Typhoon

Question 1

What is a typhoon? What usually is associated with it?
Describe the structure of a typhoon.

Answer 1

1. Typhoon (tropical cyclone) = strong tropical storm, low-pressure system that develops over tropical water
2. Very strong winds, dense clouds, heavy rain, storm surge & lightning
3. Eye (Centre of a typhoon), calm & no clouds ; strong winds & heavy rains ONLY outside eye

Question 2

What are the weather conditions / changes brought by a typhoon?

Answer 2

1. Temperature decreases 2. Air pressure decreases
2. Wind speed increases 4. Precipitation(s) (e.g shower)

Question 3

Most of the typhoons that affect Hong Kong and the eastern coast of Asia are formed over the (1) near the (2) . Typhoons can also be formed over other (3). Typhoons move (4) after they are formed.

Answer 3

1. Pacific Ocean
2. Philippines
3. warm tropical oceans
4. towards the west

Question 4

What are the 2 favorable conditions that tropical oceans offer for a typhoon to form?

Answer 4

1. Warm water with surface temperatures over 26.5°C
2. An abundant supply of moist air

Question 5

How does a typhoon formed?

Answer 5

1. Near the equator, warm tropical ocean with over 26.5°C
2. Warm, moist air near the ocean surface rises and cools
3. Air condenses to form clouds releasing heat to the surrounding air
4. low-pressure centre is formed over the ocean and draws more moist air
5. As there is abundant supply of rising air, towering clouds are formed
6. The clouds spin around the eye and spiral upward as it rises.
7. A typhoon is formed which sucks in more warm and moist air.

Question 6

On average, How many typhoons affect Hong Kong each year?
What are the effect of typhoons?

Answer 6

Around 6 typhoons affect HK per year

Strong winds, heavy rain & storm surges brought by typhoons may lead to…
1. Disrupt to economic activity (e.g loss of crops & business closures)
2. Loss of property (e.g damage to buildings & infrastructure)
3. Injuries & deaths
4. Other natural hazards (e.g landslides & coastal floods)

Question 7

What are the preventive measures for typhoon?

Answer 7

1. Constructing typhoon-proof buildings
   
   • 4 sided roof less likely to be lifted away by wind than 2 sided roof
   • made of concrete to increase strength
   • build on stilts to protect house from floods
   • tempered glass with shatter-resistant film
2. Adopting better land use planning
   
   • move settlements from coastal areas further inland —> reduce damage of storm surges
3. Setting up monitoring & warning systems
   
   • e.g typhoon warning signals
4. Educating people to take precautionary actions

Question 8

What are the remedial measures for typhoons?

Answer 8

1. Having well-trained rescue teams to provide medical care
2. Providing temporary shelters, emergency & financial aid

Question 9

How does a typhoon “die”?

Answer 9

1. As they travel over cold water or reach land, supply of warm & moist air cut off
2. friction: on land surface > sea surface
3. The typhoon reduces its energy & dissipates