Chapter 43 The Biosphere (Sections 43.1 - 43.4)

Albia Dugger • Miami Dade College

Cecie StarrChristine EversLisa Starr

www.cengage.com/biology/starr

Chapter 43The Biosphere

(Sections 43.1 - 43.4)

43.1 Effects of El Niño

• El Niño is a recurring event in which equatorial waters of the eastern-central Pacific warm above their average temperature

• During an El Niño, marine currents interact with the atmosphere to influence weather patterns worldwide – causing floods, droughts, and fires

• Marine food webs along eastern Pacific coasts decline as warm water flow cuts off nutrient supplies to marine primary producers – in 1998, Galapagos sea lions starved to death

Effects on the Biosphere

• The opposite of El Niño is La Niña, in which eastern Pacific waters become cooler than average – the west coast of the United States gets little rainfall and the likelihood of hurricanes in the Atlantic increases

• El Niño/La Niña events are some of the factors that influence properties of the biosphere, which includes all places where we find life on Earth

Key Terms

• El Niño • Periodic warming of equatorial Pacific waters and the

associated shifts in global weather patterns

• La Niña • Periodic cooling of equatorial Pacific waters and the

associated shifts in global weather patterns

• biosphere • All regions of Earth where organisms live

The Biosphere

• Interactions among Earth’s oceans and atmosphere give rise to El Niño and other climate patterns

Effects of El Niño

Animation: Normal vs. El Niño Conditions

43.2 Air Circulation Patterns

• Climate refers to average weather conditions (cloud cover, temperature, humidity, wind speed) over time

• Regional climates are influenced by factors that affect winds and ocean currents (intensity of sunlight, distribution of land masses and seas, and elevation)

• climate • Average weather conditions in a region over a long time

period

Seasonal Effects

• Seasonal changes in day length and temperature occur because Earth’s axis is tilted about 23 degrees: • In June, the Northern Hemisphere is tilted toward the sun,

receives more intense sunlight, and has longer days than the Southern Hemisphere

• In December, the Southern Hemisphere tilts sunward

• In each hemisphere, the degree of seasonal change in day length increases with latitude

Earth’s Tilt and Yearly Rotation

Fig. 43.2, p. 724

A Summer solstice (June). Northern Hemisphere is most tilted toward sun; has its longest day.

Sun

C Winter solstice (December). Northern hemisphere is most tilted away from sun; has its shortest day.

D Spring equinox (March). Sun’s direct rays fall on equator; length of day equals length of night.

B Autumn equinox (September). Sun’s direct rays fall on equator; length of day equals length of night.


Fig. 43.2, p. 724

A Summer solstice (June). Northern Hemisphere is most tilted toward sun; has its longest day.

Sun

C Winter solstice (December). Northern hemisphere is most tilted away from sun; has its shortest day.

D Spring equinox (March). Sun’s direct rays fall on equator; length of day equals length of night.

B Autumn equinox (September). Sun’s direct rays fall on equator; length of day equals length of night.

Stepped Art


Animation: Orbit Around the Sun

Air Circulation and Rainfall

• Equatorial regions get more sun energy than higher latitudes• At high latitudes, sunlight is absorbed or reflected by more

atmosphere, so less energy reaches the ground• Energy in an incoming parcel of sunlight is spread out over

a larger surface area at higher latitudes

• Variations in energy from sunlight causes surface warming, which drives global air circulation and rainfall patterns

Variation in Intensity of Solar Energy

Circulation and Rainfall (cont.)

• Two important properties of air:• As air warms, it becomes less dense and rises• Warm air can hold more water than cooler air

• Global air circulation and rainfall patterns:• At the equator, warm moist air rises and flows north and

south, releasing rain that supports tropical rain forests• At 30° north or south, dry cool air sinks over deserts • At 60°, warm moist air rises again; then cool air sinks at

the poles

Surface Wind Patterns

• Air masses are not attached to Earth’s surface – the Earth spins beneath them, moving faster at the equator and slower at the poles

• As a result, major winds seem to curve toward the right in the Northern Hemisphere; and toward the left in the Southern Hemisphere

• The prevailing winds in the United States are westerlies

Circulation Patterns and Major Winds

Fig. 43.4, p. 725

westerlies

E Major winds near Earth’s surface do not blow directly north and south because of the effects of Earth’s rotation. Winds deflect to the right of their original direction in the Northern Hemisphere and to the left in the Southern Hemisphere.

A Warmed by energy from the sun, air at the equator picks up moisture and rises. It reaches a high altitude, and spreads north and south.

