Y12 MB - Storm Hazards Flashcards
What are tropical storms?
Intense low-pressure systems that develop in the tropics
Give some different names for tropical storms
Hurricanes
Cyclones
Typhoons
What are the conditions required for a tropical storm to form?
Surface sea temperature 27°C or over
Low wind shear
Between 5° and 25° N and S of the equator so the Coriolis Effect is strong enough
In the Intertropical Convergence Zone (rising warm air)
What is the process of the formation of a tropical storm?
Around the tropics, atmospheric disturbance such as a storm event causes warm moist air to rise —> cools and condenses to form clouds
Condensation releases latent heat energy that creates further warming and rising moist air
This creates an area of low pressure so tall cumulonimbus clouds form
Low pressure results in strong winds that blow towards the equator —> along with the coriolis effect the storm starts to spin
As storm spins and moves over warm oceans the latent heat released from rising moist air fuels the storm (air moving up at the sea surface and out from the top creates a central vortex)
What does the process of condensation release?
Latent heat energy
What happens when a tropical storm reaches land?
It loses its source of energy
Friction with the land surface
Causes the storm to become less powerful and break up
Are tropical low or high pressure weather systems?
Low pressure
What are conditions like in the storm eye?
Calm conditions, higher temperatures, clear skies (rising air)
Where are the most powerful and dangerous conditions of a tropical storm?
The eye wall
What are wind speeds like in tropical storms?
High
Average wind speeds are 150km/h and can exceed 250km/h at the eye wall
How are storm surges associated with tropical storms?
Account for 90% of deaths by tropical storms
Occur when the ocean heaves upwards as a result of the low atmospheric pressure and combines with the wind-driven waves at the shore
Tropical storms can result in coastal and river ———— (describe)
Flooding
Can be caused by storm surges but flash flooding also due to torrential rain (often in excess of 200mm in a few hours)
More serious in urban areas where ground surfaces are impermeable
How are landslides related to tropical storms?
90% of landslides due to heavy rainfall (many due to tropical storms)
When sloped areas become saturated by rainwater the cohesion between the rock and soil particles weakens which causes the slope to fail
The additional weight of water also increases the risk
In which areas are tropical storms the most common?
1/3 in Southeast Asia
Followed by north-west and north-east Australia
How are tropical storms measured?
Using the Saffir-Simpson scale
5 point scale based on central pressure, wind speed, storm surface and damage potential
Why is the Saffir-Simpson scale limited?
Does not take into account the amount of rainfall or the area affected by the storm (remote or dens,ey populated)
What are the wind speeds of a category 5 tropical storm?
Over 250km/h
What are the wind speeds of a category 1 tropical storm?
120 - 150 km/h
Will climate change lead to an increase in the number of tropical storms per year?
Scientists are not sure - need more years of data to analyse
Will climate change lead to more intense tropical storms?
Warmer sea temperatures could lead to tropical storm wind speeds to increase which leads to more damage
Rising sea temperatures could also lead to a more powerful storm due to more fuel for the storm of rising moist air
Will climate change lead to more widespread tropical storms?
As sea temperatures of rising, the tropical are moving further towards the poles so this may mean that more areas have surface sea temperatures of above 27°C so areas further north and south of the equator could be affected
Can tropical storms be predicted?
They occur between 5° and 20° of the equator
Satellites provide data about wind speed and direction
Mainly occur in the late summer and autumn
Give some mitigation strategies for the impacts of tropical storms
Structural responses such as soft and hard engineering schemes - afforestation along the coast and the construction on sea walls to pretext coastal communities
Disaster aid - immediate relief (search and rescue, food, shelter etc and long-term aid (reconstruction and recovery)
Insurance cover - may only be available for the richest people (issue in the aftermath of Hurricane Katrina in New Orleans in 2005)
