WEATHER AND
CLIMATE
Weather – the day-to-day
properties such as wind
speed and directions,
temperature, amount of
sunlight, atmospheric
pressure and humidity.
Climate is determined by
two main factors:
1) average annual
temperature
2) average annual
precipitation
WEATHER AND CLIMATE
The weather and climate of any given
area is the result of the Sun
unequally warming the
Earth and the rotation of the Earth.
The latitude which receives the most
direct sunlight throughout the year is
0° …. The equator.
Global Air Flow Patterns
The motion of air around the globe is the result of solar
heating, the rotation of Earth, and the physical
properties of air, water and land.
• There are 3 major reasons that Earth is unevenly
heated:
1) More of the Sun’s rays strike the Earth at the equator
than strike the poles.
2) The tilt of Earth’s axis points regions toward or away from
the Sun.
3) Earth’s surface at the equator is moving faster than the
poles (aka Coriolis Effect). This causes the motion of the
air to curve forming major prevailing winds.
Seasonal
• Occur because the
earth’s axis is tilted
Changes
• Creates opposite
seasons in the
northern and
southern
hemisphere
• Factor that
determines global
air circulation
patterns
Winter
(northern hemisphere
tilts away from sun)
Spring
(sun aims directly
at equator)
23.5°
Solar
radiation
Summer
(northern hemisphere
tilts toward sun)
Fall
(sun aims directly at equator)
Stepped Art
Fig. 5-3, p. 102
http://www.usatoday.com/weather/tg/wglobale/wglobale.htm
Air Temperature
• As solar energy reaches the Earth, equatorial
regions heat up more than the poles.
• Warm air and water at the equator travel
poleward while cold air and water at the poles
travel equatorward in an attempt to equalize this
temperature contrast.
• It is the atmosphere's continual struggle for
temperature balance that brings us our changing
weather.
Convection currents
Convection currents are the
vertical movement of air due to
atmospheric heating and
cooling.
Warm, moist air rises (less
dense). The higher altitude has
less pressure and is colder,
causing the air to cool and
expand. This process is known
as adiabatic cooling. As the air
cools, it is unable to hold much
moisture, and precipitation
occurs. Adiabatic warming
occurs as the now cool air
descends (more dense) and
becomes subject to the lower
atmosphere’s higher pressure.
Say That Again…..
• As air near the Earth’s surface warms, all of
the following occur
– Air rises
– Air expands
– Adiabatic cooling occurs
– Water vapor condenses causing precipitation
Hadley Cells create major
weather pattern due to
adiabatic cooling and
adiabatic warming.
A large Hadley cell starts
its cycle over the equator
where warm air
evaporates and rises; cools
and drops rain. This
process accounts for the
abundant tropical
rainforests.
The cool dry air then
descends about 30° north
and 30° south of the
equator, forming deserts at
these latitudes.
Rain Shadow Effect
• The rain shadow effect allows the same
process to occur more locally.
• Occurs when moisture-rich air encounters a
mountain range and is deflected up the mountain
range. As the air moves up, it cools and water
precipitates out on the windward side of the
mountain. By the time the air mass reaches the
opposite side of the mountain, it is virtually devoid of
moisture, causing an arid climate on the leeward
side of the mountain.
Rain shadow
effect
Windward side –
receives rain
• Responsible for
impressive forests
– Olympic rainforest
on Washington state’s
coast (receives 5m of
rain per year)
Leeward side –
extremely dry
• Causes the severest
deserts in the world
– Death Valley in
eastern California
Coriolis Effect
• The deflection of an object above the Earth
including wind currents.
– Southern Hemisphere
• Left
• East
• clockwise
– Northern Hemisphere
• right
• west
• Counterclockwise
Coriolis Effect
• The Earth is a spinning
globe where a point at the
equator is traveling at
around 1100 km/hour, but
a point at the poles is not
moved by the rotation.
• This fact means that
projectiles moving across
the Earth's surface are
subject to Coriolis forces
that cause apparent
deflection of the motion.
The Coriolis Effect determines the direction
of major Wind Patterns
1. Trade winds
• between 30° N and equator; 30°S and equator
• Named for the ability to propel trading ships across the ocean
• Move counterclockwise (right) in Northern hemisphere; clockwise
(left) in Southern hemisphere
2. Westerlies
• Between 30° N and 60° N; 30° S and 60° S
• Travel south and west in Northern hemisphere; north to west in
Southern hemisphere
3. Polar easterlies
• Between 60° N and North Pole; blow north to east
• Between 60° S and South Pole; blow south to east
Prevailing Wind Patterns
Ocean Currents
• The ocean currents mirror the movements of the
atmosphere flowing clockwise in the Northern
hemisphere and counterclockwise in the
Southern hemisphere.
