1. Chapter 43 The Biosphere (Sections 43.1 - 43.4)

2. 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

3. 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

4. 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

5. The Biosphere
Interactions among Earth’s oceans and atmosphere give rise to El Niño and other climate patterns
Figure 43.1 El Ni. Opposite, Ken Bradshaw rides a wave more than 12 meters (39 feet) high, during the most powerful El Ni of the past century. Above, interactions among Earth’s oceans and atmosphere give rise to an El Ni and to other climate patterns.

6. Effects of El Niño

7. Animation: Normal vs. El Niño Conditions

8. 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

9. 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

10. Earth’s Tilt and Yearly Rotation

11. 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
Figure 43.2 Earth’s tilt and yearly rotation around the sun cause seasonal effects. The 23ｰ∆ tilt of Earth’s axis causes the Northern Hemisphere to receive more intense sunlight and have longer days in summer than in winter.
C Winter
solstice (December). Northern hemisphere is most tilted away from sun; has its shortest day.
B Autumn equinox (September). Sun’s direct rays fall on equator; length of day equals length of night.
Fig. 43.2, p. 724

12. 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
C Winter
solstice (December). Northern hemisphere is most tilted away from sun; has its shortest day.
B Autumn equinox (September). Sun’s direct rays fall on equator; length of day equals length of night.
Figure 43.2 Earth’s tilt and yearly rotation around the sun cause seasonal effects. The 23ｰ∆ tilt of Earth’s axis causes the Northern Hemisphere to receive more intense sunlight and have longer days in summer than in winter.
Stepped Art
Fig. 43.2, p. 724

13. Animation: Orbit Around the Sun

14. 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

15. Variation in Intensity of Solar Energy
Figure 43.3 Variation in intensity of solar radiation with latitude. For simplicity, we depict two equal parcels of incoming radiation on an equinox, a day when incoming rays are perpendicular to Earth’s axis. Rays that fall on high latitudes A pass through more atmosphere (blue) than those that fall near the equator B. Compare the length of the green lines. Atmosphere is not to scale. Also, energy in the rays that fall at the high latitude is spread over a greater area than energy that falls on the equator. Compare the length of the red lines.

16. 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

17. 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

18. Circulation Patterns and Major Winds

19. Circulation Patterns and Major Winds
Idealized Pattern of Air Circulation
Major Winds Near Earth’s Surface
D At the poles, cold air sinks and moves toward lower latitudes.
Cooled, dry
air descends
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.
easterlies (winds
from the east)
C Air rises again at 60° north and south, where air flowing poleward meets air coming from the poles.
westerlies (winds
from the west)
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.
northeast tradewinds
(doldrums)
southeast tradewinds
Figure Global air circulation patterns.
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.
westerlies
easterlies
Fig. 43.4, p. 725

20. Circulation Patterns and Major Winds
Figure Global air circulation patterns.
Fig. 43.4, p. 725

21. Animation: Global Air Circulation Patterns
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22. 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

23. Animation: Air Circulation and Climate I
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24. Animation: Air Circulation and Climate II
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25. 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

26. 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

27. Climate and Major Surface Currents
Figure Major climate zones correlated with surface currents and surface drifts of the world ocean. Warm surface currents start moving from the equator toward the poles, but prevailing winds, Earth’s rotation, gravity, the shape of ocean basins, and landforms influence the direction of flow. Water temperatures, which differ with latitude and depth, contribute to regional differences in air temperature and rainfall.

28. 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

29. Rain Shadow Effect

30. Rain Shadow Effect
Figure Rain shadow effect. On the side of mountains facing away from prevailing winds, rainfall is light. Black numbers signify annual precipitation, in centimeters, averaged on both sides of the Sierra Nevada, a mountain range. White numbers signify elevations, in meters.
Fig , p. 727

31. Rain Shadow Effect
A Prevailing winds move moisture inland from the Pacific Ocean.
B Clouds pile up and rain forms on side of mountain range facing prevailing winds. moist habitats
C Rain shadow on side facing away from the prevailing winds makes arid conditions.
4,000/ 75
3,000/ 85
2,000/25
1,800/ 125
moist habitats
1,000/25
1,000/ 85
15/ 25
Figure Rain shadow effect. On the side of mountains facing away from prevailing winds, rainfall is light. Black numbers signify annual precipitation, in centimeters, averaged on both sides of the Sierra Nevada, a mountain range. White numbers signify elevations, in meters.
Fig , p. 727

32. Rain Shadow Effect
Figure Rain shadow effect. On the side of mountains facing away from prevailing winds, rainfall is light. Black numbers signify annual precipitation, in centimeters, averaged on both sides of the Sierra Nevada, a mountain range. White numbers signify elevations, in meters.
Fig , p. 727

33. Rain Shadow Effect
Figure Rain shadow effect. On the side of mountains facing away from prevailing winds, rainfall is light. Black numbers signify annual precipitation, in centimeters, averaged on both sides of the Sierra Nevada, a mountain range. White numbers signify elevations, in meters.
Fig , p. 727

34. Coastal Breezes

35. Coastal Breezes A In afternoon; the land is warmer than the sea, so
the breeze blows onto shore.
cool air
warm air
Figure 43.7 Coastal breezes.
Fig. 43.7a, p. 727

36. Coastal Breezes
B In the evening, the sea is warmer than the land; the breeze blows out to sea.
Figure 43.7 Coastal breezes.
Fig. 43.7b, p. 727

37. 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.
Figure 43.7 Coastal breezes.
Stepped Art
Fig. 43.7, p. 727

38. 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

39. 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

40. Animation: Major Climate Zones and Ocean Currents
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41. 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

42. 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

43. Major Biomes and Marine Ecoregions
Figure 43.8 Global distribution of major categories of biomes and marine ecoregions.

44. Major Biomes and Marine Ecoregions
Figure 43.8 Global distribution of major categories of biomes and marine ecoregions.

45. Primary Productivity

46. 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

47. Animation: Rain Shadow Effect
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48. Animation: Major Biomes
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