Component 1 - Topic 1: Hazardous Earth Flashcards
What are the two ways heat is transferred around the energy ?
- Winds + Global Atmospheric Circulation Loops (cells)
- Ocean Currents
How does the wind coupled with cells transfer heat around the Earth ?
- Most heat is received at the equator, the hot air rises and moves out to 30 degrees North and South
- The air cools as it rises and drops again, as it drops the air is either moved back to the equator or towards the poles by surface winds
- -Winds blowing towards the equator are called trade winds
- -Winds blowing towards the poles are called westerlies
- This process happens again between 30 degrees and 60 degrees and at 60 degrees and the poles
How is heat transferred by Ocean Currents ?
- Water freezes at the poles causing the surrounding water to get saltier, this increases its density
- As the density of the water increases, it sinks
- This causes warmer water to flow to the surface, this creates a current
- The warm water cools as it rises closer to the surface, this repeats the cycle
What effect on the Earth do ocean currents have ?
Ocean currents keep areas warmer than they would normally be, for example the Scilly Isles located of the coast of the UK have a relatively warm climate and on the same line of latitude, St. Johns Newfoundland in Canada experiences lots of snowy weather every year
How and where do Tropical Cyclones form ?
- Cyclones normally form between the tropic of Cancer and Capricorn, 23.5 degrees North and South
- When temperatures of the sea reach 26.5 degrees celsius, lots of water begins evaporating, rising and condensing
- The rise in air with the water vapour creates a draft which causes more air to rise
- The air condenses which releases lots of energy, the rise in air also creates low pressure which increases wind speed
- The Coriolis force (created by the rotation of the Earth) causes the cyclone to spin
- As the air rises and cool is falls in the centre of the storm, this is called the eye of the storm. Inside there are light winds, no clouds, no winds and warm temerature
Why do cyclones increase and decrease in intensity ?
Increase:
-Warm water, this provides more energy to the cyclone
Decrease:
-Lack of warm water to supply the storm with energy
What are some physical hazards of cyclones ?
Hazards: High winds, Intense Rainfall, Storm surges, Costal flooding, landslides ^These can cause: -Damage to environment -Damage to infrastructure -Loss of lives
Why are some countries more vulnerable to impacts of tropical cyclone ?
May have:
- Greater amount of reserves of - or areas of - fragile ecosystems
- Greater population leading to more people at risk
- More expensive infrastructure leading to greater economic risk
- Less wealth, this means the countries are less likely to be able to recover and or prepare for the cyclone
How can countries prepare for the effects of a tropical cyclone ?
Forecast/Tracking: predicting when the cyclone will arrive may give people enough time to make further preparations and evacuate
Building Design: Buildings may be specially designed to resist the impacts of the cyclone and minimise damage done
Compare the preparation and response to 2 named cyclones in developed and developing countries
USA, New Orleans, Katrina:
-National Hurricane Centre in Florida detected the Cyclone 3 days in advance and issued a warning for people to evacuate:
–1,800 people killed, 300,000 houses destroyed and 230,000 jobs lost
-About 70%/80% of the population evacuated
-Flood defences (embankments) failed and 80% of the city was submerged underwater
-New Orleans recovered fully in about 2 years
Myanmar, Nargis:
-Indian weather agencies warned Myanmar, Myanmar’s government issued a warning over tv, but the majority of people in Myanmar do not have a tv
-No evacuation: 140,000 people killed, 450,000 houses destroyed, 65% of rice paddies destroyed, Lack of sanitary conditions led to the spread of many diseases
What are the 3 layers of the Earth ? Briefly describe them
Core:
-At the center of the Earth
-Very dense and made of solid (inner) and liquid (outer) iron and nickel
-About 5000 degrees celsius
Mantle:
-Located around the core
-Made up of silicon-based rocks
-Upper layer is called the Asthenosphere which is semi-molten
-The very top part is rigid
Crust:
-Made of silicon-based rocks
-2 types of crust; continental and oceanic:
–Continental crust is thicker but less dense
–Oceanic crust is thinner but more dense
How do convection currents in the mantle move tectonic plates ?
- Radioactive decay of some elements occurs in the mantle and core, this generates lots of heat
- Lower parts of the asthenosphere heat up and become less dense and therefore start to rise
- As they move to the top they sink due to cooling down and becoming more dense
- This creates a circular movement which is known as a convection current
- This movement creates drag on the base of the tectonic plates which causes them to move
What are convergent boundaries ?
Convergent plate boundaries:
- When two plates move towards each other
- E.g. West coast of South America
- If a continental and oceanic plate collide then the oceanic plate is forced down into the mantle and destroyed
- -This sometimes creates volcanoes and ocean trenches
- If two continental plates meet then the plates collide and the ground folds up, forming mountain ranges
What are Divergent Boundaries ?
Divergent Boundaries:
- Where two plates are moving away from one another
- Magma rises and fills the gap in-between forming new crust
- E.g. mid-Atlantic ridge
What are Conservative Boundaries ?
Conservative Boundaries:
- where two plates are moving sideways on past each other in the same direction but at different speeds
- E.g. San Andreas Fault
