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Climate and Terrestrial
Biodiversity
CHAPTER 6
Weather: A Brief Introduction
Weather: result of the atmospheric
conditions in a particular area over short
periods of time, typically over hours or
days
Examples: temperature, pressure, moisture
content, precipitation, sunshine, cloud
cover, and wind direction
Weather: A Brief Introduction
Climate: the
average pattern of
weather for a
particular region
for a LONG period
of time
Warm Fronts
A warm front is the boundary between an
advancing warm air mass and the cooler
one it is replacing.
Because warm air is less dense than cool
air, an advancing warm front rises up over
a mass of cool air.
As the warm front rises, its moisture begins
condensing into droplets to form layers of
clouds at different altitudes.
Cold Fronts
A cold front is the leading edge of an
advancing mass of cold air. Since cold air is
more dense than warm air it moves in low
to the ground.
Jet Streams
These are hurricane force winds that are
blowing around up near the troposphere,
these powerful winds rising and falling
cause great influence on weather patterns.
What are Highs and Lows?
Pressure Changes!
Weather is affected by up and down
movements of masses of air with high and
low atmospheric pressure.
Air pressure results from zillions of tiny
molecules of gases (mostly nitrogen and
oxygen) in the atmosphere zipping around
at incredible speeds and hitting and
bouncing off anything they encounter.
What are Highs & Lows?
An air mass with high pressure, called a
high, contains cool, dense air that descends
toward the earth’s surface and becomes
warmer.
An air mass with low pressure, called a low,
produces cloudy and sometimes stormy
weather.
Weather Godzillas
Tornadoes (over land) and tropical storms,
cyclones, (form over warm ocean waters
and sometimes pass over land) are weather
extremes that can cause lots of damage but
can sometimes have beneficial ecological
effects.
Tornadoes
Tornadoes or twisters are swirling funnel
shaped clouds that form over land.
They can destroy houses and cause other
serious damage in areas when they touch
down on the earth’s surface.
The United States is the world’s most
tornado-prone country, followed by
Australia.
Tornadoes
Tornadoes in the plains of the Midwest
usually occur when a large, dry cold air
front moving southward from Canada runs
into a large mass of humid air moving
northward from the Gulf.
Most tornadoes occur in the spring when
fronts of cold air from north penetrate
deeply into the midwestern plains.
Tropical Storms
 Large and dangerous storms called tropical cyclones are
spawned by the formation of low-pressure cells of air over
warm tropical seas.
 Hurricanes are tropical cyclones the form in the Atlantic
Ocean; those forming in the Pacific Ocean usually are called
typhoons.
 Gale force winds circle the eye of the storm at speeds of up to
200 miles per hour.
 Moist surface winds move to the center of the storm
Climate
Climate is the long term atmospheric
conditions of a region over several decades.
The two main factors that determine a
regions climate are average temperature
and average precipitation.
Determining Air Patterns
There are four main factors that determine
global air circulation patterns.
1. Uneven heating of the earths surface.
EX: Air at the equator has more direct
sunlight so it is hotter than air below it and
above it
Determining Air Patterns
2. Seasonal changes in temperature and
precipitation
Ex. The earth is tilted which resulted in
some areas being pushed closer to the sun
and some being pushed farther.
Determining Air Patterns
3. Rotation of the earth on its axis
Ex. This causes prevailing winds which are
major surface winds that are continuously
blowing and distributing moisture over the
earth
Determining Air Patterns
4. Properties of air, water, and land also
affect global air circulation.
Seasons
Seasons in the N
and S hemispheres
are caused by the
tilt of the earths
axis.
The earths tilt is
about 23.5
degrees.
How does the ocean affect
climate?
Ocean currents and winds influence
climate by redistributing heat received
from the sun from one place to another
Oceans absorb heat from air patterns
Winds
Winds can also affect regional climates and
how some forms of ocean life are
distributed.
The ocean is in a constant flow where the
outgoing surface water gets replaced by
the upwelling cold nutrient rich water
from the bottom.
Wind Currents in the U.S.
