Topic 1-Tropical Cyclones Flashcards
What is location of tropical cyclones
Mainly on equator and are mainly on atlantic pacific and indian ocean and in between tropic of cancer and capricorn.
Tropical cyclones track west (owing to easterly winds) and slightly towards the poles
Many tropical cyclones eventually move into areas dominated by westerly winds (found in the mid latitudes)
These winds will reverse the direction of the tropical cyclone to an eastward path
As the tropical cyclone continues to move poleward, it picks up speed and may reach 30 mph or more
Tropical cyclones can travel about 300 to 400 miles a day, or approximately 3,000 miles before dying out
Tropical cyclones mostly occur in the late summer to autumn when sea temperatures are at their highest
In the northern hemisphere, late summer to autumn is June – November
In the southern hemisphere, this is between November to April
Features of tropical cyclones
Tropical cyclones are rotating, intense low-pressure systems (below 950mb)
Characteristics include:
Lasting 7-14 days
Heavy rainfall
High wind speeds (over 119 kmh)
High waves and storm surges
Tropical cyclones can vary in diameter (100-1000km)
Winds spiral rapidly around a calm central area known as the eye, with descending cold air, low pressure, light winds, no clouds or rain
The winds of the storm are not constant across its diameter
The outer edges of the storm have lighter wind speeds, smaller and more scattered clouds, rain is less intense, and the temperatures begin to increase
The strongest and most destructive winds are found within the eyewall, with spiralling storm clouds, torrential rainfall and low temperatures
Tropical cyclones are rated on the five-point Saffir-Simpson scale based on wind speeds
Tropical cyclones are considered major when they reach category 3 and have wind speeds between 111-129 miles (178-208 kilometres) per hour
A category 5 storm can deliver wind speeds of more than 157 miles (252km) an hour
Formation of tropical cyclones
-strong clusters of thunderstorms drift over warm water at 26.5 degrees
- warm air from storm and ocean surface combine which create huge amounts of energy and begin rising creating lownpressure at surface which creates surface winds
- rising warm causes pressure to decrease at high altitudes and wind make them spin outwards
- air rises faster and faster drawing warm air off sea and cooler drier air downwards
- as storm moves collects more water and wind speed increase
- takes hours to become cyclone of an eye, low pressure surrounded by high winds and storm
-dissipate when they move over land or cooler water because energy supply from warm water is cut off so chnages in windspeed.
Impacts on tropical cyclones on people (storm surges,high winds etc)
Storm surges- contaminating farmland
High winds- homelessness and buildings damaged and injuries
Rainfall- damage to property and fast flowing water can cause injuries
Flooding- farming and toruism industries destroyed and causes sewages to overflow which conaminates wtaer so easier diseases to spread as shortsge of clean water
Landslide- home destroyed and death and dmages on roads so difficult for aid to occur
Impacts on tropical cyclones on environemnt(strom surges,high winds etc)
Storm surges- erode beaches and coastal habitats,damage coastal dfeneces and flow inland
High winds- treess blown over
Rainfall- flooding
Flooding- damaging salt water and can damage industrial buildings on coast such as oil factories causing harmful chemicals into environment and causes pollution
Landslide- blocked rivers as sediment deposited in lakes and rivers so can kill wildlife
Formation of tropical cyclone-2
Warm, moist air rapidly rises, forming an area of low pressure
Air from high-pressure areas rushes in to take the place of the rising air
This air then rises, forming a continuous flow of rising air
As the air rises, it cools and condenses. This releases heat energy, which helps power the tropical cyclone
Air at the top of the storm goes outwards away from the centre of the storm
The Coriolis force causes the rising air to spiral around the centre.
Some of the air sinks in the middle of the storm, forming a cloudless, calm eye
The tropical cyclone moves westward from its source
If a tropical cyclone makes landfall or moves over an area of cold water, it no longer has a supply of warm, moist air and loses speed and temperature; therefore, rainfall and winds decrease
Dissipation kf tropical cyclones
A tropical cyclone will dissipate if it loses its source of energy - either from the warm waters or loss of moisture over land
When a tropical cyclone makes land, the winds become slower as it passes over rough terrain and over built up areas
If a tropical cyclone stirs up deep, cold ocean waters, then it will lose energy and dissipate
Hazards of tropical cyclones
High winds up to 250km/h uprooting trees, damaging infrastructure, buildings, causing injury and loss of life
Intense rainfall leading to flash flooding, damaging property and injuring people from fast-flowing water
Storm surges from large areas of low pressure allowing the sea level to rise which, combined with high winds, forces a large mass of water towards land. This erodes beaches, damage sea defences and contaminates farmland and freshwater
Coastal flooding caused by intense rainfall and storm surges can affect large areas of low lying land including farmland and the tourist industry
Landslides are triggered because soil becomes saturated due to intense rainfall and in areas with steep slopes where the soil can no longer hold its position sliding down the slope
Primary and secondary impacts of tropical storms
Primary-secondary:
Buildings and bridges are destroyed-people are homeless,causing distress,poverty,ill-health or death due to lack of shelter. Cost of rebuild can be expensive and some people may have not have insurance
Roads,railways,ports and airports damaged-Blocked or destroyed roads prevent rescue and emergency vehicles, and aid from getting through
Electricity lines are damaged/destroyed-life support systems,hospitals,shops and homes left without power supplies
Gas lines broken-rise of fires and explosions
Sewage overflows-clean water supplied contaminated bringing increased risk of diseases and death
Rivers and coastal areas flooded-people drown or injured through rushing water. Crops,livestock and habitats destroyed,shortage of food and famine
Businesses destroyed-economic impact to business owners and potential unemployment
Vulnerability of tropical storms-physical,economic and social
Physical:
-low lying coastlines are vulnerable to storm surges,flooding and high winds
-areas where tropical storms from, are hit more frequently as they are in path of storm
-a high frequency of storms, leaves little time to recover from previous events
-steep slopes increase risk of landslides
-lack of infrastructure or accessibility to remote areas due to physical landscape
Economic:
-low levels lf development lacks of resources available to respond to storms or protect vulnerable areas from worst impacts of storm. Also buildings tend to be of poorer build quality and easily damaged
-financial costs of repairs can be too much for some countries, some people may not gave insurance
-the costs of repairs for developed countries will be higher as the infrastructure and buildings are more complex and damage are more intense
-countries with high levels lf development are less vulnerable due to accurate weather predictions,coastal defences to manage storms surges and evacuation procedures
-Harder to rescue people if infrastructure is damaged or is non-existent in some poorer countries
Social:
-old and young people are more vulnerable as they are more likely to struggle evacuating
-lack of education ,information, emergency planning and evacuation strategies can induce panic
-health and well-being are impacted regardless of wealth, but poorer countries struggle to treat injuries and provide basic support
-areas of poverty lead to poor construction of housing which is more easily damaged-regardless pf level of development
-poorer areas are less likely to have access to shelter,food and clean water and medical care
