Global Climates and Biomes Chapter 4 Global Climates and Biomes

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 Rains did not come until 2006 What happened?? Global processes drive rainfall patterns Not understood why the rain clouds did move northward in 2003

Global Processes Determine Weather and Climate Include temperature, humidity, clouds, precipitation, wind speed and atmospheric pressure Cannot predict weather more than a few days Climate

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 Ozone layer Mesosphere - temperature decreases with altitude Thermosphere - Aurora Exosphere - Outermost layer

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 (albedo)

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

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

Unequal Heating of Earth: Albedo

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 Saturation point Adiabatic cooling- Adiabatic heating Latent heat release- when water vapor in the atmosphere condenses into liquid water and energy is released

Formation of Convection Currents Atmospheric convection currents are global patterns of air movement that are initiated by the unequal heating of Earth Read through explanation on pages 91-92 for more detail Hadley cells-

Formation of Convection Currents Intertropical convergence (ITCZ) - the area of Earth that receives the most intense sunlight Polar cells- 3rd area of air circulation – does not form distinct convection cell

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

Earth's Rotation and the Coriolis Effect Coriolis Effect- the deflection of an object's path due to Earth's rotation.

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

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

Earth’s Seasons

Ocean Currents Ocean currents are driven by a combination of: Warm water, like warm air, expands and rises. Gyres- the large-scale patterns of water circulation Redistribute heat in the ocean

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

Oceanic Circulation

Thermohaline Circulation Thermohaline circulation- oceanic circulation that drives the mixing of surface water and deep water Takes hundreds of years to complete

Heat Transport Ocean currents can affect the temperature of nearby landmasses Concern about global warming

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: http://www.youtube.com/watch?v=yCsMmajLYG4 http://www.youtube.com/watch?v=7FVZrw7bk1w (start ~0:50)

El Nino-Southern Oscillation

La nina

Rain Shadows Rain shadow – warm, dry air on leeward side of mountain, formed via: Adiabatic cooling and heating

Variations in Climate Determine the Dominant Plant Growth Forms of Terrestrial Biomes Climate affects the distribution of species Biomes- areas possessing similar temperature and precipitation patterns Therefore contain similar producer species

Location of World’s Biomes

Tundra

Boreal Forest

Temperate Rainforest

Temperate Seasonal Forest

Woodland/Shrubland

Temperate Grassland/ Cold Desert

Tropical Rainforest

Tropical Seasonal Forest/Savanna

Subtropical Desert

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

Freshwater Ecosystems

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

Lakes and Ponds Standing water Lakes are larger than ponds Distinct zones: Littoral zone – shallow area of soil and water near shore Limnetic zone – open water, as deep as light can penetrate Profundal zone – deep under the limnetic zone where light can no longer reach Benthic zone – muddy bottom of lake or pond

Lakes and Ponds

Freshwater Wetlands Aquatic biomes that are submerged or saturated by water for at least part of each year Shallow enough to support emergent vegetation Includes: Very productive biome Provide several critical ecosystem services Problem?

Marine Ecosystems

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

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

Intertidal Zone Tide conditions: High tides – stable environment Low tides – harsh environment Waves that crash onto the shore

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 But water is relatively poor in nutrients and food Coral bleaching

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 – Aphotic zone - the deeper water that lacks sufficient light for photosynthesis Chemosynthesis Bioluminescence Benthic zone – ocean floor