jobs in urban areas.

Individuals
- Large charity events like Live Aid have helped raise awareness and money.

57
Q

The World’s Ecosystems

A

Large-scale ecosystems are found in different parts of the world and have different characteristics. Climate and local factors each play a part in where ecosystems occur.

58
Q

Climate

A

The Earth’s climate depends on energy from the Sun. It affects growing conditions for vegetation, and affects the location and characteristics of large-scale ecosystems.

59
Q

Temperature

A

Temperatures are lower at higher latitudes, so boreal forests are much colder than tropical rainforests. Growing seasons are longer in warmer locations.

60
Q

Precipitation

A

The global circulation system influences precipitation. Desert areas have low precipitation due to descending dry air.

61
Q

Sunshine Hours

A

Lower sunshine hours in tundra ecosystems mean much less sunlight for plants to carry out photosynthesis than in tropical rainforests.

62
Q

Local Factors

A

Two local factors affect the distribution of large-scale ecosystems.
1. Rock and soil type differences can lead to different vegetation in the same ecosystem. In NW Australia, poor, sandy soil means grasses are shorter than in other areas of tropical grassland.
2. Altitude differences can lead to different plants growing within the same ecosystem. The higher the altitude, the lower the temperature. At low altitudes, lowland rainforests and mangroves grow; at cloud level (1 200 m), moist cloud forests occur.

Geography A Paper 1 Flashcards (4 decks)

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