G1 Geography Resit- Climate

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Climate Definitions

weather- conditions of a specific area/ short time (atmospheric conditions experienced day to day)

climate- long period of time

Latitude- position of locations

Seasons- tilt of the earth

Altitude-height of the location

Continentality- closeness to mountains, oceans etc

Meteorology- study of weather and climate

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Patterns of Climate

The nature of a regions climate is determined by the temperature and precipitation it recieves

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Temperature is dependent on LATITUDE

Temperature depends on the amount of solar energy recieved, which varies spatially and seasonally. It also depends on altutide.

1) TEMP AND LATITUDE:

51% of insolation reaches earth's surface

Low latitudes near the equator are warmer than high latitudes near the poles due to the intensity of sun light (insolation).

Angle of insolation= spread of insolation on the surface, the higher the angle the more intense. Equator is more focussed with lower latitudes being concentrated more.

Amount of atmospheric insolation passes through- insolation decreases as it is absorbed by the reflected gases. Straighter angle= more intense like at equator.

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Temperature is dependent on SEASONS

2) TEMP AND SEASONS:

Earth is tilted at 23 1/2 degrees on its axis

Summer Solstice= 21st June in Northern Hemisphere, 21st December in South

Winter Solstice= REVERSED

Arctic Circle= 24 hrs daylight

Antarctic= 24hrs darkness

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Temperature is dependent on ALTITUDE

Larpse rate change in temperature with altitude

Temperature roughly decreases with height by 1 degree for every 100m above sea level

Higher = less sruface area, less area to absorb insolation// thinner atmosphere so reflected insolation won't be absorbed

Air pressure lower = insolation easier to travel away. This is why TEMPERATURE DECREASES WITH ALTITUDE

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Temperature is dependent on CONTINNTALITY

Oceans have higher specfic heat capactiy- amount of energy need to raise 1g by 1 degree

Ocean temperatures have little variations between seasons

Land masses have low specific heat capacity and herefore temperatures have HIGHER VARIATION between seasons.

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Precipitation...

Mean precipitation is goverened by global atmospheric circulation patterns that create broard bands of high rainfall at the equator and in the termperate regions, and low rainfall at the tropics and poles

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Precipitation is dependent on LATITUDE

High precipitation at mid latitude and equator, low precipitation at tropics and poles

Atmospheric circulation of air leads to the formation of high and low pressure zones;

Low pressure zone- air rises through atmosphere, as it rises it cools, condenses into clouds and rain occurs

High pressure zone- air sinks, through atmosphere, as it sinks it warms and therefore no clouds for precipitation to form

EQUATOR- HIGH PRECIPITATION (low pressure zone)

TROPICS- LOW PRECIPITATION (high pressure zone)

MID LATITUDES- HIGH PRECIPITATION (tropic and polar air meets at a low pressure zone)

POLES- LOW PRECIPITATION (cold air sinks at high pressure zone)

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Precipitation is dependent on ALTITUDE

IF MOIST AIR IS FORCED UPWARDS BY PREVAILING WINDS, AIR WILL COOL AND RAIN CLOUDS WILL CONDENSE AND FORM. THIS OCCURS BECAUSE OF MOUNTAINS/ OBSTACLES, CREATING RAIN SHADOWS ON THE OTHER SIDE!

(Diagram of rain shadow)

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Precipitation is dependent on CONTINENTALITY

In land areas = drier than costal as moisture is required for rain clouds. More moisture as oceans evaportate near coasts

The proximity of the sea keeps temperatures warmer in winter and cooler in summer. Yet keeps land cooler in winter and warmer is sumer.

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Climate and Biomes

The climate of a region will determine the vegetation that is able to grow there. The plant communities that survive naturally in a region form large-scale ecosystems called biomes.

Biome- zonal ecosystem

Biome locations determined by; climate, average temperatures and annual precipitation.

Hot and wet= tropical rainforest

Climatic climax communities- biome determined entirely by climate , like tropical rainforest

Plagioclimax- interfered with by humans, e.g- grasslands in Europe due to agriculture

The continent Africa is split up between a majority of 'dessert and scrub' biome in the north, with more grassland towards central and southern regions.

