1. Global Climates and Biomes
Chapter 4
Global Climates and Biomes

2. Floods, Droughts and Famines
Western Kenya - April 2003 – heavy rains
Flooded villages, roads, bridges
Results…
People could not recover or start rebuilding
In northern Kenya – drought resulting from lack of summer rain
3 year drought, caused many problems
Rains did not come until 2006
What happened??
Global processes drive rainfall patterns
Not understood why the rain clouds did move northward in 2003

3. Global Processes Determine Weather and Climate
Cannot predict weather more than a few days into the future
Climate

4. Earth's Atmosphere 5 layers of gases
Troposphere- the layer closest to surface extending roughly 16 km above Earth
Stratosphere- above the troposphere, this extends from roughly 16 to 50 km
Mesosphere - temperature decreases with altitude
Thermosphere - helps to block harmful X-ray and UV radiation
Exosphere - Outermost layer

5. Unequal Heating of Earth
As the Sun's energy passes through the atmosphere and strikes land and water, it unequally warms the surface of Earth – WHY?
The variation in angle at which the Sun's rays strike
The amount of surface area over which the Sun's rays are distributed
Some areas of Earth reflect more solar energy than others (______________________)

6. Unequal Heating of Earth: Variation in angle at which the Sun's rays strike

7. Unequal Heating of Earth: The amount of surface area over which the Sun's rays are distributed

8. Unequal Heating of Earth: Albedo

9. Atmospheric Convection Currents
Air has four properties that determines its movement:
Density-
Water vapor capacity- warm air has a higher capacity for water vapor than cold air
Adiabatic cooling- air rises in the atmosphere  pressure decreases and the air volume increases  expansion lowers temperature of air
Latent heat release- when water vapor in the atmosphere condenses into liquid water and energy is released

10. Formation of Convection Currents
Read through explanation on pages for more detail
Hadley cells- the convection currents that cycle between the equator and 30˚ north and south

11. Formation of Convection Currents
Intertropical convergence (ITCZ) - the area of Earth that receives the most intense sunlight
Polar cells- the convection currents that are formed by air that rises at 60˚ N and S and sinks at the poles (90˚ N and S)
3rd area of air circulation –
Responsible for locations of rainforests, deserts, and grasslands

12. Earth's Rotation and the Coriolis Effect
Earth’s rotation has important influence on climate
The surface moves much faster at the equator than in mid-latitude and polar regions

13. Earth's Rotation and the Coriolis Effect

14. Earth's Rotation and the Coriolis Effect
The prevailing winds are produced by a combination of atmospheric convection currents and the Coriolis effect
Trade winds
Westerlies
Easterlies

16. Earth's Tilt and the Seasons
Earth's axis of rotation is tilted 23.5˚
Earth’s orbit therefore causes most regions to experience seasonal changes

18. Ocean Currents Ocean currents are driven by a combination of:
Warm water, like warm air, expands and rises.
Tropical water surface is ~8cm higher in elevation than mid-latitude waters
Gyres- the large-scale patterns of water circulation
Redistribute heat in the ocean

19. Upwelling
Upwelling- as the surface currents separate from one another, deeper waters rise and replace the water that has moved away
Important!

20. Thermohaline Circulation
Thermohaline circulation- oceanic circulation that drives the mixing of surface water and deep water
Driven by…
Takes hundreds of years to complete

21. Heat Transport
Ocean currents can affect the temperature of nearby landmasses
For example, England's average winter temperature is approximately 20 ˚ C (36˚F) warmer than Newfoundland, Canada, which is located at a similar latitude
Concern about global warming

23. El Nino-Southern Oscillation
Interaction of the Earth's atmosphere and ocean cause surface currents in the tropical Pacific Ocean to reverse direction
Occurs every 3 to 7 years
Video to check out:

24. El Nino-Southern Oscillation

25. Rain Shadows
Rain shadow – warm, dry air on leeward side of mountain, formed via:
Air containing large amount of water vapor moves inland from ocean  meets the windward side of a mountain range  air rises and begins to experience adiabatic cooling.
Causes clouds formation  precipitation falls
The cold, dry air then travels to the leeward side  it descends and experiences higher pressures  cause adiabatic heating

26. Variations in Climate Determine the Dominant Plant Growth Forms of Terrestrial Biomes
Climate affects the distribution of species
Biomes-
Therefore contain similar producer species
affects the distribution of species
Organisms possess distinct growth forms due to adaptations to local temperature and precipitation patterns.
Biomes- The presence of similar plant growth forms in areas possessing similar temperature and precipitation patterns.
- animal species are also usually fairly distinctive to a biome

27. Aquatic Biomes are Categorized by Salinity, Depth, and Water Flow
Salinity – amount of salt dissolved in water
Temperature still important…
2 broad categories:
Freshwater
Marine

28. Streams and Rivers Flowing fresh water
Originates from underground springs or as runoff from rain or melting snow.
Streams (creeks) - narrow and carry relatively small amounts of water
Rivers - wider and carry larger amounts of water
Water flow affects biological communities
Rapids – stretches of turbulent water in streams and rivers

29. Lakes and Ponds Standing water Lakes are larger than ponds
There is no clear point at which a pond is considered large enough to be called a lake
Distinct zones:
Littoral zone –
Limnetic zone –
Profundal zone –
Benthic zone – muddy bottom of lake or pond

30. Lakes and Ponds

31. Freshwater Wetlands
Aquatic biomes that are submerged or saturated by water for at least part of each year
Shallow enough to support emergent vegetation
These include swamps, marshes, and bogs.
Very productive biome
Provide several critical ecosystem services
Problem?

32. Salt Marshes Found along the coast in temperate climates
Contain non woody emergent vegetation
One of the most productive biomes in the world
Ecosystem services

33. Mangrove Swamps Found along tropical and subtropical coasts
Contain trees whose roots are submerged in water
Ecosystem services

34. Intertidal Zone
Narrow band of coastline that exists between the levels of high tide an low tide
Tide conditions:
High tides – ___________________ environment
Low tides – ___________________ environment
Waves that crash onto the shore

35. Coral Reefs Found in warm, shallow waters beyond the shoreline
Coral – tiny animals that secrete a layer of limestone (calcium carbonate) to form external skeleton
Earth's most diverse marine biome
But water is relatively poor in nutrients and food
Coral bleaching

36. The Open Ocean – Past the Intertidal Zone
The depth that light can penetrate in the open ocean is dependent on the amount of sediment and algae suspended in the water
Zones:
Photic zone - the zone that receives enough light to allow photosynthesis to occur.
Aphotic zone - the deeper water that lacks sufficient light for photosynthesis
Chemosynthesis
Bioluminescence
Benthic zone – ocean floor