Studied by 5 peopleglobal atmospheric circulation 1&2
at the equator the sun warms the earth, which transfers heat to the air above causing it to rise creating a low pressure belt. as the air rises it cools and condenses forming clouds and rain
this cool, dry air moves away from the equator, at 30N/S this air sinks, creating a high pressure belt with cloudless skies and very low rainfall
global atmospheric circulation 3
the cool air reaches the ground surface and moves as surface winds either back to the equator or towards the poles
trade winds
winds blowing towards the equator
they blow from SE in the southern hemisphere and from NE in the northern hemisphere, at the equator these trade winds meet and heat from the sun causes them to rise and form clouds
westerlies
surface winds blowing towards the poles
they blow from NW in the southern hemisphere and SW in the northern hemisphere
global atmospheric circulation 4&5
at 60N/S of the equator the warmer surface winds rise meet cold air from the poles
hadley cell
low pressure
warmer less dense air rises, spreads towards the poles gradually cooling and sinking before descending to the surface and back to the equato
convectional rainfall
warm air rises where it starts to cool and condenses to form clouds
frontal rainfall
2 different air masses meet so warm is pushed up so it cools leading to rainfall
ferell cell
high pressure
heat transported from equator to the poles causing semi permanent areas of high and low pressure
polar cell
low pressure
colder dense air rising in the polar regions flows at 60/70 n/s, leaves polar regions, warms and rises returning to the poles at high levels
why do some parts of the earth recieve more radiation than others?
because of the earths curve, at higher latitudes the solar radiation is spread over a larger SA but near the equator its more concentrated
radiation also must travel through a greater depth of atmosphere at higher latitudes
what does GAC do to heat
redistributes heat, stopping the equator from becoming too hot and the poles becoming too cold
what is a low pressure weather system
where air is rising so theres much more rainfall, resulting in area with lots of rainfall near the equator and wet areas in high/mid latitudes eg uk
what is a high pressure weather system
where air is descending giving clear skies and little rainfall leading to dessert regions
what influence does the spin of the earth have
the different speeds that the earth moves at the equator compared to the poles causes the movement of the air to bend
how does the coriolis force work
as air moves away from the equator it doesnt move in a straight line, it moves in a curved direction due to air flowing from a faster to slower moving region
how does the coriolis force impact winds
winds blow anticlockwise around low pressure and clockwise around high pressure in the northern hemisphere and vice versa in the southern hemisphere
what is the subtropical jet stream
a belt of strong upper-level winds lying above regions of high pressure, it travel in lower latitudes at higher elevations due to the increase in the tropopause at lower latitudes
what is the polar jet stream
between the polar and ferell cells there is a boundary between cold polar air and warm tropical air, the wind is found in the upper part of the troposphere and moves in a westerly direction at mid latitudes
what are the jet streams
strong winds found in the tropopause, powered by a difference in temperature that creates a pressure difference creatingn a force to power the jet stream
how is heat transferred by ocean currents
large scale movements of water than transfer heat energy to from warmer to cooler regions
surface currents are caused by winds and help transfer heat away from the equator
deep ocean currents are driven by water density, when water freezes the surrounding water gets saltier increasing its density, as it gets denser it sinks causing warm water to to flow at the surface creating a current, the warmer water is cooled and sinks continuing the cycle
the earths climate is always changing
the quaternary period, 2.6 million years ago until now
before the quaternary period, the earths climate was warmer and stable
during the quaternary period, global temperature has shifted between cold glacial periods and warmer interglacial periods (that last around 10,000 years)
the last glacial period ended around 15,000 years ago, since then the climate has been warming
ice sheets as evidence for cc
cores can be drilled into ice to measure the amount of co2 in the ice, this is evidence of temperature as levels of co2 tend to be lower in cooler periods
tree rings as evidence of cc
as a tree grows it forms a new ring each year, the rings are thicker in warmer wet conditions, tree ring timescales are produced which are accurate
pollen records as evidence of cc
pollen becomes trapped in ice and sedimentary rocks since certain plants can only grow in certain conditions this gives information of what the climate was like
historical sources as evidence of cc
cave paintings, diaries and documentary evidence, very biased and subjective, not reliable
natural causes of cc-solar variation
suns output isnt constant it changes in cycles of around 11 years, caused by sunspots which are cooler area that are visible as dark patches
they increase the suns energy output