Similarly, Europe is divided between tundra and ice desert high north, some grasslands towards southern Europes and temperate forest throughout western, central and eastern europe

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Tundra Biome Key Features

DISTRIBUTION:

  • 1/5 of the Earth's surface
  • Found at high altitudes such as; North America, Europe, Russia, North Pole
  • Latitude- Northern Hemisphere 60-70 degrees

CLIMATE/ SEASONS (COLD):

  • High latitudes- extreme seasons
  • Summer is May to August with 24hrs sunlight
  • Winter is November to February with 24hrs darkness
  • No significant Spring or Autumn
  • Low precipitation at 250mm per year (rain, snow, hail, sleet)
  • Summer= 6-10 degrees, Winter = -40 degrees, -57 lowest recorded

SPECIES- low shrubs,sedges, short grasses, falcons, snowy owls, reindeer, rabbits, polar bears, arctic fox, caribou, salmon, cod, trout- ADAPTED TO EXTREMLY COLD ENVIRONMENTS

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Tundra and Climate Change

The tundra is one of the most at risk biomes, it is estimated that by 2100 77% of the tunrda in Alaska will have disappeared as global temperatures rise and ice melts.

This will reuce the availability of foof for native species such as the Caribou.

Polar bears as of 14th May 2008 are an endangered species, borreal forests shift up to 500km worth of North Alaska.

Ice levels have decreased by 14% of 1970 figures.

The world conservation union projects polar bear numbers wil drop by 30% by 2050 due to loss of arcitic sea ice as they have to swim longer and there's less fish to catch

Melting tundra permafrost- usually acts as a carbon sink where reamins of plants are now decomposing, releasing co2 and methane which increase temperatues- CYCLE. Methane emissions from the arctic have risen 31% between 2003 and 2007. Methane is highly flammable in large amounts- and is found this way.

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Long Term Patterns

Glacials- long periods of coldness

Interglacials- long periods of warmer weather

Stadials- short periods of coldness

Interstadials- short periods of warmer weather

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Long Term Patterns

Over 100s of years temperatures fluctuate resulting in warm interstadials and cold glacials. The younger dryas was a cold stadial event that occurred 13,000 years ago. Currently we are in an interstadial called the Holocene. However, over the last 1 million years the earth has been colder resulting in numerous glacial perdiods The last glacial period was the devenisan which occured between 80,000 and 10,000 ybp.

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LONG TERM- MILANKOVITCH CYCLES

Variations in the Earth's orbit which affect the intensity of insolation, follows 3 cycles:

1) ECCENTRICITY CYCLE  'STRETCH'

  • 100,000 YEARS-  CHANGE IN THE DEGREE OF ROUNDNESS OF SPHERE
  • The earth increases distance from the sun as it rotates, resulting in colder glacial periods

2) OBLIQUITY CYCLE 'TILT'

  • 41,000 YEARS
  • The tilt of the earth determines the seasons and level of insolation when it is more tiled the seasons are more extreme- Tilt can vary between 22.1 and 24.5 degrees

3) PRECESSION OF THE EQUINOXES 'WOBBLE'

  • 19,000-23,000 YEARS
  • 'Switches' seasons around and changes the direction you're facing. Northern and Southern hemispheres swap, changing seasons and changing levels of insolation and climate.
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LONG TERM- MILANKOVITCH CYCLES AFFECT

A combination of all 3 makes colder summers and a glacial period.

Present day= mild winter, cooler summers

When solar energy is high, the global ice volume is low. More solar energy means more insolation so ice cannot form.

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LONG TERM- CHANGES TO OCEAN CURRENTS background

Surface winds help transfer surface water from the reopics to the poles. Thermohaline currents carry stored heat from the tropics to the poles. Thermohaline currents carry stored heat from the tropics to the mid-latitudes. These currents are caused by cariations in water density rather than wind.

Surface evaporation from the oceans creates increasingly dense water which will sink to the lower ocean. In other part water rises creating an atmospheric conveyor system.

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LONG TERM- CHANGES TO OCEAN CURRENTS

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Evidence of Long Term Climate Change

GLACIAL LANDFORMS- UK was covered by ice sheets in Devensian period, glacial land forms in highland areas (Snowdonia, Lake District) and deposition of edoded material low down. CWM Idwal (corrie), Ty Fan (pyramidal peak), Gribben Ridge (Arete), Llyn Ogwen (Ribbon Lake) and Llyn Idwal (Corrie lake) and 1000s of scattered erratics are all evidence.