El Nino
Every few years in
the Pacific Ocean
normal shore
upwelling's are
affected by
changes in climate
patterns called, El
Nino Southern
Oscillation (ENSO)
El Nino
In an ENSO warmer trade winds prevail
and warm the ocean waters of the northern
and southern waters of the American
coasts. This stops the cold nutrient rich
waters from reaching the surface and
affects marine life populations in the seas.
A very strong ENSO can bring about
extreme climate changes in two-thirds of
the world.
The Natural Greenhouse Effect
The Natural Greenhouse Effect is water
vapor, carbon dioxide, and other gases that
influence climate by warming the lower
troposphere and the earth’s surface.
The Natural Greenhouse Effect
The Natural Greenhouse Effect
Small amounts of certain gases play a key
role in determining the earth’s average
temperature and thus its climates.
These gases include water vapor (H20),
Carbon Dioxide (CO2), Methane (CH4), and
Nitrous Oxide (N20)
The Natural Greenhouse Effect
The Natural Greenhouse Effect
Together these gases known as greenhouse
gases, allow mostly visible light and some
infrared radiation and ultraviolet (UV)
radiation from the sun to pass through the
troposphere.
The Natural Greenhouse Effect
The earth’s surface absorbs much of this
solar energy.
This transforms it to longer-wavelength
infrared, which rises into the troposphere.
The Natural Greenhouse Effect
Some of this infrared radiation escapes into
space and some is absorbed by molecules
of greenhouse gases and emitted into the
troposphere in all directions as even longer
wavelength infrared radiation
The Natural Greenhouse Effect
Some of this released energy is radiation
into space and some warms the
troposphere and the earth’s surface.
This natural warming effect of the
troposphere is called the greenhouse
effect.
Creating Deserts and Warming
Cities
 Mountain and cities affect local and regional climates.
Creating Deserts and Warming Cities
When moist air blowing inland from an
ocean reaches a mountain range, it cools as
it is forced to rise and expand.
This causes the air to los most of its
moisture as rain and snow on the
windward slopes.
Creating Deserts and Warming Cities
As the drier air mass flows down the
leeward slopes, it draws moisture out of
the plants and soil over which it passes.
The lower precipitation and the resulting
semiarid or arid conditions on the leeward
side of the high mountains are called rain
shadow effect.
Creating Deserts and Warming Cities
Cities also create distinct microclimates.
Bricks, concrete, asphalt, and other
building materials absorb and hold heat,
and buildings block wind flow.
Creating Deserts and Warming
Cities
 Motor vehicles and the climate control systems of buildings release
large quantities of heat and pollutants.
 As a result, cities tend to have more haze and smog, higher
temperature, and lower wind speeds than the surrounding
countryside.
Tropical Temperatures
The most important factors for producing
the tropical and temperate climates is the
average annual precipitation, temperature
and soil type.
Navigation
Latitude: the distance from the equator
Altitude: the elevation above sea level
Deserts
 A desert is an area where evaporation exceeds precipitation.
 Deserts have little precipitation and little vegetation and are
found in tropical, temperature, and polar regions.
 Deserts cover about 30% of the earths surface.
 Deserts are found mostly in tropical and subtropical regions
 Desert soils have little vegetation so at night the surface
rapidly cools
Three Types of Deserts
Tropical deserts:
hot and dry most
of the year, with
few plants and
hard surfaces
Three Types of Deserts
Temperate
deserts: has high
daytime temps in
the summer and
low daytime temps
in the winter.
Vegetation consists
of cacti and shrubs
Three Types of Deserts
Cold deserts:
winters cold and
summers are warm
with low
precipitation.
Semi-deserts
In the semiarid zones between deserts and
grasslands, we find semi-desert.
This biome is dominated by thorn trees and
shrubs adapted to long dry spells followed
by brief, sometimes heavy rains.
Deserts, Continued
 Desert plants and
animals have a
number of strategies
for staying cool and
getting enough
water to survive in
hot and dry climates.
 Beat the heat or
DIE!!!
