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 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

Global Processes Determine Weather and Climate Cannot predict weather more than a few days into the future 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 Mesosphere - temperature decreases with altitude Thermosphere - helps to block harmful X-ray and UV radiation 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 (______________________)

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 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

Formation of Convection Currents Read through explanation on pages 91-92 for more detail Hadley cells- the convection currents that cycle between the equator and 30˚ north and south

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

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

Earth's Rotation and the Coriolis Effect

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

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

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

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

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

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=uySu7Zv2cbU

El Nino-Southern Oscillation

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

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

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

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 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

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 These include swamps, marshes, and bogs. Very productive biome Provide several critical ecosystem services Problem?

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 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

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

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