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The Biosphere
Chapter 48
Impacts, Issues
Surfers, Seals, and the Sea
 Giant waves and starving sea lions were two
results of the 1997-1998 El Niño event that
affected climates around the world
The Biosphere
 The biosphere includes all places where we find
life on Earth
• Hydrosphere (ocean, ice caps, and all other
bodies of water)
• Lithosphere (Rocks, soils, and sediments)
• Lower portions of the atmosphere
48.1 Global Air Circulation Patterns
 Climate
• Average weather conditions – such as cloud
cover, temperature, and humidity – over time
 Regional climates differ because of variations in
factors that influence winds and ocean currents
• Intensity of sunlight
• Distribution of land masses and seas
• Elevation
Seasonal Changes
 Seasonal changes arise because the Earth is
tilted on its axis about 23 degrees relative to the
plane of its orbit around the sun
 The hemisphere tilted toward the sun is in
summer – with longer days and more intense
sunlight – while the other hemisphere is in winter
Earth’s Tilt and Seasons
A Summer solstice (June).
Northern hemisphere is
most tilted toward sun;
has its longest day.
D Spring equinox (March)
Sun’s direct rays fall on
equator; length of day
equals that of night.
23°
Sun
B Autumn equinox
(September) Sun’s direct rays
fall on equator; length of day
equals that of night.
C Winter solstice
(December) Northern
hemisphere is most
tilted away from sun;
has its shortest day.
Fig. 48-2, p. 862
A Summer solstice (June).
Northern hemisphere is
most tilted toward sun;
has its longest day.
D Spring equinox (March)
Sun’s direct rays fall on
equator; length of day
equals that of night.
23°
Sun
B Autumn equinox
(September) Sun’s direct rays
fall on equator; length of day
equals that of night.
C Winter solstice
(December) Northern
hemisphere is most
tilted away from sun;
has its shortest
day.
Stepped
Art
Fig. 48-2, p. 862
Animation: Air circulation and climate I
Animation: Air circulation and climate II
Sunlight and Air Circulation
 The equator receives more sunlight energy than
the poles
 Regional differences in surface warming is the
start of global air circulation patterns
• Warm air rises and holds more moisture (areas of
high rainfall)
• Cool air sinks and is drier (areas where deserts
form, 30°latitude north and south)
Variation in Solar Intensity With Latitude
Factors Affecting Air Circulation Patterns
 Earth’s rotation and curvature cause air masses
that move north or south to be deflected to the
east or west
 Heating and cooling of land masses causes
differences in air pressure and regional winds
Climate and
Global Air Circulation Patterns
Initial Pattern of Air Circulation
Prevailing Wind
Patterns
D At the poles, cold air
sinks and moves toward
lower latitudes.
E Major winds near
Earth’s surface do
not blow directly north
and south because 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.
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
easterlies (winds
from the east)
westerlies
(winds from
the west)
northeast
tradewinds
(doldrums)
southeast F For example, air
tradewinds moving from 30°
south toward the
equator is deflected
to the left (west), as
westerlies
the southeast trade
winds. The winds are
easterlies
named by the
direction from
which they blow.
Fig. 48-4, p. 863
Harnessing Sun and Wind
 Unlike fossil fuels, sun energy and wind energy
are renewable resources
 Solar energy can be used directly as a heating
source, or indirectly through photovoltaic cells to
charge batteries or produce hydrogen fuels
 Wind turbines need lots of wind, but can produce
electricity day or night
48.2 Something in the Air
 Pollutants
• Natural or synthetic substances released into air,
water or soil in greater than natural amounts, that
disrupt normal processes
Polar Winds and Ozone Thinning
 Ozone molecules (O3) high in Earth’s
atmosphere (ozone layer) protect life from
harmful UV radiation
 Manmade chlorofluorocarbons (CFCs) release
chloride radicals that continue to degrade ozone
 Polar winds concentrate CFCs over the
Antarctic, resulting in an “ozone hole”
The Damaged Ozone Layer
Fig. 48-5a, p. 864
Altitude (kilometers above sea level)
80
70
mesosphere
60
50
40
stratosphere
30
20
10
0
ozone layer
troposphere
Fig. 48-5a, p. 864
Fig. 48-5b, p. 864
South
America
Antarctica
Fig. 48-5b, p. 864
Animation: How CFCs destroy ozone
No Wind, Pollution and Smog
 Smog
• An atmospheric condition in which air pollutants
accumulate to high concentration in cool, still air
because winds can’t disperse them from under a
layer of warm air (thermal inversion layer)
• Photochemical smog forms when exhaust fumes
combine with oxygen to form nitrogen dioxide and
other photochemical oxidants
Thermal Inversion and Smog
cooler air
cool air
warm air
Fig. 48-6, p. 864
cool air
warm inversion layer
cool air
Fig. 48-6, p. 864
Wind and Acid Rain
 Acid rain
• A wet acid deposition containing nitric acid,
sulfuric acid, and sulfate and nitrate salts
• Formed by interaction of pollutants (sulfur
dioxides, nitrogen oxides) with moisture in the air
• Corrodes metals, stone and other materials
• Kills trees, fish and other organisms
• Winds disperse these pollutants far from their
sources
Precipitation and pH
Windborne Particles and Health
 Wind carries airborne allergens and pollutant
particles that can irritate respiratory systems and
trigger asthma attacks on a global scale
 Vehicle exhaust is a major source of dangerous
particulate pollution
Global Distribution of
Radioactive Fallout from Chernobyl
48.1-48.2 Key Concepts
Air Circulation Patterns
 Air circulation patterns start with regional
differences in energy inputs from the sun,
Earth’s rotation and orbit, and the distribution of
land and seas
 These factors give rise to the great weather
systems and regional climates
48.3 The Ocean, Landforms, and Climate
 Air masses, oceans, and landforms affect
regional temperature and moisture levels
 The ocean, a continuous body of water, covers
more than 71 percent of Earth’s surface
 Driven by solar heat and wind friction, the
ocean’s upper 10 percent moves in currents that
distribute nutrients through marine ecosystems
Surface Currents and Climate
 Surface currents flow clockwise in the northern
hemisphere and counterclockwise in the
southern hemisphere
 On east coasts of continents, currents carry heat
energy from the equator toward the poles; on
west coasts, cold water flows toward the equator
Major Climate Zones
and Surface Currents
Animation: Major climate zones and
ocean currents
Rain Shadows and Monsoons
 Rain shadow
• When warm, moist air is blocked by a mountain
range, more rain falls on the windward side and
less rain falls on the leeward side
 Monsoon
• Differential heating of water and land causes
winds that change seasonally, resulting in heavy
rains in summer, drought in winter
Rain Shadow Effect
Prevailing winds
move moisture inland
from the Pacific Ocean.
