GEG 133

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  • Created by: lilley
  • Created on: 13-01-20 11:56
What is a tornado?
Tall rotating column of air in contact with ground and cumulonimbus cloud. Consists of moisture from the pressure gradient resulting in condensation.
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How many occur in USA, UK and Bangladesh?
USA 900, Bangladesh 250 and UK 34.
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In the USA what is the comparison between tornado events to hurricanes?
10 hurricanes, 1418 tornadoes.
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How can tornadoes be measured for their intensity levels?
Enhanced Fujita Intensity Scale.
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What are the comparisons between Bangladesh tornadoes vs cyclones?
Less common that USA, 250 reported 1865-2014, pre and post monsoon, 9667 fatalities.
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How many children die in pods and ditches in Bangladesh?
>5 years; ponds 43% and ditches are 26%.
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What are rip currents?
Seaward flows that extend beyond the surf zone, driven by breaking waves.
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What are the different alongshore variations?
Bathymetric, channel, focussed, boundary, hydrodynamic and hybrid types.
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What is a heatwave?
A period where temperature measurements are high relative to typical seasonal conditions for a given location. They mean different things in different locations.
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What is an anticyclone?
Large-scale high pressure system, light winds, descending air inhibits cloud formation. increased incoming solar radiation in summer/day and increased outgoing radiation in winter/night.
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When temperatures are cool what processes are more effective?
Radiation, conduction, convection and perspiration.
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When temperatures are warm what processes are more effective
Only perspiration with increased water intake.
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What are other factors in heat stress apart from temperature?
Humidity, humans adjust to temperatures greater than their body temperature through perspiration.
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What is a wet bulb temperature?
Measures a lower temperature because the air around it uses energy to evaporate water. Once the air can evaporate no more it has reached the wet bulb temperature Tw.
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What wet bulb temperature can't humans survive?
Tw 35C.
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Why are anticyclones being associated with poor air quality?
Temperature inversions and clear skies and hence strong radiation enhance ozone production.
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What areas experience drought characteristics?
Subtropical regions experience dry, clear high-pressure systems for much of the year with wet seasons.
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What can rainfall variability in these regions lead to?
Meteorological drought: periods of lower rainfall.
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What are the causes of decadal rainfall variability - regional forcing?
Dry ground reduces evaporation and precipitation, land use changes alter albedo and positive feedbacks.
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What are the causes of decadal rainfall variability - remote forcing?
Global and decadal scale variability in the coupled atmosphere ocean system. E.g drought in Australia often associated with El Nino phase of ENSO.
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What is El Nino?
Warm surface waters off the coast of Peru lead to reduced fish harvests.
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What is the Southern Oscillation?
Normal; high pressure in central pacific, low pressure to the West.
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What is the ENSO process?
1. Trade winds push water west --> cold water upwelling in at the equator in the east --> western waters warmer than eastern waters. 2. Trade winds collapse --> cold up-welling at equator weakens.
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How do wildfires occur?
Ignited by; lightening, rockfall sparks, volcanic eruptions and human activity.
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How often to wildfires occur?
3-4 million km2 burn annually worldwide, 3% of global vegetated land surface.
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How much are humans responsible for wildfires?
Humans burn around 1 million km2 of forest and grassland around the world.
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What are the types of forest fires?
Surface and Crown.
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What changes the fire fronts speed and shape?
Travelling uphill and direction of wind.
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What is residence time?
The length of time that the fire burns for.
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What is the difference between intensity and severity?
Intensity: physical energy of the fire. Severity: damage the fire does.
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What are post-fire impacts?
Flooding and erosion, soil water repellence.
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What are positive ecological impacts of wildfires?
Removal of old vegetation, triggers seed germination, increases species diveristy and is carbon neutral.
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What is a slope failure?
The downward movement under gravity of soil/rock (landslide) or snow/ice (snow avalanche).
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What are the components of slope failures?
Source/head/scar, body/cute and toe/fan.
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What is the driving force of slope stability?
Shear stress, gravity, weight and slope angle.
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What is the resistance of slope materials?
Shear strength, cohesion, cement and friction.
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What is the Mohr-Coulomb failure criterion?
Slope failure occurs on a critically oriented plane when gravitational shear stress on the plane exceeds the shear strength given by tf=c + o tan.
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What are the factors contributing to slope failure?
Steep slopes, loading, weak materials, weathering, water and trigger.
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What is the correlation between landslides and earthquakes?
Number and extent correlate with magnitude. Distances correlate with focal depth.
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What are the human contributions to landslide hazards?
Modification of slopes (loading, cutting, drainage), artificial slopes, land degradation, triggers and encroachment.
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What are the types of slope failure?
Rotational and translational landslide, block slide, rockfall, topple, debris flow, debris avalanche, earthflow, creep and lateral spread.
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What are the characteristics of landslides?
Large boulders (km3) and high velocity (100s m/s) and a horizontal travel distance.
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What are the classifications of landslides?
Type of movement; fall, topple, slide, spread and flow. Type of material; rock, soil, snow/ice. Combinations and transformations.
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What are sensitive quick clays?
Marine clay; Na + binding with silicates. Salt leaching catastrophic loss of strength 30 times less resistance.
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What is the difference between earthflow and debris flow?
Earthflow consists of fine sediment but debris flow is a mix of particles.
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What are avalanche factors?
Temperature, slope gradient, aspect, wind direction, terrain, vegetation and snow pack conditions.
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What is a megahazard?
Unexpected or unprecedented in; type, size and place.
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What is a recurrence interval?
Recurrence events through time - logarithmic scale from hours to million of years.
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What are type/s of megahazards?
Super-eruptions and extra-terrestrial hazards.
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What is a volcano edifice collapse?
Collapse of a significant part of the volcano as well as slope failure.
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What are extra-terrestrial hazards?
Asteroid and comet impacts.
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What is the evidence for extra-terrestrial hazards?
All of them.
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Why are myths created?
All of them.
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What are common themes that result in the birth of myths?
All of them.
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What are the conservation of principles?
All of them.
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Who mythologised about Atlantis?
Plato
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What are some ENSO impacts (further afield)?
All of them.
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What is the North Atlantic Oscillation?
Large scale changes in Iceland and Azores pressure systems .Strong influence on winter weather.
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What type of radiation is solar?
Shortwave radiation.
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Other cards in this set

Card 2

Front

How many occur in USA, UK and Bangladesh?

Back

USA 900, Bangladesh 250 and UK 34.

Card 3

Front

In the USA what is the comparison between tornado events to hurricanes?

Back

Preview of the front of card 3

Card 4

Front

How can tornadoes be measured for their intensity levels?

Back

Preview of the front of card 4

Card 5

Front

What are the comparisons between Bangladesh tornadoes vs cyclones?

Back

Preview of the front of card 5
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