Chapter 1(II): 
QUIZ
DROUGHTS
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Pic source: http://www.wallingfordsoftware.co.uk/images/myths/droughts1.jpg |
Droughts are prolonged periods of lack of rain.
It may last for a week or even several years
E.g.: Sahel region, south of Sahara Desert - experience excessive evaporation, great heat and little rain.
Causes Of Drought
(i)
unusual warm ocean currents - which cause heatwaves.
(ii) man through activities such as deforestation and overgrazing.
Consequences Of Drought
1.
Desertification.
Desertification is the degradation of land in arid, semi-arid and dry sub-humid areas due to the influences of human activities and climatic variations on dryland ecosystems.
2. Famine
3. Food shortage & crop failure
Photo Gallery
FLOODS [Back to top]
 Pic source: http://www.users.bigpond.com/salaman/unley/marnws/ |
Types
Of Floods
(i) River
floods
- Occur when swollen rivers overflow the banks.
- Often caused by heavy rain or melting snow.
- E.g. Hwang He River, China
(ii) Coastal floods
- Occur when storms, high tides, tsunamis or sea surge flood coastal areas.
- E.g. Bangladesh and the Philippines
(iii) Seasonal floods
-Occur when streams overflow the banks during the wet season.
- E.g. Nile floods in Egypt
(iv) Flash floods
- Floods that occur suddenly, due to heavy downpour for several hours, or poor drainage system.
- E.g.: Brisbane, Kuala Lumpur.
Photo Gallery - Flooding
TROPICAL STORMS [Back to top]
Hurricanes, Typhoon, Tropical Cyclones & Willy Wilies
A. Formation of Tropical Storms
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Hurricanes form over warm tropical seas.
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Wind from opposite directions meet and begin to spiral upwards over an area of low pressure.
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Water vapour, carried from sea below, rises, becomes warm and forms cumulonimbus clouds.
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As air becomes warmer, it rises more quickly.
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This movement of rising air sucks in more air at the bottom and begins to spiral faster and faster.
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Wind speeds can reach up to 320km/hr.
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But the centre of the storm (the'eye') is a quiet, still area, with only light winds.
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Hurricanes only die out over land (when there is no water to supply to the storm).
B. Hurricane Areas
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C. Effects Of Tropical Storms On Coastal Areas
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Storm surge
Fast blowing winds can raise the sea level by about 1m beneath the 'eye', and creates a huge mound of water.
As a hurricane moves to the coast, the mound of water piles up against the land.
Destructive surge of water can rip boats and batter buildings.
Weblinks
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Effect - Video: virtually fly through a hurricane
(Real Media Player/Windows Media Player) -
Phenomena- Video: watch the formation of Hurricane Andrew
(Real Media Player/Windows Media Player) -
Science - video: a Florida homeowner talks about Hurricane Andrew's ordeal, satellite data animations of Hurricane Luis in progress
(Real Media Player/Windows Media Player)
E. Difference Between A Hurricane And A Tornado
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Tornado
Weblinks
Photo Gallery