1GB1: Hazardous Earth Flashcards
What can tropical cyclones also be known as?
Hurricanes
Cyclones
Typhoons
What do the seawater temperatures have to be for tropical cyclones to form?
26.5 degrees C
What is the low pressure characteristic of tropical cyclones?
Very warm, most air rises through atmosphere, sucking up more air behind it
What is the rotation characteristic of tropical cyclones?
The earths spin helps rising air to spiral and drags in strong winds
What is the structure like of tropical cyclones?
Form a cylinder of rising, spiralling air
They are up to 640km wide and 10km high
Where do tropical cyclones start?
Warm water - tropics
Where do tropical cyclones move
Move westwards because winds blow from east around the equator, and they spin away from the equator
How can tropical cyclones change direction?
If cyclones reach a belt of winds blowing from west
How fast can tropical cyclones travel
640km/day
Where around the equator is the source area of most tropical cyclones?
5 degrees and 30 degrees north and south of the equator - any lower from the equator and the water is not warm enough
The majority of cyclones occur when sea temps are highest - when is this in the northern hemisphere?
June to november
The majority of cyclones occur when sea temps are highest - when is this in the southern hemisphere?
November to april
What processes occur in tropical cyclones?
Warm, most air rises
Condensation occurs
These release huge amounts of energy - making the storm powerful
How can cyclones intensify?
Due to energy from the warm water
When can cyclones dissipate?
When they move over land, cooler water because energy supply from warm water is cut off
Changes in windspeed by meeting other weather systems
What factors can cause tropical cyclones source areas to change?
Climate change - sea temps rise. Most of the world’s oceans could become above 26.5 degrees C
How long do tropical cyclones usually last?
7-14 days
What is the centre of the cyclone called?
The eye
What are characteristics of the eye?
Up to 50km across
Caused by descending air
Low pressure
Light winds
No clouds
No rain
High temp
What is the eye surrounded by?
The eyewall
What are characteristics of the eyewall?
Spiralling rising air
Very strong winds
Storm clouds
Torrential rain
Low temp
What happens towards the edges of the cyclone?
Wind speed falls
Clouds become smaller and more scattered
Rains less intense
Temp inc
Which direction do tropical cyclones spin in?
Anticlockwise in northern hemisphere
Clockwise in southern hemisphere
From which 2 geographical poles do tropical cyclones move to?
East to West
What physical hazards can tropical cyclones cause?
High winds
Intense rainfall
Storm surges
Coastal floosing
Landslides
How can physical hazards of tropical cyclones impact people?
People might drown in strong currents
Windspeed can destroy buildings
Debris can injure/kill
Electricity cutoff
Sewage contamination
Shortage of clean water and sanitation
Shortage of food
Unemployment
Damaged roads
How can physical hazards of tropical cyclones impact the environment?
Trees uprooted - damaging wooded habitat
Erode beaches
Pollute freshwater with seawater
Landslides
Damage industrial buildings - flooding
Oil/chemical leaks - pollution
How can countries be physically vulnerable to tropical cyclones?
Low lying countries are vulnerable to large waves
Areas in the path of cyclone are hit more frequently
Steep hillsides may increase landslide chance
How can countries be economically vulnerable to tropical cyclones?
Poorer countries:
People may depend on agriculture which becomes badly effected
People may not have insurance to cover costs of repairing damage
Both:
Buildings/infrastructure damage
How can countries be socially vulnerable to tropical cyclones?
POORER COUNTRIES:
Buildings are poorer quality
Health care not as good
Little money for flood defence or trained emergency teams
Harder to rescue people - poor infrastructure
How can tropical cyclones be forecasted?
Scientists can use:
- weather forecasting
- sattelite technology
- computer models to identify predicted paths
- magnitude: windspeeds
Why is it important to be able to predict whena. Tropical cyclones will occur and where?
To give people time to evacuate and protect their homes and businesses
How can the people be evacuated from tropical cyclone areas?
Warning strategies - alerts to leave homes
Governments make evacuation routes
Emergency services can train and prepare for disasters - rescuing through helicopters
Why is it important to have successful evacuations for areas with tropical cyclones?
Reduce number of deaths and injuries
How can areas be defended from tropical cyclones?
Defences can be built to prevent damage - sea walls
Reduces buildings destroyed - reduces killed, injured, homelessness and employment
What was hurricane Katrina?
In august 2005
Caused 1836 deaths in Louisiana, USA, Mostly in new orleans
What was the main reason of deaths from hurricane Katrina?
Failures in storm surge defences. The new Orleans levee sustem was old and wasnt maintained.
Evacuation had problems, highways out of new orleans jammed
Public transport not used
Shelters didnt have enough food
What improvements have been made since Huricane Katrina?
All the citys levees have been made much higher and stronger
The lake borgne barrier was made to protect new orleans (largest in the world)
New funding on search and rescue teams and now people get evacuation messages through text
What was cyclone Nargis?
May 2008 in Myanmar (Burma)
Caused 138,866 deaths
Category 5
What did Myanmar do to forecast Cyclone Nargis?
It had been tracked by weather forecasters in Indi and Bangladesh who informed Myanese government
How many people became homeless after Cyclone Nargis?
1 million
What was the evacuation like in Cyclone Nargis?
No evacuation procedures
No defences against storm surges
Houses made of weak materials
How did the government aid the people after Cyclone Nargis?
Government had limited ways of helping the 2.5million people affected
BUT
Still refused to let foreign aid workers to help for a week
What has the government now done after Cyclone Nargis as an improvement?
International aid built much stronger schools, homes and hospitals
Local communities have special committees to organise evacuations
The government built 20 cyclone shelters
2 people in each community given phone to relay cycloe warnings
Plans to regrow magrove forests to protect coast
What makes a cyclone category 5?
Winds at least of 254km/h
What makes a cyclone category 4?
Winds of 159-204km/h
