hazardous earth Flashcards
made by Kate
climate
the average weather conditions of an area occurring over many years
ocean current
redistribute heat around the earth. The heat near the equator is hotter than near the poles. Water moves from hot to cold areas, helped by the movement of the wind across the ocean. A locations proximity (closeness) to water can have a large effect on its climate as water can hold heat for long time.
solar radiation
the earth receives all of its heat from solar radiation from the sun. The solar radiation passes through the atmosphere and heats the ground directly.
high pressure
Air in our upper atmosphere cools, becomes denser and sinks towards the earth. There is a lot of pressure (force) on the ground.
low pressure
as the ground heats up, it warms the air above it, so warm air rises and transfers heat to the atmosphere. Therefore, taking pressure (force) away from the ground.
circulation cells
Hadley, Ferrell and polar cells. They transfer energy from high to low pressure around the atmosphere.
coriolis effect
Winds are caused when the air moves from a high (air sinks) to low (air rises)
pressure. As the Earth rotates, the air does not flow in a straight line, so
winds are deflected away from the equator and flow in a curved path called
the Coriolis Effect.
In the Northern Hemisphere they spin counter clockwise, in the Southern
Hemisphere they spin clockwise.
Inter-Tropical
Convergence zone
A belt of low pressure around the Earth just north and south of the Equator,
where warm, moist trade winds come together.
quaternary period
the last 2.6 million years.
Greenhouse
Effect
A natural process which keeps the Earth warm. Greenhouse gases in the
atmosphere, such as carbon dioxide, trap some of the heat that is radiated
from the surface which would otherwise have been lost into space.
enhanced greenhouse effect
Human activity has increased the amount of greenhouse gases being
released into the atmosphere. This means the Earth absorbs more solar
radiation and as a result is becoming warmer, the greenhouse effect is
intensified.
eccentricity
the orbit of the earth around the sun changed approximately every 100,000 years. from circular to elliptical.
obliquity
as called axial tilt - the earth’s axis changes its angle that it sits at over a 40,000 year period. The angle can range from 22.5 degrees to 24.5 degrees. It is currently at 23 degrees. This tilt creates seasons. When earth is tilted further away from the sun, there are greater variations between seasons, or nearer to the sun making the differences in season less obvious.
Milankovitch
Cycles
also known as orbital forcing. serbian astronomer came up with three natural causes of climate change: obliquity, precession and eccentricity
precession
As the earth rotates on its axis, it doesn’t rotate perfectly. It tends to ‘wobble’ and the direction the axis facing changes. This happens every 24,000 years. This affects seasons.
solar output theory
magnetic storms on the surface of the sun. These create more energy and therefore increase the sun’s heat output by 1%. More spots mean the solar solar radiation received by the earth will be increased, making it hotter.
eruption theory
Large-scale volcanic eruptions can eject huge volumes of ash and dust into
the atmosphere. Some eruptions produce so much that the volcanic material
partially blocks out solar radiation, reducing global temperatures and causing
cooler periods. Long term the increased gases in the atmosphere could have
a potential warming effect as they contribute to the Greenhouse Effect.
historical sources
historical documents such as diaries, paintings and farming records, to examine more recent historical climates.
ice cores
Over hundreds of thousands of years snow falls and gets compacted it
creates layers of ice, such as the ice sheets in Greenland and Antarctica. As
the ice forms it traps air bubbles, which contains a sample of the atmosphere
at the time it was frozen (oxygen and carbon dioxide). The more carbon
dioxide present the warmer, the more oxygen the colder.
tree rings
as trees grow they produce growth rings. These are wider in warmer and wetter regions and narrower in cold and dry climates. These can indicate what the climate was like for 100-1000 years.
thermal expansion
the increase in volume created when a fluid is heated and expands. leading to sea levels rise
tropical cyclone
Tropical cyclones are powered by heat energy that is released as warm air
condenses. They need warm water to form, they also need the Coriolis effect
for them to rotate so they cannot be located at the Equator. They are found
50 to 300 north and south of the equator. A light wind shear then pushes
them over oceans until they dissipate (weaken) on land or colder waters.