FOSSIL SEDIMENTS- stenotopic fossils to see how biomes have changed coleopetera beetles have over 30,00 species and have colonised to most biomes, parts of them presetve as fossils. They are mobile, shift distribution according to cliimate and have limited evluntionary change. Can be seen at St Bees Head has many beetle fossils.

OCEAN DEPOSITS- during integlacial periods there's more of a blance of O16 and O18 as lighter O16 evaportates but is then returned as rain. However, in glacial periods the O16 can't return and is stored as ice on land. During interglacials ice melts and isotope can return.

Deep sea sediments make shells from water (planktonic foraminifera) which is used to analyse oxygen levels and see climatic changes

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SHORT TERM- SUNSPOTS

Sunspots are intense areas of insolation which occur in 11 year cylces, they appear darker.

Short term climate can be changed when sunspot energy is reduced, this can be seen in the Little Ice Age occuring 1607-1804 , where global temperature reduced around 0.4-0.8 degrees. This reduction in sunspots reduced insolation levels by 0.25 degrees, enough for cooling. Evidence can be seen in the form of frost fairs on the Thames, London, colonies in Greenland starving due to crop failures and glaciers seen within places such as the Alps started to advance. As sunspots returned, the tempearature increased again as the level of insolation did.

Volcanic activity and an increase in reflective albido can also alter short term climate change and are suggested to have impacted the Little Ice Age event.

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SHORT TERM- BEFORE EL NINO

BEFORE:

Trade winds transfer warm waters to the equator and west which then heat up the air above causing convectional uplift, air rises.

At the east air returns and sinks, upwelling of cold water from under the thermocline occurs to replace warm upper layer.

West- low pressure zone, high precipitation

East- high pressure zone, low precipitation

The pressure of trade winds results in Australiasia being 50cm higher sea levels and 8 degrees warmer than peru.

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SHORT TERM- DURING EL NINO

El Nino occurs every 3-4 years and every 30 years for extreme events

During El Nino trade winds are weaker, non existent or reversed. This reverses the convection loop and causes reversed climates with the west being dry and the east being wet as now air sinks in the west and rises in the east.

Water moves back towards the east, with the Peruvian sea levels rising by 30cm and conditions across the Pacific Ocean are calmer. This distrots the paths of jet streams, causing teleconnections around the world and disruption to weather patterns.

1997/98:

PAPUA NEW GUINEA (and Indonesia)- extreme drought with forest fires, 80,000 at risk of famine, poor farming conditions and aid reliancy

PERU- extreme flooding; flash floods, 6 years of rain in 12 days, $700bn in damage, 3 flood direct deaths and 292 deaths following aftermath such as cholera and other related illnesses.

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SHORT TERM- LA NINA

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Evidence for Short Term Climate Change

HISTORICAL RECORDS- daily weather records since 1869 in UK, temperatures increased 0.7 degrees during last 100 years. Atmostpheric CO2 records from Mauna Lou in Hawaiian Islands sine 1957 alongside crop yields, art work etc

RETREAT OF GLACIERS- ice bodies at high altitudes which are controlled by mass balance. If outputs are greater then ice decays. In the past 125 years the Athabasca Glacier has retreard by more than 1.5km, tracked by sign posts. Greenland- in 1996 lost 96km2 in 2014 lost 375km2 (global warming)

SEA LEVEL CHANGE- melt water from glaciers can cause mean sea level to rise. This ads to the affects of thermal expansion which leads to higher sea levels. 2011 nitergovernmental panel on climate change projected the meansea level to rise by an estimate of 59cm by 2100. Since 1992 sea levels have risen 110mm.

PHENOLOGY- butterflies at Wyre Forest Worcestershire- ermering earlier- speckled wood and orange tip emerged in May in 1971 and in 2005 began to emerge in April.

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HUMAN CAUSES- 'GREEN HOUSE EFFECT'

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HUMAN CAUSES- 'ENHANCED GREEN HOUSE EFFECT'

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HUMAN CAUSES- CO2

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HUMAN CAUSES- METHANE

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HUMAN CAUSES- NITROUS OXIDE

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HUMAN CAUSES- WATER VAPOUR AND CHLOROFLUOROCARBONS

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HUMAN CAUSES- EVIDENCE FOR GLOBAL WARMING

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