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Key Question 1: Why do different places experience different weather and climate?
What is the difference between weather and climate?
What are the elements of weather?
· Elements of weather
– Temperature
– Air humidity, clouds and rainfall
– Pressure and winds
Why do different places experience different temperatures?
Why do places at the same latitude have different temperatures?
– Factors influencing the temperature of locations
○ Latitude
○ Altitude
○ Distance from the sea
○ Cloud cover
How is rain formed?
· Relative humidity, clouds and rainfall
– Relative humidity
– Formation of rain
○ Convectional rain
○ Relief rain
How are land and sea breezes formed?
How are monsoons formed?
· Pressure and winds
– Pressure and movement of air
– Wind systems
○ Land and sea breezes
○ Monsoon winds
What are the characteristics of equatorial climate, monsoon climate and cool temperate climate (marine west coast)?
Where are these climatic types experienced?
· Equatorial climate
· Monsoon climate
· Cool temperate climate: Marine west coast climate
Key Question 2: What is happening to the Earth’s climate?
How has global climate changed?
· Changes in climate
– Global records since 1880 show a significant, but irregular upward trend in temperature with fluctuations of 0.3°C to 0.6°C
– Global warming over the last century: world is warming on average by 0.74°C, with most of the increase since the 1970s
– Global temperatures in the last decade reached the highest levels on record
What causes global climate change?
What is the greenhouse effect and how does it work?
· Greenhouse effect is a natural process by which greenhouse gases trap heat in the atmosphere
What is the enhanced greenhouse effect?
· Human activities have contributed substantially to climate change by adding greenhouse gases to the atmosphere, hence enhancing the greenhouse effect
How do human activities lead to enhanced greenhouse effect?
Is climate change a result of natural or human courses?
· Natural causes of recent climatic change
– Variations in solar output
– Volcanic eruptions – cooling influence
· Anthropogenic factors leading to enhanced greenhouse effect
– Deforestation and associated increase in atmospheric carbon dioxide
– Changing land use and associated increase in greenhouse gases
○ Agriculture (e.g. burning of fossil fuels to provide energy to operate machines in rice farming, methane produced by cattle farming)
○ Industries (e.g. burning of fossil fuels to provide energy for manufacturing, greenhouse gases as by-products of manufacturing)
○ Urbanisation (e.g. burning of fossil fuels to provide energy for household activities and transport)
How does climate change affect people?
· Impacts of climate change
– Sea level rise
○ Threatens low lying areas and islands
– More frequent extreme weather events
○ Heat waves
– Spread of some infectious insect-borne diseases
○ Dengue fever
○ Malaria
– Lengthen the growing season in certain regions
○ Fruit production (e.g. in Eastern Canada)
○ Vineyards (e.g. Italy in Europe)
How do countries respond to climate change?
· Responses and challenges to climate change
– International agreements
○ Kyoto Protocol
Ø Clear targets for each country to reduce greenhouse gas emissions
Ø Countries accountable for meeting their targets
– National responses
○ Singapore - Strategies to reduce greenhouse gas emissions focusing on energy efficiency and energy conservation, new building requirements and technologies
Key Question 3: Is the weather becoming more extreme?
(*Focus is on tropical cyclones for PURE GEOG ONLY)
Where are tropical cyclones found?
· Occurrence of tropical cyclones
– 8–15° latitude from the Equator
– Warm sea temperature greater than 26.5°C
What are the characteristics of tropical cyclones?
· Characteristics of tropical cyclones
– Weather systems developing over tropical or subtropical waters. Also known as typhoons and hurricanes
– Strong winds exceeding 64 knots or 119 km/hr, circulate clockwise in the southern hemisphere and counter clockwise in the northern hemisphere while spiraling inward to the cyclone centre or eye
– Low pressure with clear skies and calm winds at the eye
What is the impact of tropical cyclones?
· Hazards associated with tropical cyclones
– Storm surges
– Strong winds
– Torrential rains
· Impacts of tropical cyclones:
– Physical
o Damage to infrastructure
o Disruption of communication
– Economic
○ Cost of repair to infrastructure
○ Loss of income due to ruined crops
– Social
○ Disruption to water supply
○ Spread of diseases
○ Displacement of people from their homes
· Emergency action
○ Weather warnings and advisories
· Mitigation measures
– Prediction and warning (e.g. based on analysis of satellite data, climatological records, computer models of cyclone activity and tracks)
– Land use control
o Coastal plain management
o Flood plain management
o Reducing vulnerability of infrastructure (e.g. wind and water resistant building designs, regular inspection of levees, river embankments and coastal dikes for breaches due to erosion, locating utility lines underground)
With reference to a case study of a tropical cyclone/typhoon, consider the following guiding questions:
1) When and where did it occur?
2) What were the weather conditions and the damages it inflicted?
3) How effective were the measures adopted to mitigate the impact?
4) Is responding to tropical cyclones a continuing challenge?
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