Saffir- Simpson
Scale
The scale used to classify tropical cyclones, this is based on the wind speed generated by the cyclone and estimates the damage.
storm surges
an increase in the height of the sea due to a storm. An uplift of water inside the track of the storm over the ocean.
crust
the thinnest layer of the earth. there are two types - oceanic and continental crust
mantle
this is the thickest layer of the earth - nearly 2900 km. its temperature ranges from 1000 degrees near the crust and 3700 degrees near the core. The mantle becomes hotter and denser with depth.
core
This is the centre of the Earth. It is very hot and dense. It has two layers. The
outer core is made of liquid iron and nickel the temperature is between
4500-55000C The inner core is up to 60000C. It is a dense solid ball of iron
and nickel. It cannot melt due to the pressure.
convection currents
Convection currents in the mantle mean the tectonic plates are continuously
moving. Rock heated in the lower mantle due to radioactive decay in the
core, it becomes less dense and rises slowly towards the crust. As it rises, it
cools and becomes more dense. When it reaches the asthenosphere it is
forced sideways as it is blocked by the lithosphere above. It then sinks slowly
towards the core and is forced sideways due to the dense iron and nickel.
asthenosphere
a denser, mobile layer in the upper mantle, 100-300 km deep. Temperatures are high and the pressure, while still high are low enough that rocks can still move.
lithosphere
includes the crust and the top layer of the upper mantle which is made up of peridotite. it is 80-100 km thick, although it is thinner under the oceans and in the volcanically active continental areas. It is broken up into tectonic plates of varying sizes which move on the asthenoshpere
divergent plate boundary
Plates to move away from each other. This mainly occurs under the oceans.
As the plates break apart, rising heat and a reduction in pressure causes the
asthenosphere to melt, forming magma. The magma rises to fill the rift valley
between the two plates creating oceanic lithosphere. Associated features -
Shield volcanoes, mid-ocean ridges and earthquakes. Example - Iceland—
Eurasian plate and North American plate.
convergent subduction boundary
Plates to move towards each other. The oceanic plate subducts beneath the
continental plate as it is denser. As it subducts the increase in temperature
due to friction and pressure force the crust into the asthenosphere which
begins to melt. This creates magma. Associated Features – volcanoes and
earthquakes. Examples - Peru-Chile Trench, Andes Mountains. Involving the
Nazca Plate and South American Plate
Convergent collision boundary
Plates to move towards each other. As the plates are the same there is no
subduction, the collision causes the boundaries to crumple forming fold
mountains. Features - No volcanic activity but there are earthquakes.
Example - Himalayas, Tibetan Plateau
conservative boundary
Plates to slide past each other. The plates can move in opposite directions or
in the same direction at different speeds. Tension and pressure builds
between the plates until one plate jerks and causes an earthquake. Example -
San-Andreas fault, California, USA—North American plate and the Pacific
Plate.
shield volcano
Formed along divergent boundaries and over hotspots. They are gently
sloping domes with a wide base. Basaltic lava is erupted. It has a low silica
content so it is less viscous (sticky) meaning it is runny and flows long
distances before cooling. Eruptions are frequent but gentle.
composite volcanoes
Formed along convergent plate boundaries. They are steep sided, tall and
conical shaped with a narrow base. Made of alternate layers of ash and lava.
Andesitic lava is erupted which has a high silica content making it more
viscous (sticky) so it flows slowly and travels short distances. Eruptions tend
to be infrequent but violent, as the vent becomes blocked with lava so
pressure builds up. Lava bombs and pyroclastic flows and lahars also are
created in the eruption.
earthquake
earthquakes are intense vibrations within the earth’s crust that make the ground shake. They are sudden events. The point of rupture is called the
focus. Seismic waves radiate out from this point. The epicentre is the point
on the ground surface directly above the focus. Earthquakes also occur along
conservative and divergent plate boundaries. Measure using seismometers
and measured on the Richter scale.
