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Cecie Starr
Christine Evers
Lisa Starr
www.cengage.com/biology/starr
Chapter 43
The Biosphere
(Sections 43.1 - 43.4)
Albia Dugger • Miami Dade College
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
Earth’s Tilt and Yearly Rotation
D Spring equinox (March).
Sun’s direct rays fall on
equator; length of day equals
length of night.
A Summer
solstice (June).
Northern
Hemisphere
is most tilted
toward sun;
has its longest
day.
Sun
B Autumn equinox
(September). Sun’s direct rays
fall on equator; length of day
equals length of night.
C Winter
solstice (December).
Northern hemisphere
is most tilted away
from sun; has its
shortest day.
Fig. 43.2, p. 724
Earth’s Tilt and Yearly Rotation
D Spring equinox (March).
Sun’s direct rays fall on
equator; length of day equals
length of night.
A Summer
solstice (June).
Northern
Hemisphere
is most tilted
toward sun;
has its longest
day.
B Autumn equinox
(September). Sun’s direct rays
fall on equator; length of day
equals length of night.
Sun
C Winter
solstice (December).
Northern hemisphere
is most tilted away
from sun; has its
shortest day.
Stepped Art
Fig. 43.2, p. 724
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
Circulation Patterns and Major Winds
Major Winds Near Earth’s Surface
Idealized Pattern of Air Circulation
D At the poles, cold air sinks and
moves toward lower latitudes.
C Air rises again at 60°
north and south, where
air flowing poleward
meets air coming from
the poles.
B As the air flows
toward higher
latitudes, it cools and
loses moisture
as rain. At around
30° north and south
latitude, the air sinks
and flows north and
south along Earth’s
surface.
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.
Cooled, dry
air descends
E Major winds near
Earth’s surface do
not blow directly
easterlies (winds
north and south
from the east)
because of the
westerlies (winds effects of Earth’s
rotation. Winds
from the west)
deflect to the right
of their original
direction in the
northeast
Northern
tradewinds
Hemisphere and
to the left in the
(doldrums)
Southern
Hemisphere.
southeast
tradewinds
westerlies
easterlies
Fig. 43.4, p. 725
Circulation Patterns and Major Winds
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
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Animation: Air Circulation and Climate II
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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
Rain Shadow Effect
Fig. 43.6.1, p. 727
Rain Shadow Effect
A Prevailing winds move
moisture inland from the
Pacific Ocean.
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
3,000/ 85
1,800/ 125 2,000/25
1,000/25
1,000/ 85
15/ 25
Fig. 43.6.1, p. 727
Rain Shadow Effect
Fig. 43.6.2, p. 727
Rain Shadow Effect
Fig. 43.6.3, p. 727
Coastal Breezes
Coastal Breezes
A In afternoon;
the land is warmer
than the sea, so
the breeze blows
onto shore.
cool
air
warm air
Fig. 43.7a, p. 727
Coastal Breezes
B In the evening,
the sea is warmer
than the land; the
breeze blows out
to sea.
Fig. 43.7b, p. 727
Coastal Breezes
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.
Stepped Art
Fig. 43.7, p. 727
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
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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
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
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Animation: Major Biomes
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