Global Hazards

Question 1

Define Weather

Answer 1

The day to day conditions of the atmosphere.

Question 2

Define Climate

Answer 2

The average weather recorded over at least a 30 year period.

Question 3

What are the 3 types of cells in the Tri-cellular model?

Answer 3

Polar Cells
Ferrel Cells
Hadley Cells

Question 4

Explain the Tri-cellular model

Answer 4

ITCZ: Intense heating from sun at equator creates rising air + low pressure = Hot, wet climate

• Rising air is pushed north at Equator, cooling and descending around 30 degrees and then rises, creating high pressure + clear skies = Hot, dry climate (Replicated in southern hemisphere)

Polar Cells: Cold air descends and creates high pressure. Winds blow South/North and rise, causing low pressure on opposite side (cold, dry climate in cell).

• The rising and falling of winds of high and low pressure creates Hadley and Polar cells, they don’t meet which creates the Ferrel cell

Question 5

What is High Pressure and Low Pressure?

Answer 5

High Pressure: When an air mass descends and presses down on Earth.

Low Pressure: When an air mass rises through the Earth’s atmosphere.

Question 6

Describe how circulation around a Hadley cell works

Answer 6

• At the equator, warm air rises and creates low pressure and precipitation: the ITCZ
• North/South of the Equator, cool air sinks and creates high pressure (forming a warm + dry climate)
• As warm air rises its movement is determined by winds that cause it to constantly move around the cell

Question 7

Affect of Latitude on Temperature

Answer 7

• Due to earth’s curvature some areas are affected by more concentrated solar rays (eg. Equator)
• The shorter the distance the sun’s rays pass through, the less radiation that can be reflected
• This creates higher temperatures in exposed areas like the Equator and Lower temperatures in the poles as the sun is heating a larger area due to the Earth’s axis

Question 8

Affect of Altitude on Temperature

Answer 8

• High altitude = low air pressure + colder temperatures
• -1 degree per 100m of altitude

Question 9

Affect of Winds on Temperature

Answer 9

• Surface winds move heat between different pressure belts
• Trade winds blow from high pressure to low pressure belts

Question 10

Affect of Albedo Effect on Temperature

Answer 10

• How much surfaces absorb/reflect solar rays
• Polar caps = high Albedo + cold climate
• Rainforests = low Albedo + hot climate

Question 11

Affect of Cloud Cover on Temperature

Answer 11

• Clouds reflect sun’s rays
• Thicker cloud cover reduces temperature
• Insolation is stronger the less cloud cover ( more rays reach earth’s surface)

Question 12

Affect of Ocean Currents on Temperature

Answer 12

• Ocean currents move heat across the globe
• Example: North Atlantic Drift; Cold Peruvian Current but warms UK through circulation

Question 13

Define Precipitation

Answer 13

Condensed water vapour that forms clouds and is released as either rain, sleet, hail or snow.

Question 14

What is Convectional Rainfall?

Answer 14

• Where the sun warms up ground + air
• Warm air rises as convection currents and cools at high altitudes
• Cool water vapour condenses and forms clouds

Question 15

What is Frontal Rainfall?

Answer 15

• Where warm air meets cold air: A Front
• Warm air rises over cool air + forms clouds
• Eventually form steady rainfall, common in the UK

Question 16

What is Relief Rainfall?

Answer 16

• Where winds force warm air to rise at mountains
• Cooling, condensation and precipitation on windward side
• Air descends on leeward side and forms rain shadow

Question 17

What are the wettest and driest places on Earth?

Answer 17

Wettest = Khasi Hills, Northern India
Driest = The Atacama Desert, Chile

Question 18

What is a Tropical Storm?

Answer 18

A powerful, rotating storm in the tropics : known as Cyclones, Hurricanes and Typhoons.

Question 19

What are Katabatic and Trade Winds?

Answer 19

Katabatic: Downslope winds caused by gravity causing high density air masses to fall on lower density air masses.

Trade: Winds that blow from high to low pressure belts.

Question 20

Where are Tropical storms found?

Answer 20

Hurricanes: North + Central America
Typhoons: East Asia
Cyclones: All around Indian Ocean + Eastern Australia

Question 21

Where are Droughts normally found?

Answer 21

Areas around the Tropics of Capricorn and Cancer

Question 22

What are the characteristics of Tropical Storms?

Answer 22

• Form over tropical areas
• Wind speeds of 120+ km/h
• Diameter of at least 650km
• Severe + extreme weather lasting for 6-14 days

Question 23

What is a Drought?

