Storm hazards

Question 1

Give the 5 factors that cause storm hazards.

Answer 1

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.

Question 2

What is the Coriolis force?

Answer 2

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.

Question 3

What is the low-level convergence of air?

Answer 3

Different directions of trade winds converging, causing air to rise vertically.
Surface depressions caused by rising air increase the strength of trade winds.

Question 4

Outline the stages of formation of Tropical Revolving Storms.

Answer 4

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.

Question 5

Give 3 primary storm impacts

Answer 5

High winds
Heavy rainfall
Storm surges

Question 6

What is the average wind speed needed to create a TRS? (Tropical Revolving Storm)

Answer 6

75 mph.

means:
infrastructure damage
flying debris
disrupted transport
power outages
fires

Question 7

Give the description and effects of an TRS’ heavy rainfall:

Answer 7

Average 200mm rainfall every few hours.
Convectional rainfall.

Hurricane Katrina (at peak) dropped 400mm rain in 1 day!
Creates secondary hazards (floods, landslides).

Question 8

Give detail of TRS (Tropical Revolving Storm) storm surges

Answer 8

Average 3m high
caused by low atmospheric pressures and powerful surface winds.

Question 9

What are the effects of storm surges?

Answer 9

Ruined agricultural lands
pollute water supplies
coastal erosion
Infrastructure destroyed.

Question 10

Give 3 secondary hazards

Answer 10

Flooding
landslides
earthquakes (85% of magnitude 6 + above quakes occured within 4 years of a very wet storm.

Question 11

Summarise the conditions that will define a category 4 storm

Answer 11

Windspeed = 131mph
Air pressure = 944 mbars
storm surge = 13ft
damage level = extreme.

Question 12

Preparation methods for a storm hazard:

Answer 12

education
hurricane tracking
monitoring sea temps
evacuation
forecasting

Question 13

preventing a storm hazards

Answer 13

CANNOT BE DONE.
Cloud seeding has been tried but effectiveness is not proven.

Question 14

Adaption measures to a storm hazard

Answer 14

Buildings made with reinforced concrete.
sea walls
levees (Katrina)
Land zoning - houses away from coastal areas, trees planted away from house.

Question 15

Mitigation in a storm hazard:

Answer 15

emergency survival kits
Insurance
strengthen roof/garage doors etc…
Levees.

Question 16

Define Willy-willies

Answer 16

Name for tropical storms in north east and north western australia

Question 17

What is the scale used to measure tropical storms?

Answer 17

The Saffir - Simpson - Scale
Categories 1-5

Question 18

Define a ‘high pressure system’:

Answer 18

A system with higher pressure at its centre than the areas around it. Wind blows away from high pressure.

Question 19

Define Global Atmospheric Circulation (GAC)

Answer 19

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.

Question 20

What it the TROPOSPHERE?

Answer 20

The lowest layer of the atmosphere of the earth.

Question 21

What does ITCZ stand for?

Answer 21

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.

Question 22

Why do TRS loose energy when they reach land?

Answer 22

Friction
lack of water.

Question 23

How does human induced climate change impact TRS?

Answer 23

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).

Question 24

What is FEMA?