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Geography GCSE (OCR) > Global hazards > Flashcards

Global hazards Flashcards

1
Q

Natural Hazard

A
  • An extreme natural event or process that can lead to loss of life and/ or damage to property and severely disrupts human activity
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2
Q

What causes a tectonic hazard?

A
  • The movement of the Earth
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3
Q

What causes a Climate Hazard?

A
  • Processes in the atmosphere
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4
Q

Weather

A
  • The day to day conditions of the atmosphere involving, for example, temperature, precipitation and wind
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5
Q

Climate

A
  • The average weather conditions recorded over a period of at least 30 years
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6
Q

Atmosphere

A
  • The air above our heads
  • Mass of swirling gases, liquids and solids, such as CO2, O2, water vapour and droplets and ash
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7
Q

Circulation

A
  • Circular air movements called cells.
  • These cells all join together to form the overall circulation of the Earth’s atmosphere
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8
Q

What are the 3 circulation cells?

A
  • Hadley Cell
  • Ferrel Cell
  • Polar Cell
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9
Q

What is wind?

A
  • The movement of air from an area of high to low pressure
  • The greater the difference in pressure, the greater the winds
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10
Q

Trade winds

A
  • Winds that blow from high pressure belts to low pressure belts
  • Used by trading ships to sail
  • Mt. Washington has winds up to 372 km/hp
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11
Q

Katabatic winds

A
  • Caused by air flowing downhill
  • In Antarctica, large sloping ice sheets contribute to wind speeds of over 320 km/h
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12
Q

Jet stream

A
  • Winds that are high in the atmosphere
  • Speeds of 225 km/h recorded on Mr. Everest
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13
Q

Tropical Storms

(winds)

A
  • Very strong rotating winds
  • Start smaller but develop into strongest winds ever recorded
  • Die out when they reach land
  • Highest speed recorded was 408km/h on Barrow Island in Hurricane Olivia in 1996
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14
Q

The Albedo effect

A
  • How much a surface reflects or absorbs the Sun’s rays
  • The more reflective, the less heat it can hold
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15
Q

What happens during El Niño?

(bullet points)

A
  • Trade winds in the western Pacific Ocean weaken, stop or reverse
  • The piled up water around Australia and Indonesia moves its way back towards the eastern Pacific Ocean
  • Water in eastern Pacific Ocean gets 6-8 degrees warmer than usual
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16
Q

What happens during El Niño?

(high pressure, low pressure etc.)

A

High pressure- Australia
Low Pressure- Peru
Rainfall- South America
Drought- Australia
Flooding- Peru
Trade winds- Weaken, stop or reverse

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17
Q

What happens during a normal year?

(bullet points)

A
  • Trade winds blow westwards over Pacific Ocean, pushing warm water from Peru to Australia
  • In the eastern Pacific, off the coast of Peru, the thermocline is especially low
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18
Q

What happens during a normal year?

(high pressure, low pressure etc.)

A

High pressure- South America
Low Pressure- Australia
Rainfall- Australia
Drought- N/A
Flooding- N/A
Trade winds- East to West

19
Q

What happens during La Niña?

(bullet points)

A
  • Doesn’t always come after an El Niño year
  • Unusually cold sea surface temperature in eastern tropical Pacific
  • More extreme version of a normal year
20
Q

What happens during La Niña?

(high pressure, low pressure etc.)

A

High pressure- South America
Low Pressure- Australia
Rainfall- Australia
Drought- Peru
Flooding- Australia
Trade winds- East to West

21
Q

Thermocline

A

An abrupt temperature gradient in a body of water such as a lake or ocean, above and below the thermocline the water is at different temperatures

22
Q

Drought

A

A period of below average precipitation where the abnormally dry weather leads to a shortage of water, which can have a negative effect on vegetation, animals and people over a large area

23
Q

Arid

A
  • Lacking moisture
  • Very dry
24
Q

Causes of droughts

A

Human causes:
- Global warming
- Soil erosion
- Deforestation
- Irrigation
- Population increase
- Urbanisation

Physical causes:
- El Niño
- Climate change
- Position of ITCZ (Inter- tropical convergence zone)

25
Q

ITCZ meaning

A

Place where the Hadley cells meet

26
Q

Tropical Storm

A
  • Areas where air is rising and causing extreme low pressure on the Earth’s surface
  • This creates powerful spiralling winds that last 6-14 days with wind speeds of over 120km/h
27
Q

What are tropical storms called in the Atlantic and Pacific?

A

Hurrricanes

28
Q

What are tropical storms called in the Northwestern Pacific?

A

Typhoons

29
Q

What are tropical storms called in the Indian Ocean and the Southwestern Pacific?

A

Tropical cyclones

30
Q

Inner core

A
  • Solid metal
  • Radius of 1220km
  • Made up of iron and nickel
  • Hotter than the surface of the Sun at 6000 degrees Celsius
  • Pressure of other layers compresses inner core
31
Q

Outer core

A
  • Made up of iron and nickel
  • 2300km thick
  • 4400 degrees celsius
  • Less pressure on it so the metal that it is made up of is liquid
32
Q

Mantle

A
  • Split into lower mantle (mesosphere) and upper mantle (asthenosphere)
    -2900km thick (84% of Earth’s volume)
  • Made up of magnesium, iron, silicon and oxygen
  • Between 1000 and 3700 degrees celsius so in the upper mantle, the solid is mostly putty
33
Q

Crust

A
  • Thinnest layers of the Earth
  • Oceanic crust- Made from balsamic type rocks rich in magnesium and aluminium
  • Continental crust- Made of granite type rock, rich in silico and aluminium
34
Q

Tectonic plates

A
  • Plate tectonics is the theory that Earth’s outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core
  • The plates act like a hand and rigid shell compared to Earth’s mantle
35
Q

Plate Boundary

A
  • The line where different plates meet
  • There are 4 types of plate boundaries: Constructive, Conservative, Destructive and Collision
36
Q

Earthquake

A
  • The sudden release of energy that is the result of the movement of layers of rock in the Earth’s crust
37
Q

How do earthquakes happen?

A
  • Rough edges of plates try to move past each other and get stuck, building up energy, which is then released when the plates slip
  • Energy is released as seismic waves
38
Q

How are earthquakes measured?

(most known technique)

A

Richter Scale:
- Open- ended scale
- Measures magnitude of a tremor
- Uses seismometer
- Logarithmic scale ( so a 2 is 10x more powerful than a 1 and a 3 is 100x more powerful than a 1 etc.)

39
Q

How are earthquakes measured?

(less known technique)

A

Mercalli Scale:
- Based on what people felt/ saw during the earthquake
- Subjective scale
- Uses Roman Numerals

40
Q

Richter Scale

(Advantages)

A
  • Quantitative data
  • Objective data
  • Accurate
  • Factual
41
Q

Richter scale

(Cons)

A
  • Computer/ Seismometer could malfunction
42
Q

Mercalli Scale

(Pros)

A
  • Cheaper
  • Qualitative data
43
Q

Mercalli Scale

(Cons)

A
  • Not factual
  • People may have different opinions and experiences with earthquake based on where they were when it happened
  • Takes longer to get data
  • Subjective
44
Q

How does a tsunami form?

A

1- Eurasian plate gets dragged down/ subducted by the Pacific plate grinding under it
2- It gets pulled down so much that it springs back up when an earthquake happens
3- This causes a four-mile deep mass of water to thrust upwards
4- When the dome collapses, strong waves of around 3 feet high travel outwards at a blistering speed, creating a tsunami
5- The tsunami gets taller as it gathers more water as the waves get closer to the coast

Geography GCSE (OCR) (4 decks)

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