Transcript Chapter 4

Chapter 4
Climate and Biomes
Atmosphere
 Weather is short term conditions of atmosphere
 Climate is long term conditions
 5 major processes influence climate/weather: unequal heating of
earth, convection currents, Coriolis effect, tilt, and oceans
 Atmosphere has 4-layers:
1.
Troposphere (0-20km): bottom layer, densest, where most
weather and mixing occurs, temps get colder with height
2.
Stratosphere (20-50km): second layer, gets warmer with height,
contains ozone layer that absorbs UV light
3.
Mesosphere (50-80km) – third layer, coldest, meteorites burn up
4.
Thermosphere – top layer, warmest, absorb gamma rays

Atmosphere protects organisms from radiation and it regulates
temperatures
1. Unequal Heating
 Atmosphere is heated unevenly for 2 reasons
1. Tilt of the earth
2. Some areas on earth reflect more sunlight
than other areas (albedo)
 White surface has higher albedo than
black surface

This uneven heating of the atmosphere drives
convection currents in the atmosphere
2. Atmospheric Convection Currents
Air has 4 properties that determine how it will circulate
1. Density: less dense air rises (warm), more dense air
sinks (cold)
2. Water vapor capacity: warm air can hold more water
vapor (saturation point) which is less dense
3. Adiabatic heating/cooling:
1.
When air rises, pressure decreases and air expands and temps
lower due to less friction between air molecules
2.
When air sinks, pressure increases and air compresses and
temps rise due to more friction between air molecules
4. Latent heat release: when air condenses, the energy
that evaporated it is released and air warms
(2). Formation of Convection Currents
• Air rises in warm, moist tropics
• Rising air experiences lower atmospheric pressure and
adiabatic cooling until it reaches saturation point
• This leads to condensation which releases latent heat
• Eventually air cools and spreads out and begins to
sink around 30⁰ latitude (deserts)
• When sinking air hits the ground, it spreads in all
directions completing the cycle, called a Hadley cell
• Air re-converges at the equator, called the
intertropical convergence zone (ITCZ)
• Polar regions cause additional Hadley cells
3. Earth’s Rotation and Coriolis Effect
 Earth rotates faster at equator than poles
 Objects’ paths get deflected due to the rotation of earth.
This is known as the Coriolis effect
 This deflects winds and sets up weather patterns
 Trade winds blow towards the equator between 0- 30°.
They meet at the equator and rise creating calm winds
called the doldrums
 Where the air sinks at 30° is the horse latitudes
 Air moves north from here, Coriolis force deflects it to
right, and get westerlies (40°-60°)
 At poles, the air sinks and moves towards the equator, but
gets deflected to right. This creates polar easterlies
4. Earth’s Tilt and Seasons
• Earth is tilted 23.5⁰
• When northern hemisphere is pointed towards the
sun they experience summer
• When northern hemisphere is pointed away from the
sun they experience winter (southern hemisphere is
opposite)
• Vernal/automnal equinoxes, everywhere receives 12h
daylight
• Poles have 6 months of darkness and 6 months of
daylight
5. Ocean Currents
• Currents driven by temp, gravity, prevailing winds,
Coriolis effect, and continents
• Water is warmer at the equator, so it expands and rises.
This makes the water higher then the rest of earth and
gravity takes over
• Winds and Coriolis effect start ocean currents and deflect
them. Called gyres (transport heat)
• Upwelling (rising of water) occurs along coastlines
• Thermohaline circulation is when water is saltier, making
it more dense, so it sinks
• ENSO (El Nino – Southern Oscillation– when ocean
currents change direction, thus affecting climates
Rain Shadows
• Air rises on one side of a mountain range and
moisture condenses out
• On other side, air sinks preventing clouds and it
remains dry
• Dry region is called a rain shadow
Altitudes create “latitudinal”
patterns
• Vegetative communities rapidly change along
mountain slopes
• The climate varies with altitude
• A mountain climber in the Andes
• Begins in the tropics and ends
on a glacier
• Rainshadow effect = air going
over a mountain releases
moisture
• Creating an arid region
on the other side
Biomes
• Biomes are large regions characterized by a specific
type of climate and certain types of plant and
animal communities
• Largest category scientists use to classify ecosystems
• Each biome has many ecosystems
• Biomes described by vegetation because that
determines organisms and amount of vegetation is
determined by climate
• At altitude and latitude increase, temps decrease
Tundra
 Climate: Very cold year around and little precip (driest biome)
 Location: North of the arctic circle
 Plants:
1.
Mostly mosses and lichen (which don’t need soil)
2.
Rest of plants are low and have wide roots to keep them stable in
winds
3.
Soil is permafrost which makes it hard for trees to grow, and low in
nutrients

Animals: Birds common in summer, caribou, wolves, deer, rabbits,
foxes, bears
 Threats: Oil excavation and pollution. Food chain is simple, so small
change has dramatic consequences
 Other: CO2 sink, none in southern hemisphere
Boreal Forest (taiga)
 Climate: Long cold winters, short mild summers, and
fairly dry
 Locations: Just below the arctic circle
 Vegetation (slow decomposition allows for little):
1.
Dark forest floor because thick canopy blocks sunlight
3.
Trees are conifers (seeds in a cone)
2.
4.
Branches near tops of trees
Leaves thin, pointy, and waxy to store water and shed snow
 Animals:
1.
2.
3.
Many insects in summer
Migratory birds to feed on insects
Some large herbivores and thick-coated carnivores
Threats: global warming and oil excavation

