The following are notes I somewhat typed from the textbook, this
contains only the chapter 1 and chapter 2 gateway 1 for my
textbook, for sec 3 geography.
Some of the explanation may be wrong, as I did some my self.
its about 1800 words, should be helpful, contained most
stuff…
Natural hazard: a naturally occurring event that threatens lives
and causes damage to property. Tectonic:earthquakes, volcanic
eruptions, tsunamis. Climate related: droughts, floods, tropical
cyclones. Core: 3300 km thick, temp in 3000 to 5000. Mantle, 2900km
thick, between 800-3000 Crust, a few km to 70km thick. Lithosphere,
crust and uppermost mantle. Why do tectonic plates move?
Convectional currents are movements of heat within the mantle.
Materials in the mantle is heated by the core, causing the mantle
material to expand, rise and spread out beneath the plates. This
causes the plates to be dragged along and to move away from each
other. Then, the hot mantle material cools slightly and sinks,
pulling the plates along. The sinking mantle material heats up
again as it nears the core and the whole process repeats. The slab
pull force occurs when a denser oceanic plate is forced beneath a
less dense continental plate or oceanic plate in a process called
subduction. As the plate subducts,it pulls the rest of the plate
along. The subducting or sinking plates drives the downward-moving
portion of convection currents. The mantle material which is found
away from where the plates subducts drives the rising portion of
convection currents. Divergent plate boundaries. Oceanic x2,
ridges, such as the mid Atlantic ridge. The magma rises after the
plates move apart, this causes the hot magma to rise. The magma
rises and cools., volcanic islands are formed when the magma builds
up to the sea level, and formes a island. Continental x2, rift
valleys are formed, active volcanoes and earthquakes can be found
along the rift valleys which the continental plates are diverging.
Such as the east African rift valley. Convergent plate boundaries.
Oceanic x2, trenches, such as the Mariana trench. The denser
pacific plate subducts under, it melts and the magma rises and the
Marianna islands are formed. Earthquakes may also occur, causing
tsunamis. Continental x2, fold mountains are formed due to the
pressure. The Himalayas is an example. Between the Indian plate and
the Eurasia plate. Oceanic continental, the denser oceanic subducts
under, forming a trench and fold mountains / volcanoes. This is as
the plate melts and the magma rises. The Australian plate, the
Sunda trench, the barisan mountains and the Eurasian plate.
Transform plate boundaries, north Anatolian fault, fault lines are
formed. Anticline is the highest part or the up part of an fold
mountain and the down fold is called the syncline. Rift valleys and
block mountains. They are formed along fault lines, the tensional
force moves the block mountains apart from the fault line and then
forming rift valleys. Pg23 Volcanoes A magma chamber(where magmas
are stored) , vents(openings on the earth’s surface linked to the
magma chamber), the upward motion of volcanoes are known as
vulcanicity. Magma rises from the magma chamber to the surface and
it is know as lava after that. Lava builds up around the vent,
solidifying to form a small volcanic cone. The bowl shaped opening
is called the crater. When a volcano erupts, lava, ash and rock
fragments are released. The force of the volcanic eruptions depends
on the amount of pressure and gas in the magma. The summit of a
volcano may be blown off during an explosive eruption. The sides of
the crater collapse inwards due to the loss of structural support.
As a result, a large depression known as a caldera is formed. New
eruption of lava covers the ash layer and builds un the volcano.
During the formation of the volcano, the vent may become blocked.
This forces the magma to find a new exit route to the surface. A
secondary cone of newer volcanic material will then develop. The
viscosity refers to the stickiness of the lava or its resistance to
flow, low-silica lava has a lower viscosity which results in less
explosive volcanic eruptions. This type of lava allows gases to
escape easily and flows more easily through the vent before
reaching the surface. As shield volcano are formed by low silica
lava or lava with low viscosity, there is a gentle slope. Strato
volcanoes are formed by high silica lava or lava with high
viscosity, this kind volcano has a higher and steeper volcano.
Secondary vents are also formed when magmas rises out from its
secondary vents. The pacific ring of fire, a ring of “fire” on the
Pacific ocean. Earthquakes: The focus is the point which the
earthquake happened, and the epicenter is the place directly above
the focus on the earth’s surface. For deep focus earthquakes, the
focus is about 70km to 700 km below the earth’s surface. There are
smaller impacts.The shallow focus earthquake occurs in the upper
70km of the earth’s crust. The factors: Population density,The
level of preparedness,Distance form the epicenter,The time of
occurrence , Type of soil,Location of earthquake. As seismograph is
used to record the seismic waves released by an earthquake.
Tsunami, caused by earthquakes, may start off even as just 1m, but
as the water gets shallower, the wave becomes higher. Also, when
the tsunami is about to hit, the water will retreat first.