B As the air flows toward higher latitudes, it cools and loses moistureas rain. At around 30° north and south latitude, the air sinks and flows north and south along Earth’s surface.

C Air rises again at 60° north and south, where air flowing poleward meets air coming from the poles.

D At the poles, cold air sinks and moves toward lower latitudes.

Cooled, dry air descends

easterlies (winds from the east)

westerlies (winds from the west)

northeast tradewinds

(doldrums)

southeast tradewinds

easterlies

Major Winds Near Earth’s SurfaceIdealized Pattern of Air Circulation


Fig. 43.4, p. 725


Animation: Global Air Circulation Patterns

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Key Concepts

• Air Circulation Patterns• Air circulation starts with latitudinal differences in energy

inputs from the sun • Movement of air from the equator toward poles is affected

by Earth’s rotation and gives rise to major surface winds and latitudinal patterns in rainfall

Animation: Air Circulation and Climate I



Animation: Air Circulation and Climate II



43.3 Ocean, Landforms, and Climates

• The ocean is a continuous body of water that covers more than 71% of Earth’s surface

• Its water moves in currents that distribute nutrients through marine ecosystems

• Warm and cold surface currents affect coastal climates

Ocean Currents

• As in air, sunlight affects ocean temperature and sets major currents moving away from the equator

• The direction of surface currents is determined by the force of major winds, Earth’s rotation, and topography• Clockwise in the Northern Hemisphere• Counterclockwise in the Southern Hemisphere

• Deep, narrow currents flow away from the equator along the eastern coast of continents; shallow, wide currents flow toward the equator on western coasts

Climate and Major Surface Currents

Regional Effects

• Mountains, valleys, and other land features affect climate

• High mountain ranges (such as the Rockies) that parallel the coast block moist air from moving inland, causing a rain shadow on their leeward side

• rain shadow • Dry region downwind of a coastal mountain range

Rain Shadow Effect

Fig. 43.6.1, p. 727

Rain Shadow Effect

Fig. 43.6.1, p. 727

A Prevailing winds move moisture inland from the Pacific Ocean.

3,000/ 851,800/ 125

15/ 251,000/ 85

2,000/251,000/25

C Rain shadow on side facing away from the prevailing winds makes arid conditions.

B Clouds pile up and rain forms on side of mountain range facing prevailing winds. moist habitats

moist habitats

4,000/ 75

Rain Shadow Effect

Fig. 43.6.2, p. 727

Rain Shadow Effect

Fig. 43.6.3, p. 727

Rain Shadow Effect

Coastal Breezes

Fig. 43.7a, p. 727

A In afternoon; the land is warmer than the sea, so the breeze blows onto shore.

cool air

warm air

Coastal Breezes

Fig. 43.7b, p. 727

B In the evening, the sea is warmer than the land; the breeze blows out to sea.

Coastal Breezes

Fig. 43.7, p. 727

Stepped Art

A In afternoon; the land is warmer than the sea, so the breeze blows onto shore.

cool air

warm air

B In the evening, the sea is warmer than the land; the breeze blows out to sea.

Coastal Breezes

Monsoons

• Differential heating of water and land also causes monsoons

• Example: In the summer, hot air rises over Asia, drawing in moist air from the Indian Ocean; in the winter, cool air sinks and a dry wind blows toward the coast

• monsoon • Wind that reverses direction seasonally

Key Concepts

• Ocean Circulation Patterns• Heating of the tropics also sets ocean waters in motion• As water circulates, it carries and releases heat, and so

affects the climate on land• Interactions between oceans, air, and land affect coastal

climates

Animation: Major Climate Zones and Ocean Currents



43.4 Biomes

• Biomes are communities with similar climates and vegetation that evolve in widely separated regions as a result of similar environmental factors

• biome • Discontinuous region characterized by its climate and

dominant vegetation

Differences Between Biomes

• Rainfall and temperature are the main determinants of the type of biome in a given region

• Soils also influence biome distribution• Properties of soils vary depending on the types,

proportions, and compaction of mineral particles and varying amounts of humus

• Climate and soils affect primary production, so primary production varies among biomes

Major Biomes and Marine Ecoregions

Primary Productivity

Similarities Within a Biome

• Unrelated species in widely separated parts of a biome may have similar body structures that arose by morphological convergence

• Example: Cactuses with water-storing stems live in North American deserts, and euphorbs with water-storing stems live in African deserts, but cactuses and euphorbs do not share a common ancestor with a water-storing stem

Animation: Rain Shadow Effect



Animation: Major Biomes



Chapter 43 The Biosphere (Sections 43.1 - 43.4)

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