Desert Adaptations
 Cactuses don’t have
leaves which can loose
water, also they open
their pores at night
when its cooler to
intake oxygen, they
store water in inside
them for very dry
spells, and finally they
have deep roots to tap
into ground water
supplies.
Grasslands
 Three Types: Hot,
Cold, & Mild
 Grasslands have
enough precipitation
to support grasses but
not enough to support
large stands of trees.
 Grasslands are found
in tropical, temperate
and polar regions.
Prairies or Grasslands
 Prairies or grasslands
are mostly found in
the interiors on
continents. They are
formed because of a
combination of
drought, precipitation,
fire and animals
grazing that keep
large shrubs and trees
from growing.
 Grasslands in Canada
Savanna
Are grasslands that experience very warm
temperatures year round. Also they have
two dry spells and then rain the rest of the
year.
They are mainly inhabited by huge herds of
hoofed, and grazing animals.
Polar Grasslands
Polar Grasslands are occur south of the
polar ice caps.
Treeless plains covered in ice and snow
most of the year, except for a brief summer
period.
Has a layer of permafrost just below the
soil
Inhabited by small herbivores, and small
predators.
Chaparral
 Has a very mild climate with a slightly longer
winter rainy season.
 Located along the oceans in southern California
and the Mediterranean.
 Subject to many fires during the fall followed by
flooding and mudslides.
 Long, hot, dry summers make fires happen very
often.
Flooding
Chaparral Plant Life
 Consists mostly of
dense growths of low
growing evergreen
shrubs
 Few small trees with
leaves that reduce
evaporation
 During summer
become dry and
flammable.
Tropical Rain Forests
 Heavy rainfall most days out of the year.
 Found near the equator. High humidity.
 Very diverse forms of life.
 Broadleaf evergreen plants are the main
vegetation.
 Soil has very little plant nutrients.
 Very little ground plant life.
Temperate Deciduous
 Grow in places with moderate temperatures.
 Long warm summers, cold winters, and abundant
precipitation.
 Oak, Hickory, Maple, Popular, and Beech trees
dominate the plant life. Diverse ground plant life.
 Nutrient rich soil.
Temperate Deciduous
 Animal Life
Most popular animal species
is the White-Tail Deer, along
with squirrels, rabbits,
opossums, raccoons, and
mice.
Used to be home to bears,
wolves, foxes, wildcats, and
mountain lions. Most of the
predators have been killed off,
or displaced.
Evergreen Coniferous Forests
 Found just south of the arctic tundra in the
northern regions of North America, Asia, and
Europe.
 Long, dry, and extremely cold winters. Where
sunlight is available only 6-8 hours a day.
 Summers are short with mild temperatures.
Where the sun shines 19 hours a day.
Evergreen Coniferous Forest
 Plant Life
Mostly populated
by a few species of
coniferous
evergreen trees.
Spruce, fir, cedar,
hemlock, and pine
trees.
Most keep needles
all year long, and
are cone bearing.
Evergreen Coniferous Forests
Animal Life
Many small
rabbits and mice.
Contain animal
species such as
moose, wolves,
owls, and small
birds
Temperate Rain Forests
 Coastal region support these forests.
 Huge cone bearing trees such as redwoods and
Douglas firs
 Environment must be cool and moist to support
temperate rain forests.
 Cool summers and winters
 Trees depend of frequent rains
Mountain Biomes
 High elevated forests.
 Often peaks are snow covered.
 Gradually release water to lower level streams and
rivers.
 Prone to erosion, landslides, and avalanches
 Make up one fourth on the worlds land surface.
Natural Capital Degradation
 Clearing and degradation of tropical forests for
agriculture, livestock, gazing, and timber
harvesting.
 Clearing of deciduous forests of Europe, Asia and
North America, for timber, agriculture, and urban
development.
 Converting diverse forest into non diverse tree
plantations.
Natural Capital Degradation
Mountains
Landless poor migrating uphill to survive.
Timber extraction
Mineral resource extraction
Hydro-electric dams and reservoirs
Increasing tourism (such as hiking and
skiing)
Air pollution
Soil damage from off road vehicles