2.4: Climate And Biomes Flashcards
What is a biome?
A collection of ecosystems sharing similar climatic conditions and as a result that same types of vegetation
Each biome has characteristic limiting factors that affect productivity and biodiversity
Ex: desert -> water limit plant growth
Tundras -> low temp + permafrost limit plant growth
What are the 5 major biome groups?
Freshwater
Marine
Forest
Grassland
Desert
Tundra
What are factors that determine the distribution of biomes?
Generally climatic and geographical factors
Ecologically similar characteristics
Average temp
- affect rate of photosynthesis and respiration in plants
Average rainfall/precipitation
- limiting factor for many biomes
Insolation (amount of suns energy reaching the surface)
- affect temp, rate of photosynthesis in plants
Mostly determined by temp and precipitation
How does latitude effect insolation?
Sun heat up air in atmoshpere -> temp depends on latitude
- equator closest to the sun -> air warmest there
- air colder closer to the poles
Due to earths curvature and angle of earths tilt
What are the characteristics of the Hadley cell?
closest to the equator, 0° - 30°
- largest cell
- trade winds blow from tropical regions to equator and travel to east
-> near equator winds meet -> hot air rises -> form
thunderstorm/tropical rainstorms
-> from top of storm air flow to higher latitude -> cools ->
sink over subtropical regions
-> brings dry cloudless air -> warmed by sun as descend -> climate warm and dry
What is the ITCZ?
Inter tropical convergence zone
-> where Hadley cells converge
High insolation -> air heated -> less dense -> tropical tropopause
High heat -> high evaporation -> condense to form large cumulonimbus clouds -> high precipitation
= tropical rainforest
What happens between the Hadley and Ferrel cells?
Air cools -> forms area of high pressure -> mid latitude tropopause
- air is still relatively hot
Little cloud formation -> low precipitation
= deserts
What happens between the Ferrel and polar cells?
Air meets cooler air from polar region (more dense) -> polar air pushes relatively warmer air of Ferrel cell up
-> large amount of cloud formation + precipitation = polar front
(Extremely polar regions -> less cloud formation)
= tundra, temperate forest
How does the tricellular model influence biome distribution?
Tricellular -> impact precipitation, temp, latitudes
90° - 60°
- descending cold air -> low temp and precipitation
Evergreen coniferous forest
Tundra
60° - 30°
- variable weather -> interaction between warm + cold air masses -> temperate climate + moderate precipitation
Desert
Temperate deciduous forest
Grassland
30° - 0°
- rising warm air -> high rainfall
Tropical deciduous forest
Tropical rainforest
Savanna
How does the ocean store and distribute heat?
Ocean -> large heat reservoir
- absorb solar radiation -> penetrate surface laters
-> absorbed mainly bu top layer
-> warms water -> store of thermal energy
Ocean current -> distribute huge amount of heat energy around planet -> surface ocean currents driven by winds+earths rotation -> transport warm water from equator to poles affect climate in different locations
How has climate change affected biomes?
Biomes -> consequence of climate
Climate change -> global warming = biome change
- significant impact on ecosystems
- biomes move
- change in plant+animal species in area
General trends:
biomes move polewards
Less rainfall -> forest becoming deserts
Change in ocean currents
-> warmer biomes expand
-> colder biomes contract
By 2100 -> 1.5-4.5°C increase
What is weather?
The current state of the atmosphere at a specific time and place
-> can change rapidly
Incudes things like:
Temperature
Humidity
Cloud cover
Precipitation
Wind speed
Air pressure
What is climate?
The long-term average of weather condition in a particular region or location
- usually average over 30+ years
-> overall patterns, trends, variations in atmospheric factors over relatively long periods of time
Influenced by solar radiation, atmospheric circulation patterns, ocean currents, land features, greenhouse gas concentration etc.
What are different subcategories of biomes?
forest biomes (trees)
- tropical rainforest
- temperate rainforest
- boreal rainforest
Grassland biomes (grasses and herbaceous plants)
- savannas
- temperate grassland
Desert biomes (low rainfall, cacti, drought resistant plants)
- hot desert
- cold desert
- coastal desert
- semi-arid desert
Tundra biomes (high latitudes, low temp, permafrost)
- arctic tundra
- alpine tundra
How does biome shift occur?
Range shifts:
Species move to new areas to find suitable conditions as their current habitat become less hospitable
Biome type change:
When biome transitions to new type (ex: forest -> savanna)
What are the impacts of biome shifting?
Species move to new area/experience change in habitat -> new competition, predation, disease
-> decline in population or extinction
Impact on vital services that ecosystem provide (especially to humans):
- water regulation
- nutrient cycling
- carbon sequestration
What is the tricellular model of atmospheric circulation?
Shows the direction of air flow and ascent/descent of air masses in convection cells that determine the earths climatic zones
Global atmospheric circulation:
The worldwide system of winds that move solar heat energy from the equator to the poles to reach a balance in temperature
Helps understand:
Global distribution of biomes
Ecological characteristics
Predict biome shifts
How does wind form?
Air always moves from areas of high pressure -> low pressure
- movement generates wind
Wind - large scale movement of air due to difference in air pressure
- pressure difference during to sun heat surface unevenly
- irregular heating -> pressure cells
How do wind pressure cells work?
Basically a convention current (roughly circular)
Moves extra heat from equatorial regions to other parts of earth
Sun heats the surface -> air expands -> rises
Air rises -> surface pressure lowers + increases pressure in atmosphere
Air cools in atmosphere -> denser -> sinks -> lower the atmospheric pressure
Air sink -> surface pressure rises
= pressure difference
- to balance air rushes to low pressure area -> wind
- greater the pressure difference = stronger winds
What are the characteristics of the Ferrel cell?
Middle cell 30° - 60°
Most complicated -> moves in opposite direction from other
Air in this cell joins sinking air of Hadley -> travel at low/mid altitude -> rises along border of polar cell
Accounts for frequent unsettled weather
What are the characteristics of the polar cell?
Smallest and weakest (60° - 90°)
Air is cold -> sinks -> creates high pressure over highest latitudes
Cold air follows out towards lower altitudes at surface -> slightly warmed -> rises and returns to poles/high altitudes
What is ocean currents impact on climate?
Redistribution of heat -> regulate global climate
- help moderate temp extremes
Warm ocean current -> milder, warmer weather conditions to coastal regions
Cold ocean currents -> cool down coastal regions
Oceanic heat transport -> affect marine ecosystems
-> affect productivity, distribution of marine species, etc.