Rain shadow on
side facing away from
the prevailing winds
makes arid conditions.
Clouds pile up and rain
forms on side of mountain
range facing prevailing winds.
4,000/ 75
moist habitats
3,000/ 85
1,800/ 125
1,000/ 25
15/ 25
2,000/ 25
1,000/ 85
Fig. 48-10, p. 867
Fig. 48-10, p. 867
Fig. 48-10, p. 867
Coastal Breezes and Land Breezes
A Afternoon;
land is warmer
than sea; breeze
blows onto the
shore
cool
air
warm air
B Evening;
sea is warmer
than land; the
breeze blows
out to sea
Fig. 48-11, p. 867
Animation: Rainshadow effect
48.3 Key Concepts
Ocean Circulation Patterns
 Interactions among ocean currents, air
circulation patterns, and landforms produce
regional climates, which affect where different
organisms can live
48.4 Biogeographic Realms and Biomes
 Biogeographic realms
• Early naturalists divided Earth’s land masses into
six realms with characteristic plants and animals
 Biomes
• Finer divisions of land realms where different
physical conditions with distinct kinds of plants
support characteristic communities
Biomes
 Global distribution of
biomes is a result of
topography, climate,
and evolutionary
history
• Most biomes occur
on more than one
continent
Global Distribution of Biomes
Animation: Major biomes
48.5 Soils of Major Biomes
 Plants obtain water and nutrients from soil
• Properties of soil impact primary production
 Each biome has a characteristic soil profile,
with different amounts of inorganic and organic
components (humus)
• Topsoil (A horizon) is most important for plants
Soil Profiles for Some Major Biomes
48.6 Deserts
Deserts
 Deserts are regions that receive an average of
less than 10 cm (4 in) of rain per year
 Most deserts are located around 30° north and
south latitudes, where dry air sinks
 Deserts tend to be hot by day and cold by night,
with nutrient-poor soils
Desert Communities
 Many plants and animals in deserts have
adaptations that minimize their need for water
• Plants: Spines or hairs retain humidity; CAM
plants open stomata only at night; shrubs have
efficient, extensive root systems
• Animals: Physiological adaptations (kangaroo
rat); burrowing (tortoise); nocturnal activity (bats)
The Sonoran Desert, Arizona
48.7 Grasslands,
Shrublands, and Woodlands
Animation: Acid deposition
Grasslands
 Grasslands form in the interior of continents
between deserts and temperate forests
• Strong winds, infrequent rain, periods of drought
• Perennial grasses fix carbon by C4 pathway
 Shortgrass and tallgrass prairies once
dominated the North American plains
• Farming destroyed extensive grass roots that
held topsoil, causing the Dust Bowl
Savannas
 Savannas are broad belts of grasslands with a
few shrubs and trees
• Warm, with rainy and dry seasons
• Fires maintain grasslands
 Found between tropical forests and hot deserts
in Africa, India and Australia
• African savannas support abundant wildlife
Three Examples of Grasslands
Fig. 48-16, p. 872
Dry Shrublands and Woodlands
 Dry shrublands
• Low rainfall, frequent fires; short, woody shrubs
• South Africa, Mediterranean regions, and
California (chaparral)
 Dry woodlands
• Low rainfall; drought-tolerant trees
• Eucalyptus forests of Australia, oak forests of
California and Oregon
California Chaparral
48.8 More Rain, Broadleaf Forests
Semi-Evergreen Forests
 Broadleaf (angiosperm) trees dominate moist
forests in both temperate and equatorial regions
 Semi-evergreen forests
• A mix of broadleaf trees that retain leaves year
round and deciduous broadleaf trees
• Tropics of Southeast Asia and India
Broadleaf Forests
 Tropical deciduous forests
• Less than 2.5 cm (1 in) of rain in dry season
• Most trees shed leaves at start of dry season
 Temperate deciduous forests
• Moderate rains throughout the year
• In fall, trees become dormant, leaves turn brilliant
colors and drop
North American
Temperate Deciduous Forest
Tropical Rain Forests
 Evergreen broadleaf forests
• Form between 10°north and south
• Warm temperatures and high rainfall, 130-200 cm
(50-80 in) per year
• Most complex biome in structure and diversity
• Shady canopy, rapid decomposition and mineral
cycling
Animation: Chernobyl fallout
Animation: Global air circulation patterns
Animation: Soil profiles
Animation: Terrestrial biomes
Animation: Thermal inversion and smog