Earthquake can cause: Disruption of services, Fire, Landslides,
Destruction of properties, Destruction of infrastructure, Loss of
lives Indonesia, 9.2, 228000. Haiti, 7.0, 300,000. Volcanoes,
landslide caused by the collapse of a volcanic cone during a
volcanic eruption. Destruction by volcanic materials. Pollution
Effects of the weather (volcanic winter) Benefits, fertile volcanic
soil, precious stones and minerals; building materials. Tourism and
geothermal energy. Fatalistic approach, accepted as unbelievable
events. Acceptance approach, accepts the risks. Adaptation
approach, well-prepared. Land use regulations, building design,
infrastructure development, emergency drills and use of technology.
Short term responses, tents, medical aid, food,water, calling for
humanitarian aid, searching and rescuing, handling the
status(emergency services etc) Long term, improving infrastructure,
compensating people who lost their land and property, ensuring the
affected region recovers economically, improving health options.
Weather is the condition of the atmosphere at a particular place
and time, the atmosphere is a layer of air surrounding earth. The
weather affects how we live from day to day. The climate is the
average condition of the atmosphere of a specific place over a long
period of time, usually over 30 years. Temperature is the degree of
hotness or coldness of a place. This is determined by the energy
from the sun. High temperature is anything above 20 degrees
celcius, and low temperature is anything below 10 degrees celcius
The surface of teh earth heats up, which in turn heats up the
atmosphere. Mean daily temperature, diurnal(day) temperature range,
mean monthly temperature,mean annual temperature, annual
temperature range. Factors: Latitude: the “concentration” of sun
rays, or the amount of sunrays concentration. A place with latitude
of 0n receives more sunlight concentration than a place with 90n
Altitude: the height in short, above sea level. The higher the
altitude, the colder it is as there are less air concentration and
the air is less dense. Thus, less sunrays are absorbed. Also, the
surface area is significantly smaller. Distance from the sea: the
maritime effect of which is a preserving effect that large water
bodies have on the climate of coastal areas. It causes coastal
areas to have smaller annual temperature range. This is because the
sea cools and heats slower than land. The continental effect is the
effect that continental surfaces have on the climate of in land
areas, it causes the land to have larger annual temperature ranges
than the coastal areas near to the sea. Cloud cover: the clouds
absorb the incoming solar rays and reflect the heat going out,
thus, giving a preserving effect. This mean the more cloud cover
the less day night temperature range. So the diurnal temperature
range is smaller. Relative humidity: the amount of water in the air
right now to the amount of water vapour the air can hold, the
colder it is, the less water vapour the air can hold. Saturation of
which happens at 100% relative humidity causes clouds to be formed
with the help of condensation nuclei and also, the temperature of
which saturation happens is known as dew point. Clouds are formed
mainly due to evaporation of water vapors, which causes saturation
at the dew point and which condensation takes place when there are
tiny particles called the condensation nuclei for the water vapour
to condense on. A cloud is a visible mass of water or ie crystals
that are suspended in the atmosphere. The water droplets may
eventually grow large enough to fall to the earth’s surface as
precipitation. Areas with above 1500 mm are considered having high
rainfall, and areas with below 250 mm are classified as having low
rainfall. Convectional rain occurs when the earth’s surface is
heated intensely, hence, this type of rain is common in the tropics
where a larger amount of sunlight is received. The air heats up by
the surface by the sun rays, and thus, become unstable. The air
rises and expands and as the air rises, its temperature begins to
drop and when it reaches dew point, condensation occurs and clouds
become large and heavy enough, they fall to the ground as rain.
Often associated with lightning and thunder. Last only a short time
and is very intense. Relief rain: only occurs to places with a
mountain(above 600m, which Singapore does not have) close a place
with large amount of water bodies. This is because the warm moist
air rises, cools and forms clouds. The rain falls on the mountain
and when it reaches the leeward side(opposite to the windward side,
which is the side facing the water) it is dry and no rain falls.
Wind, formed by air pressure and of which blows from high pressure
to low pressure. Beaufort scale is used to measure it. Land
breeze:night Sea breeze: day Caused by pressure difference The
southwest monsoon,between June and September. Where it is winter in
Australia and summer in central Asia *insert 1000 word essay here
on monsoons. The north east monsoon, between October and February.
Winter in central Asia and summer in Australia. *insert 1000 word
essay here on monsoons. Equatorial climate: between 10N south and
north of equator, hot, small annual temperature. Monsoon climate:
between 5 and 25 N north and south of the equator. High annual mean
temperature, not as high, about 6c in temperature range. Cool
climate, marine west coast climate: 45 to 60 south and north of the
equator, 4 distinct seasons, ranging between -3 to 22. Range of
about 25. Lower total rainfall, evenly distributed throughout the
year. That’s all -Bill.Cui
