Storm hazards Flashcards
Give the 5 factors that cause storm hazards.
Sea temps at 26.5 degrees C.
5-30 degrees north or south of equator
coriolis force
low pressure (warm, moist air)
low-level convergence of air.
What is the Coriolis force?
The rotation of the Earth. Has to be at least 5% out of equator to spin/twist.
Spins to right in northern hemisphere, to the left in Southern.
What is the low-level convergence of air?
Different directions of trade winds converging, causing air to rise vertically.
Surface depressions caused by rising air increase the strength of trade winds.
Outline the stages of formation of Tropical Revolving Storms.
1) water evaporates + condenses, forming cumulonimbus clouds.
2) low air pressure meets with high air pressure (low level convergence), creating a surface depression.
3) there is an eye, eye wall and vertex
4) Coriolis effect creates spinning and storm is complete.
Give 3 primary storm impacts
High winds
Heavy rainfall
Storm surges
What is the average wind speed needed to create a TRS? (Tropical Revolving Storm)
75 mph.
means:
infrastructure damage
flying debris
disrupted transport
power outages
fires
Give the description and effects of an TRS’ heavy rainfall:
Average 200mm rainfall every few hours.
Convectional rainfall.
Hurricane Katrina (at peak) dropped 400mm rain in 1 day!
Creates secondary hazards (floods, landslides).
Give detail of TRS (Tropical Revolving Storm) storm surges
Average 3m high
caused by low atmospheric pressures and powerful surface winds.
What are the effects of storm surges?
Ruined agricultural lands
pollute water supplies
coastal erosion
Infrastructure destroyed.
Give 3 secondary hazards
Flooding
landslides
earthquakes (85% of magnitude 6 + above quakes occured within 4 years of a very wet storm.
Summarise the conditions that will define a category 4 storm
Windspeed = 131mph
Air pressure = 944 mbars
storm surge = 13ft
damage level = extreme.
Preparation methods for a storm hazard:
education
hurricane tracking
monitoring sea temps
evacuation
forecasting
preventing a storm hazards
CANNOT BE DONE.
Cloud seeding has been tried but effectiveness is not proven.
Adaption measures to a storm hazard
Buildings made with reinforced concrete.
sea walls
levees (Katrina)
Land zoning - houses away from coastal areas, trees planted away from house.
Mitigation in a storm hazard:
emergency survival kits
Insurance
strengthen roof/garage doors etc…
Levees.
Define Willy-willies
Name for tropical storms in north east and north western australia
What is the scale used to measure tropical storms?
The Saffir - Simpson - Scale
Categories 1-5
Define a ‘high pressure system’:
A system with higher pressure at its centre than the areas around it. Wind blows away from high pressure.
Define Global Atmospheric Circulation (GAC)
World-wide system of winds - necessary transport of heat from tropical to polar latitudes is accomplished.
Each hemisphere = 3 cells (Hadley cell, Ferrel cell and polar cell) in which air circulates through entire depth of troposphere.
What it the TROPOSPHERE?
The lowest layer of the atmosphere of the earth.
What does ITCZ stand for?
Inter-Tropical Convergence Zone (zone near the equator where trade winds meet)
Recieves most intense heat from sun. brings low pressure zones crucial to formation of storms. Exact area changes seasonally.
Why do TRS loose energy when they reach land?
Friction
lack of water.
How does human induced climate change impact TRS?
Spatially, sea temps will rise so increased distribution
Temporally, frequency of TRS does not change.
Increased INTENSITY (sea temps increase, more evaporation, more convection, more latent heat, which powers a storm).
What is FEMA?