1% change in solar output could make the temp change by 0.5-1c so doesnt explain massive chamges
natural causes of cc- milankovitch cycles
variations in the way the earth moves as it orbits the sun
milankovitch cycles- axial tilt
the earths tilt varies between 21.5-24.5c every 42,000 years, the greater the angle of the tilt the hotter summers, and the colder winters
closer tilt- more solar radiation
milankovitch cyles- precession
the earths spin wobbles over a 21,000 year period due to forces from the sun and the moon, this can cause the N or S hemisphere to receive more/less radiation at different times of the year
milankovitch cyles- eccentricity
shape of the earths orbit varies from nearly circular to nearly elliptical and back again every 96,000 years, glacial periods happen when the orbit is more circular, and warmer periods when its more elliptical
natural causes of cc- volcanic activity (sulfur dioxide)
volcanoes release sulphur dioxide which enters the stratosphere abd forms acid droplets which cause albedo which cools the surface - SHORT TERM - may cool conditions for a couple of months
natural causes of cc- volcanic activity (co2)
traps heat in the atmosphere leading to global warming, lasts in atmosphere for 100 years but only small amounts of co2 released
greenhouse effect
incoming energy from the sun is short wave length radiation, outgoing energy from the earth is long wave length radiation
gasses in the atmosphere naturally act as an insulating layer, letting short wave length radiation in but trapping long wavelength radiation helping to keep the earth the right temperature
enhanced greenhouse effect
too many ghgs in the atmosphere means less heat escapes to space and re radiated heat from the earth is trapped by ghgs warming up the planet
human causes of cc- industry
uses a lot of energy
sometimes releases ghgs into the atmosphere
industrial waste ending up in landfills where it decays releasing methane
human causes of cc- transport
most vehicles run on fossil fuels which release ghgs when burnt
car ownership increasing
human causes of cc- farming
rice paddies and livestock produce a lot of methane
growing population means higher demand for cattle and rice
deforestation leaves more co2 in the atmosphere
affect of cc due to rising sea level
rising sea levels due to glaciers to retreat and ice sheets to melt increases costal erosion and risk of flooding in coastal areas
economic impact - effects trade, big cities where coastal areas contribute to the economy
large scale, social, economic
affect of cc due to warmer temp/drought
more frequent drought negatively effects farming, lower crop yeilds lead to food shortages especially near the equator leading to malnutrition etc.
global impact - globalisation means countries are reliant on each other
social, economic, environmental
affect of cc due to retreating glaciers
glaciers provide water for rivers, as they retreat it may initially cause flooding but eventually cause rives to dry up leading to loss of ecosystems
contributes to rising sea levels
global, long term - effects ocean currents
uks climate
temperature follows a seasonal pattern, ranging from 4-17
precipitation follows a seasonal pattern, ranging from 120mm-70mm per month
sunshine follows a seasonal pattern, ranging from 40 hours- 180 hours per month
uks climate over past 1000 years
0.5 degrees increase in medieval period due to high sunspot activity and more volcanic activity
0.7 degrees decrease in the little ice age due to less sun spot activity and sulfur dioxide from volcanoes
climate in NW of the uk
wettest climate, 100mm rainfall per month
climate in NE of the uk
coldest climate, min temp of 1 degree in winter and max of 12 in summer
climate in SW of the uk
warmest climate, lowest average temp in winter of 5 degrees
climate in SE of the uk
hottest summers, average of 17 degrees in july, least wet regions with 50mm of rainfall per month on average
why does western uk experience more rainfall the east
uk has a south westerly prevailing wind that hits the west coast which has more upland areas
this causes the wind to be pushes up where it cools and condenses and falls as rain
continentality effect on uk climate
uk made up of islands, areas nearer the sea are warmer in winter because the sea stores heat
areas nearer the sea are cooler in summer because the sea takes a long time to heat up so cools the land down
ocean currents effect on uk climate
north atlantic drift and gulf stream bring warmer water from the carribean across the atlantic to the west coast
this keeps the west coast of the uk warmer than other countries on the same latitude
latitude effect on uk climate
50/60N so sun rays have more atmosphere to pass through so arrive at a low angle and are spread over a larger surface area
earths tilt means uk has shorter winter days
explain how GAC distributes heat energy from the equator to the poles? (3)
the sun heats the earth at the equator, warm air rises as it rises it cools and moves away from the equator, the cool air sinks and some is drawn towards the poles as surface winds
explain how ocean currents are created by changes to water density at the poles? (2)
water at the poles freezes and releases salt into the water around it making the water denser, the dense water sinks and the warm water flows to the surface creating a current
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