Answer 23

Periods when there is much less precipitation over a specific time than is usual for the area.

Question 24

What are the characteristics of Droughts?

Answer 24

• Long periods of high air pressure
• More evaporation than precipitation
• Food shortages, hunger and death
• Varied features based on location

Question 25

What are the causes of Tropical Storms?

Answer 25

**Ocean Surface Temperatures**: 26.5+ degrees, gives storms enough energy to form **Ocean Depth**: 60m+ deep to provide sufficient amount of evaporation **Coriolis Effect**: Spinning of Earth creates winds that cause spiral shape of storms **Low Air Pressure**: Low air pressure sucks in trade winds at ocean surface and absorbs moisture quick enough for the storm to grow.

Question 26

How are Tropical storms measured?

Answer 26

The Saffir-Simpson Scale

Question 27

What makes weather extreme?

Answer 27

High intensity or volume of various weather conditions that cause danger to life or civilisation.

Question 28

What are the extreme weather conditions associated with Tropical Storms?

Answer 28

• Strong Winds of 120+ km/h • **Heavy Rainfall** (leads to Flash flooding + mass movement) • Storm surges (dangerously high rise in sea level)

Question 29

What industries do Tropical Storms affect?

Answer 29

Tourism Fishing Shipping Transport

Question 30

What is El Niño?

Answer 30

When trade winds that blow from east to west are weaker, increasing the surface temperature of the ocean and causing increased rainfall in South/North America and decreased rainfall in Australia/Asia.

Question 31

What is La Niña?

Answer 31

Where the trade winds are stronger and cause decreased ocean surface temperatures: resulting in increased rainfall in Australia + Asia and weaker rainfall in North + South America.

Question 32

What effects does El Niño have on Asia?

Answer 32

• Food + water shortages • Bush fires and poor air quality • Power cuts in countries reliant on hydroelectric power (eg. Nepal)

Question 33

What are the 4 types of Plate Boundary?

Answer 33

Conservative Constructive Destructive Collision

Question 34

What is a Hot Spot?

Answer 34

A place where magma rises up through very thin oceanic crust and creates volcanic activity.

Question 35

What is a Constructive plate boundary?

Answer 35

• Where two plates are pulled apart by convection currents • Magma rises up to fill the gap • This forms a shield volcano and can cause earthquakes • The magma hardens to form crust, sometimes high enough to create volcanic islands

Question 36

What is a Conservative plate boundary?

Answer 36

• Where two plate boundaries are moving past each other • The movement creates a build up of pressure and friction • The plates lurch past each other and release the pressure as earthquakes

Question 37

What is a destructive plate boundary?

Answer 37

• Two plates are moving towards each other • Subduction of less dense oceanic crust and formation of deep ocean trench • Continental plate is crumpled to form fold mountains • Build up of friction and pressure released as earthquakes • Magma forces to surface forms composite volcano

Question 38

What is a collision plate boundary?

Answer 38

• Two continental crust plates are push together by convection currents • They collide and force each other to fold upwards and form fold mountains • The collision creates violent earthquakes

Question 39

Characteristics of Shield Volcanoes

Answer 39

• Found at constructive plate boundaries • Gentle eruptions as no trapped gases by rising magma (low pressure • Basic, runny lava that flows quickly • Gentle slope/gradient (like a shield)

Question 40

Characteristics of Composite Volcanoes

Answer 40

• Found at destructive plate boundaries • Contains trapped seawater + hot gases that build up pressure • Dangerous, explosive eruptions with viscous lava • Steep sides and composite layers of cooled ash and magma • Cooled rock can form plug at top of volcano (building up even more pressure each eruption)

Question 41

Characteristics of Shallow-focus Earthquakes

Answer 41

• Form 0-70km below Earth’s surface • Common earthquakes at all boundaries (except constructive) • 1.0-5.0 on Richter scale • Horizontally radiating seismic waves • Widespread damage

Question 42

Characteristics of Deep-Focus Earthquakes

Answer 42

• Form 70-700km below Earth’s surface • Rare earthquakes only at destructive plate boundaries (need subduction) • 6.0-8.0 on Richter Scale • Vertically radiating seismic waves • Localised damage

Question 43

How can buildings be designed to withstand Earthquakes?

Answer 43

• Deep foundations • Strong safety glass • Shock absorbers in framework • Cross bracing structure in roof to prevent collapse • Dampers in roof to reduce sway • Automatically shutting down gas pipes