HAZARDS: Storm Hazards Flashcards
Tropical storms
Large spinning storms with strong winds + torrential rain.
What conditions are needed for a tropical storm?
- Disturbance near the sea-surfcae, eg. low pressure
- Warm water (above 27oC to at least 50m below surface) = lots of evaporation
- Convergence of air in lower atmosphere - forces warm air to rise
- At least 5o from the Equator, as this is where coriolis effect is strong enough
What are tropical storms in the Caribbean Sea called?
Hurricanes
What are tropical storms in the Bay of Bengal called?
Cyclones
What are tropical storms in the China sea called?
Typhoons
Why do tropical storms lose strength over land?
Supply of warm, moist air is cut off.
What do tropical storms initially do?
Move westwards due to easterly winds in tropics
Why do tropical storms move away from the equator?
Due to Coriolis effect.
How long do tropical storms usually last?
7-14 days
How do tropical storms spin in the northern hemisphere?
Anticlockwise
How do tropical storms spin in the southern hemisphere?
Clockwise
Describe the structure of a tropical storm:
- Area of low pressure at centre = eye
- Rising air spirals around eye in the eyewall, causing strong winds
- Outflow of moisture-laden air near top = cloud cover extends for a long distance
How are storms classified?
Using the Saffir-Simpson Scale, which is based on wind speed.
How does the Saffir-Simpson Scale work?
- Rates storm hazards on a scale from 1-5 (category 5 is the strongest)
- Estimates how much damage a storm of a given magnitude will do
Category 5
Stongest storm hazard.
Winds over 250km/h
Category 1
Weakest storm hazard.
Winds of 120-150km/h
Describe the frequency of tropical storms:
Around 100 a year.
Northern hemisphere - June to November
Southern hemisphere - November to April
Why can the path of a tropical storm be predicted fairly accurately?
Cloud formations can be identified by satellite imagery - shows formation of tropical storm.
Can then be tracked using satellites and models.
What are some of the forms a storm hazard can take?
High winds
Storm surges
Heavy rain
Flooding
Landslides
Storm surge
A large rise in sea level caused by high winds pushing water towards the coast, and by the low pressure of a storm.
How can the impact of storm hazards be reduced by prevention?
Cannot be prevented, but can be studied to identify high-risk areas.
Future developments can be planned to avoid these.
How can the impact of storm hazards be reduced by prepardness
- Emergency services cna train + prepare for disasters
- Evacuation routes can be planned
- Education
How can the impact of storm hazards be reduced by adaptation?
- Buildings can be designed to withstand storms + floods
- Flood defences can be built
