2.6 - climate, biomes, tricellular model, El Nino La Nina, cyclones

weather

state of the atmosphere at any particular moment in time

climate

the average and extreme states of the atmosphere over a period of time no less than 30 years

• temperature

• rainfall

• winds

• humidity

• cloud cover

• pressure

climate graphs

used to illustrate the average temperatures and rainfall experienced at a particular place over a year

biomes

collections of ecosystems sharing similar climatic conditions

• have distinctive abiotic factors and species

*all Earth’s biomes make up the biosphere

biome distribution Whittakar 1975

• ecosystems developed in similar conditions in different parts of the world can have many simmilar features

major influences on distribution of terrestial biomes:

• precipitation

• temperature

• insolation (exposure to sun)

biomes types

forrest biomes

• tropical rainforest

• temperate forest

• boreal forest

grassland biomes

• savannas

• temperate grasslands

desert biomes

• hot desert

• cold desert

• coastal desert

tundra biomes

• arctic tundra

• alpine tundra

features of tropical rainforest

(0 < x < 24)

• eg. Amazon

• high precipitation

• temperature

  • 26 < x < 28

• no seasons

• high biodiversity

features of savannas

(5 < x < 30)

• eg. Africa

• low precipitation

• temperature

  • 15 < x < 35

• wet and dry seasons

• wide range of biodiversity

features of hot desert

(15 < x < 30)

• eg. Australia

• extremely low precipitation

• temperature

  • day: 25 < x < 50

  • night: 0

• summer and winter seasons

• low biodiversity

features of temperate grasslands

(40 < x < 60)

• eg. Africa

• very low precipitation

• temperature

  • - 20 < x < 30

• 4 seasons

• large biodiversity

features of temperate forest

(40 < x < 60)

• eg. Europe

• medium precipitation

• temperature

  • summer: x > 20

  • winter: -10 < x < 4

• 4 seasons

• wide biodiversity

features of boreal forest

(50 < x < 60)

• eg. Russia

• low precipitation

• temperature

  • summer: x > 20

  • winter: -30

• winter and summer seasons

• low biodiversity

features of tundra

(60 < x < 90)

• eg. Antarctica and North of Arctic circle

• very low precipitation

• temperature

  • - 70 < x < 0

• winter and summer seasons

• low biodiversity

effect of global warming on biomes

shifting of biomes

• range shifts

  • when species move to new areas to find suitable conditions

• biome type changes

  • transition of biome into different type

*due to global warming the warmer biomes, closer to equator, expand and closer biomes contract

impacts of biome shift

• increased competition, predation and disease due to migration

• decline or extinction of species

• impact on:

  • water regulation

  • nutrient cycling

  • carbon sequestation

factors affecting biome distribution

• solar energy

• air pressure

• wind

• atmospheric circulation (tricellular model)

• altitude

• latitude

solar energy functions

• responsible for waether and climate

• amount of solar energy varies with latitude, altitude and distance from the sea

• due to Earth’s curve the radiation is spread over a wider surface at the poles and smaller at the equator

atmospheric pressure function

• distance from surface decreases pressure

• changes in temperature

wind function

• results from differences in air pressure

• wind is generated when air moves from high (cold) to low (warm) pressure

the tricellular model

model of atmospheric circulation

• Hadey cell

• Ferrel cell

• Polar cell

• warmest air at equator

• coldest air at the poles

influence on biomes of the tricellular model

distribution of precipitation and temperature:

• low- latitudes

  • high rainfall

  • high temperatures

  • tropical biomes

• mit-latitudes

  • variable due to interactions between warm and cold air

• high-latitudes

  • low temperatures

  • low rainfall

  • polar desert and tundra exist

ocean currents

• the ocean absorb radiation and ocean current distribute the resulting heart worldwide

• differ according to depth and direction of water movement

Gulf stream

ocean current originating in the Gulf of Mexico, flowing up the East Coast of the United States before moving across the Atlantic Ocean

cold California current

an ocean current that flows southward along the coast of California, bringing cooler temperatures and influencing coastal climates.

impacts of currents on climate and ecosystems

• redistribution of heat helps regulate global climate as it moderates temperature extremes

• affect patterns of ocean productivity, distribution of species and levels of marine biodiversity

trade winds

permanent winds that blow from east to west in the tropics

• caused by strong evaporation and warming in the atmosphere aroun equator

oscillation cycles

fluctuations in wind and seas surface temperatures that influence weather patterns and marine ecosystems.

• El Nino → a warming phase

• La Nina → a cooling phase

*they are irregular and difficult to predict in terms of frequency and intensity

El Nino phase

• east to west winds weaken or reverse

• warmer-than-usual sea surface temperatures

  • central and eastern tropical Pacific

• reduced upwelling

  • decreased marine productivity

  • negative impact on local (Peru and Equador) fisheries and food chains

La Nina phase

• east to west winds strenghten

• strong winds push warm water even further west

• cooler water dominates eastern and central Pacific

  • increased upwelling in South America

    • incresed productivity

climatic effects of the oscillation cycles

El Nino

• droughts and wildfires

  • Australia

  • Southeast Asia

• heavy rainfall and flooding

  • west coast North America

  • west coast South America.

• lower monsoon rains

  • India

  • Southwestern Asia

La Nina

• heavy rainfall and flooding

  • Australia

  • Southeast Asia

• droughts and wildfires

  • Southwest North America

  • South America

• harsher winters

  • Canada

impacts of oscillation cycles on marine ecosystems and economy

El Nino

• lack of nutrient rich water upwelling

  • decline in plankton

    • fewer fish

• warm waters cause colar bleaching

• crops damaged due droughs

La Nina

• promotes nutrient upwelling

  • boosted marine life

    • improved fisheries

• crops damaged due floodings

both

• can increase spread of disease

• can cause economic losses from natural disasters

upwelling

displaced warm surface waters are replaced by cold, nutrient-rich waters that well-up from below

• encourages sea weed growth and phytoplankton blooms

tropical cyclones

rapidly circulating systems with low-pressure centre that originates in the tropic

-strong winds

-heavy rainfall

-wind speed over 119km/h

• hurricanes

  • Atlantic or eastern Pacific Ocean

• typhoons

  • northwestern Pacific Ocean

• cyclones

  • south Pacific and Indian Ocean

how they form

• warm water evaporates

• it condenses into clouds and rain releasing huge amounts of heat energy

• the release of energy warms surrounding air which rises further

• this lowers pressure at the centre

• this pulls in more warm, moist air

• cycle continues and intensifies

• it rotates due to coriolis effect

impact of climate change on tropical cyclones

• ocean warming

  • more evaporation, stronger storms

  • higher sea surface temperatures, bigger intensity of the cyclones

  • rising sea levels due to global warming