© Babak, Steve

Chapter 6Chapter 6::Climate and Terrestrial Climate and Terrestrial BiodiversityBiodiversity

© Babak, steve

Weather & ClimateWeather & Climate Differences between weather and

climate: weather: short–term atmospheric conditions

that include: temperature, pressure, humidity, precipitation, solar radiation, cloud cover, wind direction and speed.

troposphere: the inner layer where weather occurs; contains the air we breathe.

climate: long–term weather of a region. global temperature and precipitation

patterns are determined by uneven heating of Earth by Sun and lead to distinct climate zones according to latitude.

Weather & Climate Con’t.Weather & Climate Con’t.

Fig. 7–2

Global PatternsGlobal Patterns major factors influencing climate:

incoming solar radiation patterns: leads to uneven heating of troposphere from beneath;

air circulation patterns: determined by uneven heating of Earth's surface seasonal changes due to Earth's tilt on axis and

revolution about the sun Earth's rotation on its axis

ocean currents influenced by factors that influence air circulation

plus differences in water density.

Fig. 7–3

Geometry of the Earth & SunGeometry of the Earth & Sun

Earth's rotation (24-hr period), tilted axis (23.5º), and revolution about the sun (365¼ day period) play a major role in weather and climate.

Fig. 7–5

Convection CurrentsConvection Currents Convection

currents: currents in the air or water that are caused by temperature differences.

Warm air rises while cooler air falls.

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Fig. 7–9

Greenhouse EffectGreenhouse Effect

The greenhouse effect is a natural process in which gases (CO2, H2O, methane, etc.) trap heat in the troposphere. Without the greenhouse effect, Earth would be cold and lifeless.

Humans activities are increasing the levels of these gases increase in global temperature.

© Brooks/Cole Publishing Company / ITP

Fig. 7–4

Air Circulation PatternsAir Circulation Patterns

Prevailing winds include westerlies at temperate latitudes, trade winds in the subtropics, & doldrums (stiller air) along the equator.

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Air Circulation PatternsAir Circulation Patterns

Major patterns: air circulation is driven by solar energy

Coriolis effect: a deflection effect occurs as the Earth rotates, resulting in a deflection of air masses to the right in N hemisphere & the left in S hemisphere

Low & high air pressure: low pressure: warm and low density. Leads to high

rainfall as air rises. high pressure: cool and dense air. Results in deserts as

dry air descends

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Ocean CurrentsOcean Currents

Major Patterns: Large circular patterns of water movement

in ocean basins resulting from the Coriolis effect.

Deep currents driven by cooling and increased salinity – both make water denser and cause it to sink.

Currents redistribute heat and influence climate and vegetation.

Currents help in the cycling and distribution of nutrients and d.o. for aquatic life.

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Fig. 7–7

UpwellingUpwelling The

replacement of outgoing surface water with deep, cold, nutrient–rich bottom waters.

Leads to increased primary productivity, with large populations of phytoplankton, zooplankton, fish, and fish–eating birds.

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El Niño–Southern Oscillation (ENSO) Periodic shift (3-4 years) where westerly

winds in the Pacific Ocean weaken or reverse direction, surface water along N and S America becomes warmer.

Normal upwellings stop and reduction in primary productivity.

Strong ENSO affects over two–thirds of the globe.

El Niño–Southern Oscillation (ENSO)El Niño–Southern Oscillation (ENSO)

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Fig. 7–8

TopographyTopography

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Topography, water bodies and other local features create local climate conditions known as microclimate. For example mountains commonly result in high rainfall on the windward side and low rainfall in the rain shadow of the leeward side.

Fig. 7–10

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BiomesBiomes Biome: the major types of terrestrial

ecosystems determined primarily by climate (prec. &

temp.) major biomes:

tundra - tropical rain forest desert - mountains chaparral - tropical dry forest boreal forest (taiga) - tropical savanna temperate grassland temperate deciduous forest

Climate influences the types of plants and animals found in each biome.

Earth’s Major BiomesEarth’s Major Biomes

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Fig. 7–11

Desert BiomesDesert Biomes

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Fig. 7–14

Climate graphs (Climatograms) show typical variation in annual temperature and precipitation for tropical, temperate and polar deserts.

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Desert Biomes Characteristics:

typically < 25 cm (10 in) annual precipitation; sparse, widely spaced, mostly low vegetation cover 30% of land surface, especially at 30° N

and 30° S latitude largest deserts on interiors of continents plants either are typically deep rooted shrubs

with small leaves, succulents, or short–lived species that flourish after rain

animals are typically nocturnal and have physical adaptations for conserving water and dealing with heat.

DesertsDeserts

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Fig. 7–15

                                                                        

            

Grassland, Tundra and Chaparral BiomesGrassland, Tundra and Chaparral Biomes

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Fig. 7–17

Climatograms showing typical variations in annual temperature and precipitation in tropical, temperate and polar grasslands.

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Grassland BiomesGrassland Biomes Characteristics:

sufficient rainfall to support grass, but often too dry for forests

mostly found on interiors of continents maintained by seasonal drought, grazing and

periodic fires that prevent invasion by shrubs and trees

plants include high diversity of grasses and herbaceous plants that typically have broad distributions and that have resistance to drought, grazing and fire

animals include large and small herbivores, along with predators adapted to feed on these herbivores.

GrasslandsGrasslands

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Figs. 7–19 & 7–20

Forest BiomesForest Biomes

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Fig. 7–22

Climatograms showing typical variations in annual temperature and precipitation in tropical, temperate and polar forests.

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See Figs 7–24, 7–25, & 7–26

Forest BiomesForest Biomes Characteristics:

sufficient rainfall to support growth of trees; three types:

tropical, typically broadleaf evergreen trees with high diversity

temperate, typically deciduous broadleaf tree with moderate diversity;

boreal, typically conifers (needle leaves) with low diversity.

community of plants and animals typically distributed in various layers:

understory of herbaceous plants and shrubs; subcanopy of tree saplings; canopy of full–grown trees.

ForestsForests

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Fig. 7–23

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Mountain BiomesMountain Biomes Characteristics:

diversity of habitat because of diversity of altitude, slope orientation, corresponding microclimate and soil over short distances

correspondingly complex patterning of vegetation make up 20% of Earth's surface each 100 m (300 ft) gain in elevation mountain regions contain majority of world's forests; timberline: elevation above which trees do not grow; snowline: elevation above which there is permanent

snow important as watersheds for lowlands.

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Perspectives on Geographical Perspectives on Geographical EcologyEcology

Things to remember: everything is connected; temperature and precipitation

patterns result from interplay of incoming solar radiation and Earth's rotation

temperature and precipitation are major determinants of the distribution of organisms