1 - Hazardous Earth Flashcards
Explain Atmospheric Circulation
- Warm air rises at the ITCZ due to intense heating (low pressure)
- Air cools and falls (high pressure).
- The difference in pressure causes trade winds to bring the air back to the ITCZ
Why are trade winds curved?
Due to the Coriolanus effect the winds are curved.
Why is their intense heating?
The high angle causes the sun’s UV to be concentrated.
How are ocean currents powered?
Wind from the atmospheric circulation cells. OR due to differences in pressure.
Density and ocean currents.
At Arctic and Antarctic water water is cooled = low density, it sinks. Warmer water is pulled in. The cycle repeats.
Effect of global circulation
Transfer heat around the world.
Natural Climate Change: 2 periods
Interglacials and Glacials
How is past climate data collected?
Using ice-core data.
Causes of Natural Climate change.
Milankovich cycle (orbital), Sun radiation change, Volcanic eruptions, Asteroid Collisions, Ocean currents.
Milankovich Cycle
Every 100,000 years the orbit changes shape.
Sun radiation change.
Sunspots - more intense
More solar flares.
Volcanic eruptions
Pump ash into atmosphere blocking sunlight - cooling.
Asteroid collisions.
Debris can block sun - cooling.
Fires release CO2 - global warming.
Ocean currents and climate change.
Currents shift directing warm water elsewhere.
Human causes of Climate Change.
Industry,
Transport,
Energy Production,
Farming.
Explain Greenhouse effect.
- UV reaches atmosphere, some is reflected.
- Land and oceans absorb heat.
- Infrared is emitted, and is trapped because of greenhouse gases.
Human climate change and global temperatures
Rising,
2015: +1C from 1850
Human climate change and CO2
Rising in parallel with global temperatures.
Human climate change and ocean temperature.
Rising by 0.11C per decade (1971 - 2010)
Human climate change and arctic sea ice.
Covers 13% less each decade
Human climate change and sea levels
Risen by 14cm in 21st century.
Human climate change and extreme weather.
5x more common vs a century ago.
Consequences of Global Warming.
Coastal flooding, biodiversity loss, extreme weather, pests and disease, loss of glaciers, draughts
Tropical cyclone names
Hurricanes, cyclones, typhoons
Required water temperature for tropical cyclones
26.5C
Latitude where tropical cyclones form.
5 to 30
Tropical cyclones and pressure.
Low pressure - As warm air rises it draws in more air.
Tropical Cyclones and rotation
Coriolis effect causes a spiral rotation
Tropical cyclones and structure
- Cylinder of rising spiralling air (low pressure)
- EYE: descending high pressure air.
Tropical Cyclones and size
UP to 640km x 10km high
Tropical Cyclones and movement.
Start: Warm tropic water, move westwards.
Some: reach belt of winds blowing west and reverses direction.
Can travel 640km in a day
Saffir Simpson scale and wind speed (1->5)
Increases:
- 119-153km/h
- 252+km/h
Saffir Simpson scale and pressure.
Reduces
1: 980+ millibar
5: <920 millibar
Saffir Simpson scale and storm surge.
Increases:
1: 1 -> 1.7m
5: >5.7m
Category 5 damage
Catastophic
Category 1 damage
Some damage.
Cyclone intensifier
Water temperature
Low wind shear (different speeds/directions)
High humidity
Cyclone dissipaters
Reach land (no water to power it) Reaches colder water
Wind shear
Formation of Tropical Cyclone
- Warm sea temperatures
- High humidity
- Rapid cooling - condensing causes energy release (latent heat)
- Coriolis effect causes rotation (not enough at 5)
- Pre-existing low pressure, storms merge.
Layers of the Earth.
Lithosphere, Asthenosphere, outer core, inner core
What powers the core
Nuclear decay.
Inner core conditions
6000C
High pressure
Solid iron
Outer Core
5000C
Liquid
iron and nickel
Asphenosphere
Plastic region,
Under enough pressure that rocks flow
Lower Mantle
3000C
Lithosphere
Solid
Tectonic plates.
Convection currents and plate movement
Heat from core causes rising towards surface. The force moves plates. Falls towards core to be reheated.
Density and the lithosphere
Continental Crust : Granite (Less dense)
Oceanic Crust: Basalt (more dense)
BOTH less dense than asthenosphere.
Convergent Plate boundary
2 plates converge
denser plate subducts
Collision plate boundary.
2 plates converge
Equal density, forming fold mountains
Divergent plate boundary
Rising magma from convection currents pull apart 2 plates causing volcanic ridge.
Many earthquakes.
Conservative
2 plates slide along.
Many earthquakes
Shield volcano
Constructive boundary (divergent) OR hotspots.
Basaltic lava.
Gentle sloping sides, wide base
Frequent but effusive eruptions
Composite (strato volcano)
Andesic lava
Steep sides, narrow base
Layers from previous eruptions
Infrequent but explosive eruptions
Basaltic lava
Low viscosity - travels far
Low silica and gas content
Andesic lava
High viscosity - not as far
Less hot
High silica and gas content
Epicentre
Point on surface above focus.
Focus (hypocentre)
Central point underground
Primary impacts of Earthquakes
Death, injury
Destruction of buildings and infrastructure
Secondary impacts of earthquakes
Fires from fractured gas pipes and electricity pylons
Landslides
Disease, no sanitation
Tsunami
Primary impacts of volcanoes
Death, injury
Destruction of buildings, infrastructure and farmland
Secondary impacts of volcanoes
Atmospheric pollution (ash) Mudflows (lahars) Landslides Flooding by diverted river Tsunamis by landslide or cliff collapse.
