hazardous Earth Flashcards
name a primary impact of an earthquake
death/injuries
damaged buildings
damaged roads
name a secondary impact of an earthquake
fires
landslides
disease
tsunamis
what happens at a collision zone
e.g. Himalayas
2 continental plates collide and buckle
what are shield volcanoes?
they are found on constructive plate boundaries or hotspots
they have gently sloping sides and a wide base
they have basaltic magma which is thick with a low silica and gas content.
They erupt frequently, but not violently
what are composite volcanoes?
they are found on destructive plate boundaries and have steep sides and a narrow base
they are made up of layers and ash
they also contain andesitic magma which contains lots of silica and gas
why are composite volcanoes more dangerous
composite volcanoes eruptions involve andesitic magma which contains a lot of silica. This clogs up the volcanic vent, so pressure builds up in the volcano, along with a large amount of gas that makes it explosive
what happens at a divergent plate boundary
e.g. Eurasian and North American plates
rising convection currents pull plates apart e.g. mid-Atlantic ridge
what are the layers of the earth and their properties?
inner core - solid - iron outer core - liquid-iron mantle - liquid asthenosphere crust
why are some countries more vulnerable to cyclones?
physical - low -lying land / coastal areas
social - poor areas
economic - richer countries have better prediction, protection, and evacuation strategies
what are the physical hazards of cyclones?
storm surges
landslides
flooding
high rainfall
what are the impacts of storm surges?
large areas of low pressure allow the sea level to rise and combined with the wind, the water surges towards the land, eroding beaches, and damaging sea defenses
how do landslides affect people and the environment?
soil becomes saturated due to high rainfall and slides injuring people below
why do cyclones dissipate?
- they reach land
- colder temperatures
- winds blow in different directions
what evidence is there for natural climate change?
tree rings= thicker rings indicate warmer, wetter weather
ice cores= indicate levels of CO2 from when the ice formed and settled
historical sources= diaries, paintings, harvest records
what are the human causes of climate change?
industry
energy
transport
agriculture
name some natural causes of climate change
sunspots on the sun are hotter and last between 10-100 years
volcanoes and asteroids cause large amounts of ash and sediment to rise into the atmosphere; blocking the sun and cooling the Earth. These effects last around 1-5 years
what are the Milankovitch cycles?
The shape of the Earths orbit changes every 100000 years affecting the amount of sunlight it receives and can last between 20000-100000 years
how does global and atmospheric circulation affect arid and high rainfall areas?
warm air creates low pressure. Rising air cannot hold as much moisture so precipitation is higher
when cool, dry air descends it creates high pressure therefore there is little precipitation
how do ocean currents redistribute heat around the earth?
cold, salty, dense water sinks
as it sinks warm water from lower altitudes is pulled in
this then travels, cools, and sinks
the cycle repeats
what happens at a conservative plate boundary
e.g. San Andreas fault
2 plates slide past each other
how can you predict a cyclone?
satellites are used to spot a tropical cyclone forming
forecasters can predict its track and storm surge heights
how do tropical cyclones form
1- 26.5C
- high humidity - lots of moisture in the atmosphere
- rapid cooling-rising air must condense quickly to generate power for the cyclone
- low wind shear - if winds are blowing in different directions, the cyclone won’t form
- Coriolis effect-strongest between 5-30 of the equator
- low pressure
how does the atmosphere transfer heat around the earth
global circulation system
warm air rises at the equator
cool air falls
cycle repeats
how do circulation cells redistribute heat around the earth?
warm air rises=low pressure
cool air falls=high pressure
hot air at the equator rises, cools, then travels north and south, where it sinks
the cells meet and energy is transferred
what are ocean currents?
e.g. the Gulf stream
ocean currents transfer heat around the globe
they are powered by:
-wind
- density differences (due to salinity and temperature)
what are the key characteristics of cyclones?
low pressure- warm, moist air rises sucking more air up behind it
rotation - Coriolis helps rising air to spiral and drags in strong winds
structure - a cylinder of rising, spiraling air surrounding an eye of descending, high-pressure air
why do cyclones intensify
temperatures over 26.5C
low wind shear
high humidity
what’s the difference between the crusts
continental crust - less dense - granite
oceanic crust - more dense- basalt
how do convection currents contribute to plate movement
- the core heats the molten rock to create a convection current
- heated rock from the mantle rises
- at the surface the convection currents move the tectonic plates in the crust
- it cools and flows back to the core to be reheated
what happens at a convergent plate boundary
e.g. Nazca and South American plates
2 plates collide and one subducts under the other
what’s the evidence for climate change
in 2015 average temperature was 1C higher than the average temperature in 1800-1900
oceans warm 0.11C per decade
Arctic sea ice covers 13% less of the sea each decade
