Chapter Four: Global Climates and Biomes

Layers of the Atmosphere

Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere

Insolation

The measure of solar energy striking a specific area in a given amount of time

Albedo Effect

Reflection of the sun off the Earth - axial tilt causes seasons

Four properties of air that determine circulation

1. Density

2. Capacity to hold water vapor (saturation point)

3. Changes in pressure (adiabatic heating/cooling)

4. Production of heat through condensation (latent heat)

Adiabatic Cooling/Heating

Air rises, decrease in pressure, air spreads out and cools, reaching its saturation point - with heating, air sinks, the molecules condense and heat

Latent Heat

As water condenses, latent heat is released from the molecules and that makes air expand and rise further, causing bigger storms

Atmospheric Convection Currents

• Adiabatic cooling causes water to reach the saturation point

• As water condenses, latent heat is released

• Happens continuously over the equator and air then moves upward in the troposphere

• Air then chills from adiabatic cooling with little water vapor at this point

• Cold dry air sinks and experiences higher pressure and reduced volume (adiabatic heating)

• Air is now hot and dry and circulates back to starting point

Hadley Cells

Type of convection current driven by intense solar radiation (insolation) near the equator (30 N to 30 S) - unequal warming at tropics causes air to expand and rise - rising air cools, condenses, and then rains over tropics - after adiabatic cooling the cold dry air moves horizontally North and South of he equator and descends - this air is exposed to adiabatic heating as it sinks, causing hot dry regions (deserts) - this air then flows back toward the equator to complete the cycle

Intertropical Convergence Zone (ITCZ)

When Hadley cells converge

Polar Cells

Formed by air that rises at 60 N and 60 S and sinks at the poles

Ferrel Cells

Between Hadley cells and Polar cells - do not form distinct cells, but are driven by the circulation of the Hadley and Polar cells

Coriolis Effect

Deflection of an object’s path due to the rotation of Earth - the planet’s surface moves faster at the equator than at higher altitudes (deflects air to the west) - if earth didn’t rotate the convection cells would simply move north and south and back again

Rain Shadows

A region with dry conditions found on the leeward side of a mountain range (adiabatic heating) - humid winds from the ocean cause precipitation on the windward side - rains as it moves up the mountain (adiabatic cooling) and warms after it crosses and lowers (adiabatic heating)

Ocean Currents

Flow of water is an important factor in global climates because it moves warm and cold water to different parts of the globe - driven by temperature, gravity, prevailing winds, Coriolis effect, salinity, and location of continents

Gyres

A circular ocean current that moves clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere - redistributes heat in the ocean

Upwelling

The upward movement of ocean water toward the surface bc of diverging currents - carries with them many nutrients from the bottom of the ocean

Thermohaline Circulation

Drives the mixing of surface water and deep water - moves heat and nutrients around the globe - driven by surface water with high levels of salt (higher salinity has more density which makes water sink) - affects temperature of nearby landmasses - global warming changes salinity levels, alters thermohaline circulation

El Nino - Southern Oscillation

Every 3-7 years - tropical current moves in the opposite direction due to a reversal of wind and water currents in the South pacific - reduces upwelling off South American coast and leads to reduction in fish populations - cooler/wetter in Southeast US and dry in Southern Africa and Southeast Asia - La Nina is the opposite

Reduction in crop production (too much rainfall, drought, etc.) - both El Nino and La Nina

Terrestrial Biomes

Categorized by a combination of average annual temperature and precipitation - contain distinctive plant growth that are adapted to that climate - biomes are large geographical areas that are home to a large number of species

Climate Diagrams

1. Patterns of temperature and precipitation

2. How a biome changes throughout the year

3. When the temperature is warm enough for plants to grow

4. Relationship between precipitation, temperature, and plant growth

5. How humans use different biomes

Tundra

Cold, treeless biome - low growing vegetation - arctic, antarctic, and alpine tundra - short growing season, permafrost, little precipitation, slow decomposition - woody shrubs, mosses, lichens, etc. - arctic fox, polar bears, penguins - global warming is a threat (melting of permafrost, ice, etc.)