Other: soil low in nutrients, lots of lakes from last ice age
Temperate Rain Forest and Temperate Deciduous
Forest
 Climate:
1.
Temperate rain forest = wet year around with moderate temps
2.
Temperate deciduous forest = Moderate precip and large temp range (4-seasons)

Location: TRF = northwest US, TDF = Mid latitudes

Plants:
1.
TRF = Draped with mosses, lichens, and ferns
2.
TDF = Many tall trees and many shrubs since plenty of light. Lose leaves

Animals:
1.
Many animals and insects
2.
In TDF, many animals fly south or hibernate and shed fur
 Threats: overdevelopment, logging, fossil fuels, agriculture
Woodland/Shrubland Chaparral
 Climate: Dry and warm, but not quite desert dry
 Location: Mostly around 30° latitude near water
 Plants:
1. Many evergreen shrubs
2. Plants oily to burn and to retain water
 Animals: most animals camouflage, many have
scales, and most small
 Threats: human development
 Other: wild wild west
Tropical Rain Forest
Climate: warm and wet year around
Animals:
Location: near the equator
1.
Adapt to use resources, escape predators,
and capture prey
2.
Built to climb trees
3.
Bright colors, spikes, loud noises…
Plants:
1.
Emergent trees get direct sunlight
2.
Dense canopy absorbs 95% of sunlight
3.
Understory has large leaves to absorb little
light
1.
Destroyed for logging, oil, and agriculture
4.
Leaves have drip tips for water to runoff
Animals and plants are used for trading
5.
Many vines climb trees to reach sun
Threats:
2.
Savannah
 Separate desert biomes from tropical rain forest biomes
 Climate: Short wet season, long dry season, and warm year round
 Location: Close to the equator
 Plants:
1.
Full of grasses (many sharp and bitter) with scattered trees
2.
Trees have large horizontal roots to absorb water in dry season and
thick bark to survive fires

Animals:
1.
Full of grazing animals and their predators
2.
Herbivores have many heights to limit competition
3.
Many have long legs or wings to migrate
 Threats: poaching, hunting, agriculture, grazing
 Other: Many grassfires
Temperate Grasslands
 Climate: Hot summers, cold winters, and inconsistent
precipitation
 Locations: Interior of continents, often surrounded by mountains
which limit rainfall
 Plants:
1. Very fertile soil
2. Many grasses and flowers which are perennials
3. Prairies = tall grasses (wetter) Steppes = short grasses (drier)
4. Very few trees because limited rainfall

Animals: Many smaller animals that can hide in grass and their
predators
 Threats: over farming
Desert
 Climate: very dry and mostly warm to very hot year around (with
large daily temp range)
 Location: Most around 30° latitude
 Plants:
1.
Little to no vegetation
3.
Spines keep thirsty animals away and conserve water
2.
Plants called succulents have thick, fleshy stems to store water (cactus).
Animals:
1.
Animals are mostly small reptiles, spiders, and insects
2.
Most have shells or scales to trap water in
3.
Most bury themselves underground
4.
Most nocturnal
Other:
1. Soil rich in minerals but low in nutrients
2. Can be cold
Aquatic Ecosystems
• Aquatic ecosystems are categorized by salinity, depth,
nutrients, and water flow
• Streams and rivers: rivers larger and carry more water.
Very little plant matter (most washes from land). Slower
they flow typically means more life
• Lakes and ponds: have standing water that gets too deep to
support rooted plants. Lakes typically larger and have
water flowing in an out
• Littoral zone: shallow area near shore. Algae and cattails. Most
life
• Limnetic zone: not rooted plants. Phytoplankton are producers.
Extends as deep as sunlight penetrates
• Profundal zone: region below where sunlight reaches. Not
productive (few decomposers)
• Benthic zone is the muddy bottom (low temps and oxygen levels)
Freshwater Wetlands
• Wetlands are land covered with water during
parts of the year
• Most found in the southeastern US
1.
Filter pollutants and sediments
2.
Prevent flooding by storing excess water
3.
Provide homes for many types of organisms
4.
Recycle nutrients and sinks (CO2)
2-types: marshes and swamps
• Marshes do not contain woody plants
• Swamps contain woody plants
• Low oxygen levels, so slow decay
Salt Water Wetlands
An estuary is where freshwater meets saltwater. Very productive
ecosystem with large biodiversity:
1.
Many nutrients trapped where currents meet
2.
Tides circulate nutrients
3.
High level of light penetration
4.
Many plants in and around
Salt marsh is a muddy wetland near estuary where nutrients pile
up
• Dry during low tide, wet during high tide
•
Mangrove swamps are swamps in tropical areas that are
dominated by mangrove trees. Protect shore from erosion and
provide shelter
•
Rocky shores have many more plants and animals than sandy
ones.
Coral Reefs
• Coral reefs are limestone ridges built by tiny animals
• It is made of skeletons that accumulate (limestone)
• Found in shallow, tropical water
• They eat microscopic organisms with tentacles
• Symbiosis with algae (coral release CO2, algae uses
that for photosyn and creates sugars that coral uses)
• One of most diverse ecosystems in world
• If water temp or salinity changes, they can die
• Oil spills, sewage, pesticide, runoff, harvesting (for
jewelry) and over fishing have killed reefs
The Open Ocean
• The depth that light can penetrate in the
open ocean is dependent on the amount of
sediment and algae suspended in the water.
• 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- The process that occurs in
the aphotic zone when some species of
bacteria use methane and hydrogen sulfide
to generate energy.