challenges of natural hazards- weather hazards- tropical storms Flashcards
what is a tropical storm?
a huge spinning storm which has developed in the tropics.
How are tropical storms formed?
1) Warm moist air rises and leaves low pressure under. Brings with it large amounts of water vapour which causes strong winds. Constant cycle that surrounding air fills into the low pressure area left behind.
2) The evaporated warm air later cools as it rises and then condense and form large thunderstorm clouds
3) The Coriolis effect causes the air to spin and the constant addition of energy from the warm air (as the air condenses, it releases heat which powers the storm as draws more water up from the ocean) causes the storm to spin faster and faster and generate higher wind speed. Soon the storms surface winds will reach an average of 75mph and this is when it is officially classed as a tropical storm.
4) The storm then developes an eye in its centre and this is where an area of extremely low pressure is and where cool dry air descends rapidly. The weather in the eye is relatively calm and cloud free. The outer edge of the eye is the eyewall where the most intense weather conditions (strong winds and heavy rain) are felt. The storm is carried across the core an by prevailin*winds and continues to gather strength.
5) When the tropical storm reaches a coats, the low pressure and high winds will cause a large amount of sea water to be pushed onto the coast and this is called a storm surge. However, when the storm reaches land, the storm will no longer have a supply of energy (the warm air and moisture from sea) and the friction with the land slows the storm and weakens it as well. Eventually, the eye collapses and the storm dissipates but heavy rain could persist for days. If the storm reaches warm sea after crossing the land, it may pick up strength again.
why does a tropical storm spin?
The corolisis effect bends and spins the rising air.
what direction do teh storms travel?
East to west due to the direction of the earth spins. Tropical storms in the northern hemisphere track north and storms in the southern hemisphere track south
what is the corolisis effect?
Due to the earths curvature shape, the equator is much wider than the poles. therefore teh earth spins faster at the equator. This difference in speed means that wind bends as it blows accross the earth.
Where do tropical storms form?
They occur in the tropics, foun in areas 5-30 degrees nirth and south of the equator.o
How might climate change effect tropical storms?
-Temp increase=sea level rise due to thermal expansion. Rise sea level= storm surge becomming higher
-Warmer atmosphere = higher ability to retain more moisture. Rainfall is also expected to increase = flooding is more likely. Storms are also expected to become more destrcutive
- Intensity and frequency: The overall frequency of the number of tropical storms occuring is epected to decrease or stay the same. However the number of severe tropical storm is expected to increase. \
- distribution: As sea temp rises, areas that storms do not usually form may potentially ahve an increase in storms because of the sea being warm enoyghto provide enough energy for one to form.
how are tropical storms measured?
using the saffir simpsons scale from 1 -5
what are the conditions needed for a storm to form
Ocean temp of 26-27+
Wind must be present to create the swirling motion
5-30 degrees north and south of equator (as there needs to be a rotation motion in order for the corolisis effect to happen)
There must be an unstable air pressure
what are the effects of tropical storms
primary = P
secondary = S
Storm surge damages buildings (P) = homelesness (S)
Crop shortages (P) = Fppd shortages
Electricity and communications damaged (P)
Heavy rain causes freshwater flooding (P)= drinking water contaminated and blocked roads (S)
How does monitoring, prediction, protection and planning help?
1) Monitoring:
This is the detecting and recording of warning signs for a stor formation. They allow predictions to be made and reduces the damage caused.
eg
satilites track cloud formaton and movement
some specially equipted aircrafta re flown into the storm and tey release dropsomders which shed measurements every second by radio back into the aircraft.
2)Predicting:
It is possible to predict the royte pf teh storm as well as intensity. Predictions become more reliabel as the storm nears. By analysing the intensity, we can estimate how large the storm surge is wich is important for making decisions on risk factors and places which need evacuating.
3) protection: It is unrealistic to stop people from living in coastal areas as they depend on them for a living. However we can plan ahead and create evacuation routes s well as educating people on how to prepare for the next hurricane season.
what is the case study for tropical storms?
typhoon hiyan (takaloban)
stuff on the case study:
- catagory 5 typhoon
-sea level surge of 6 meters - predicted to be one of the strongest tropial cyclone ever recorded.
- clased as a supper cyclone
effects:
- 14 million people affected in which there was looting because of shortage in food, water and shelter
- almost 3 billion in damage
- around 90% of Tacaloban destroyed
- Flood of around 20ft deep due to the surge and tehre were diseases such as malaria becasue the water attracted mosquitoes
- Overwhelmed clinics
Response:
- around 1500 evacuation centres
- red cross provided clean water and survival tips
1 Royal Air force delivered over 200tonnes of aid such as rice
- shelters were made for the homeless
-World health organisation vaccinated chilkdren against diseases
In August 2017, Houston in Texas was badly flooded by Hurricane Harvey. One of the many effects was 460,000 gallons of gasoline escaping from a refinery. How would you classify this chemical leak event?
It is a secondary effect because The leak was triggered by a separate primary effect – in this case, damage to the refinery pipes and buildings.
what are trade winds?
Trade winds are persistent winds that blow towards the equator from the subtropical high-pressure belts located at about 30° north and south.
