tropical storms

Question 1

what is global atmospheric circulation?

Answer 1

cells= interconnected circular air movements
- sinking air creates high pressure
- rising air creates low pressure
- surface winds move from high to low pressure, transferring heat and moisture from one area to another
- these winds curve due to the earth’s rotation and change seasonally as the tilt/rotation causes relative changes in the position of the sun

Question 2

what is a tropical storm

Answer 2

huge storms called hurricanes, cyclones and typhoons in different parts of the world

they form 5-15 north and south of the equator in summer and autumn when:

• ocean temps are highest
• the spinning effect of the earth’s rotation is high
• intense heat and humidity makes the air unstable

Question 3

how do tropical storms form?

Answer 3

• rising air draws evaporated water vapour up from the surface
• it cools and condenses to form clouds
• condensing releases heat which powers the storm and draws more water vapour
• multiple thunderstorms join to form a giant rotating storm
• coriolis forces spin the storm at over 120km/h creating a vast cloud spiral
• which has a central, calm eye of descending air
• prevailing winds drift the storm over the ocean surface, gathering strength as it picks up more heat energy
• on reaching land, the energy supply is cut off and the storm will weaken

Question 4

will climate change affect tropical storms?

Answer 4

• over the last few decades, sea surface temps have risen by 0.25-0.5
• tropical storms may extend to the south Atlantic
• may become more powerful
• in the North Atlantic, 6/10 most active years since 1950 have happened since 1990
• in the North Atlantic, hurricane intensity has risen in the last 20 years

Question 5

what is the structure and features of a tropical storm

Answer 5

centre- eye
- column of rapidly sinking cool air
- no clouds
- calm conditions

eye wall
- most severe conditions
- strong winds
- torrential rainfall
- tornadoes can be formed here
- up to heights of 15km

beyond eye wall
- further banks of clouds and thunderstorms
- occasionally tornadoes
- strong gusty winds, heavy rain

Question 6

hurricane Idai, Mozambique

Answer 6

-March 2019
- Africa’s deadliest tropical cyclone on record
- port city Beira

primary effects
- torrential rain (600mm)
- 1300 killed
- 3mil affected
-90% of Beira was destroyed by strong winds
- 17 hospitals damaged
- lost power, roads flooded
- flash flooding destroyed 600 houses in Zimbabwe

secondary
- rivers overflowed in Mozambique and Zimbabwe
- floods up to 6m deep
-700,000ha of crops destroyed
- mudslides hampered rescue efforts
- Malawi- floods caused dams to collapse- 2 HEP damaged
- outbreaks of cholera- 4000 cases in Beira caused by lack of sanitation/clean water

Question 7

Mozambique responses

Answer 7

immediate
- boats and helicopter rescues
- 140 evacuation centres set up to help 125,000 displaced people
- UN dropped off food, volunteers

long term
- new buildings designed to withstand disasters
- early warning system improvements
- CAFOD spent £2mil supporting families/communities and rebuilding schools, agricultural advice