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WEATHER & CLIMATE (tropical cyclones (characteristics (strong winds,…
WEATHER & CLIMATE
tropical cyclones
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impacts
physical: damage to transport and communication networks
- affects efficiency of emergency actions
economic: repair costs and loss of agricultural income, temporary unemployment due to destroyed offices and food shortages due to destroyed farmlands
- food aid is often provided but can have economic backlashes on LDCs
economic losses due to tropical cyclones projected to increase due to population growth and climate change
social: disruption to water supply and sanitation facilities, contamination and spread of water-borne diseases + insect-borne diseases due to stagnant water + displacement from homes
responses
emergency action: depends on
- efficiency of local government
- effectiveness of communication systems
- education of the public --> evacuation areas and routes and importance of cooperation
mitigation
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land use control requires effective government and coorperation of locals
conversion of land requires financial capacity
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weather conditions
temperature
latitude: the distance of any point on the earth measured north or south from the equator
determines climatic zones --> global scale
lower latitude = higher solar angle = higher concentration of sun's rays
higher latitude = lower solar angle = sun's rays more spread out
daily/monthly/annual temperature
altitude: the height of a place in relation to sea level
temperature decreases by 6.50C every 1000m increase in altitude
- further from the earth's surface (shortwave radiation)
- air that is nearer to the earth's surface absorbs more heat from longwave radiation than air at higher altitudes (greenhouse gases)
- dense air is more able to absorb heat from longwave radiation
daily/monthly/annual temperature
distance from the sea: sea has a higher SHC than land, thus it requires more energy to heat up the sea than it does land and the sea heats up and cools down more slowly
- AIR above the surfaces of inland vs coastal areas
annual temperature range
cloud cover: (day) reflects sun's energy back into space
(night) absorbs longwave radiation, trapping it in the atmosphere
diurnal temperature range
relative humidity: the ratio between the actual amount of water vapour present in a mass of air and the maximum amount of water vapour the air can hold at a given temperature sling psychrometer
when RH=100%, saturation occurs at dew point temperature and water vapour condenses on condensation nuclei and coalescence occurs to form clouds
convectional rain: as the hot expanded air rises to a higher altitude, it will cool until it reaches dew pt temp. to form cumulonimbus clouds ; within the Tropics all year round, and during summer
relief rain: warm and moist air in the prevailing wind direction from a large water body up the windward side of a mountain body, dry air on leeward side
air pressure: the force exerted on a unit area of the earth's surface by the weight of a column of air above it
air pressure decreases as altitude increases
wind: the movement of air from a higher air pressure to a lower air pressure
greater difference in air pressure = faster wind speed
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climatic types
monsoon: between 5-25 degrees N/S of the Equator,
- high mean annual temp, but lower than eq. climate, small annual temp. range
- distinct wet and dry seasons
cool temperate: near coastal areas, 40-60 degrees N/S of the Equator,
- small annual temp. range due to maritime and continental effects, mild winters and cool summers
- rainfall evenly distributed around the year, 300-900mm, no distinct wet or dry seasons
equatorial: 10 degrees North/South of the Equator, within the Tropics,
- high mean annual temperatures ~27deg throughout the year, small annual temp. range of 2deg
- convectional rain, total annual rainfall >2000 mm, throughout the year w/o distinct wet and dry seasons
climate change
natural causes
variations in solar output: sunspots are cooler regions on the sun's surface that are compensated by the surrounding areas radiating more energy, resulting in higher solar radiation
(approx 11 year cycle)
volcanic eruptions releases sulfur dioxide in the air that reacts with water to form sulfate aerosol, which reflects solar energy back into space, resulting in global cooling
temporary because the particles will eventually settle and temperatures will return to normal
anthropogenic causes
changing land use and burning of fossil fuels as world population increases, more agricultural and industrial land is required for urbanisation and more fossil fuels are burnt to meet energy demands. the high carbon content in fossil fuels results in their combustions releasing large amounts of CO2, which is a greenhouse gas + constructing infrastructure
deforestation emitted during the deforestation process + fewer trees to absorb CO2 from the atmosphere
carbon-rich soil (from decomposition of organic matter) is exposed during deforestation and oxidises to produce CO2
agriculture machinery releasing CO2, inorganic fertilisers releasing nitrous oxides, livestock and decomposition of organic matter releasing CO2
industries production of goods and services involving the burning of fossil fuels, releasing CO2
impacts
sea level rise due to melting glaciers, affects coastal areas, global scale
more frequent extreme weather events financial capacity of the country to cope with economic losses of illnesses/destruction, DCs vs LDCs
spread of infectious insect-borne diseases heavy rainfall, increase in stagnant water as mosquito breeding grounds, global scale
affecting the growing season of certain crops can be advantageous! when seasons are lengthened, and when new crops can be grown due to the warmer temperatures
also disadv. when crops can no longer be grown due to the warmer temp.s
significant for LDCs that rely heavily on agriculture
shortwave radiation: heat radiated from the sun
longwave radiation: heat emitted from the earth's surafce
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