Boreal Forest/Taiga

Coniferous cone-bearing trees - cold climate - slow decomposition - soils have low nutrients - low precipitation - pine, spruce, birch - beavers, wolverines, moose - deforestation because of extensive logging

Temperate Rainforest

Moderate temperature - high precipitation - coastal biome - mild summers and winters - year-round growing season (highest productivity) - supports growth of large trees (fir, spruce, hemlock) - prone to logging - slow decomposition and most nutrients are taken up by trees or leached by rain

Temperature Seasonal Forest (us)

Warm summers and cold winters - broadleaf deciduous trees (maple, oak) - rapid decomposition so more nutrients - good biome for agriculture

Woodland/Shrubland

How dry summers and mild rainy winters - year-round growing season - plant growth hindered by varying temperatures and rain throughout the year - wildfires/droughts - yucca, scrub oak, sagebrush - low nutrient soil - too much development and increasing wildfires

Temperature Grassland/Cold Desert

Cold, harsh winters and hot dry summers - fires common, limited plant growth - grasses and non-woody flowering plants - bison, prairie dogs, kingsnake, quail, etc. - soil is high in nutrients so grasslands are productive (agriculture)

Tropical Rainforests

Warm temperatures and abundant rainfall - high productivity - rapid decomposition - few nutrients in soil bc of abundant plants - deforestation hurts them - most biodiversity - forests have distinct layers (canopies to fight for sunlight)

Tropical Seasonal Forests/Savanna

Warm temperatures with distinct wet and dry season - caused by ITCZ - trees drop leaves in dry season - fast decomposition but limited rain slows plant growth - used for agriculture/grazing - gazelles, zebras, lions, cheetahs

Subtropical Desert

Hot temperatures, extremely dry sparse vegetation - cacti and succulents - camels, roadrunners, tortoises - rain can change landscape for brief periods - climate change and draining of groundwater hurt this biome

Freshwater Biomes

Streams, rivers, lakes, and ponds

As water flow changes, biological communities change:

• Fast-moving streams have few plants/algae as producers (organic matter from land is bottom of food chain)

• Once streams continue to form large rivers, they slow and sediment falls to the bottom to encourage growth of plants

Artificial Eutrophication (fertilizers, detergents)

Zones of Lakes and Ponds

• Littoral Zone: shallow area of soil and water near the shore where algae and emergent plants live

• Limnetic Zone: open water where rooted plants cannot survive - phytoplankton are main producers

• Profundal Zone: below open water where sunlight does not reach - bacterial decomposition occurs

• Benthic Zone: muddy bottom

Productivity Levels of Lakes and Ponds

• Oligotrophic: low productivity because of low nutrients

• Mesotrophic: moderate productivity

• Eutrophic: high productivity

Freshwater Wetlands

Submerged or saturated with water for at least part of each year - shallow enough to support emergent vegetation (swamps have emergent trees, marshes have non-woody plants like cattails, bogs are acidic and contain sphagnum moss and spruce trees) - very productive - filter pollutants (essential habitats) - human impacts are sedimentation and industrialization

Salt Marshes

In temperate climates with emergent, non-woody plants - found within an estuary - fish, shellfish, birds - development and pollution are issues

Mangrove Swamps

Near tropical/subtropical coasts - salt-tolerant trees - protect coastlines from erosion - provide sheltered habitats - destroyed for agriculture and development

Intertidal Zone

Narrow band of coastline between high and low tide - stable during high tide - harsh during low tide because organisms are exposed to direct sunlight (high temps) - barnacles, sponges, algae, mussels, and crabs

Coral Reefs

Warm shallow water beyond shoreline - low nutrients in water because corals contain single-celled algae - live in large colonies - large diversity of species - ocean acidification and increased temperature cause coral bleaching :(

Open Ocean

Deep water where sunlight doesn’t reach the bottom - in deeper waters bacteria use chemosynthesis to generate energy

Open Ocean Zones

• Photic Zone: upper layer with photosynthesis

• Aphotic Zone: deeper layer with no photosynthesis

• Benthic Zone: ocean floor