• Warm equatorial waters flow (set in motion by
prevailing winds and the rotation of the Earth) to
the poles and cold polar water flows toward the
equator setting up circular patterns known as
gyres.
• This massive movement of ocean water plays an
important role in determining the Earth’s climate.
Global Heat Engine
The major role of
the gyres is to
redistribute heat
from the equator
to the Northern
latitudes thus
regulating Earth’s
climate.
El Nino and Southern Oscillation
(ENSO)
•
•
•
•
Occurs in the Tropical Pacific Ocean
Natural climate variation
Causes fish populations to decline
The trade winds weaken, allowing warm water
to move eastward
• Upwelling is suppressed off the coast of South
America
– Upwelling – area of cool, high-nutrient waters
along a coast.
La Nina
(ENSO)
• The reverse of El Nino
• Surface water of the ocean surrounding
Central and South America are colder than
normal
• Fish populations and fishing industry thrive
due to prominent upwelling
• ENSO (El Nino and Southern Oscillation) – the
alteration of atmospheric conditions that lead
to El Ninos and La Ninas
Terrestrial biomes
• Classified based on 3 factors
1) Average annual temperature
2) Average annual precipitation
3) Distinctive plants adapted to the area - climax
vegetation
Classification by Name
•
•
•
•
•
•
•
More Narrow (7)
Rainforest
Temperate forest
Grassland
Desert
Taiga (Boreal forest;
Coniferous forest)
Tundra
Chaparral
Broad (4)
• Mountains
• Forests
• Grasslands
• Deserts
Latitude and Altitude
also determine biome characteristics
Deserts
….. At different
latitudes
Grasslands
•
•
•
•
•
•
•
•
Grassland
Savanna
Pampas
Prairie
Tundra
Steppes
Velds
Plains
Limiting Factors
• Temperate forests
• Space
• Seasonal variations
• Tropical Rainforest
• Space
• Nutrient-poor soil
• Grasslands
• Frequent fires
• Strong winds
• Low amount of precipitation (too dry to support trees)
Limiting Factors (cont.)
• Tiaga (Boreal/Coniferous Forest)
•
•
•
•
Cold temps
Low amount of precipitation
Decomposition rate very slow
Acidic; nutrient-poor soil
• Tundra
•
•
•
•
•
•
Cold temps
Low amounts of precipitation
Decomposition rate very slow
Short growing season
Few plants
High winds
Limiting Factors (cont.)
• Chaparral
•
•
•
•
Frequent fires
Drought
High temps
Low precipitation
• Desert
•
•
•
•
High temps
Very low precipitation
Brief sporadic growing season
Few plants
Adaptations - Plants
• Temperate forest
• Drop leaves in the fall
• Shade-tolerant due to vertical stratification
• Tropical rainforest
•
•
•
•
Shade-tolerant
Shallow roots
Enlarged roots (buttresses)
Take in water and minerals directly from rain
• Grasslands
• Extensive root systems ( several meters underground)
• Underground stems (to survive fires)
Adaptations – Plants (cont.)
• Taiga
• Needle-like leaves (drought resistant)
• Sloped branches (for snow to slide from)
• Tundra
• Shallow roots
• Small and short
Adaptations – Plants (cont.)
• Chaparral –
•
•
•
•
•
Extensive, shallow root system
Small, hard leaves
Allelopathic
Dormant during dry season
Fire-resistant roots
• Desert –
•
•
•
•
•
Extensive root systems
Store water (succelents)
Modified leaves (spines, thick cuticles)
Remain dormant for long periods of time (30 years)
Germinate very quickly
Adaptations - Animals
• Temperate forest –
• Hibernate
• Migrate
• Tropical rainforest –
• Live in trees
• Grassland –
• Live underground
• Migrate
Adaptations – Animals (cont.)
• Taiga –
• Hibernate
• Migrate
• Store body fat
• Tundra –
• Heavy fur coats
• White coats blend in with snow
• Specialized hooves, feet
Adaptations – Animals (cont.)
• Chaparral – animals are grassland/desert type
• Nocturnal
• Oversized ears
• Water-tight skin
• Desert –
•
•
•
•
•
•
•
Nocturnal; active in early morning
Burrow underground
Oversized ears
Pant or sweat
Water-tight skin
Get water from food they eat
Excrete highly concentrated urine
Forest Biomes
• 30% of the land area of the world is forest.
• Forests provide the following ecological
services:
– Conservation of biodiversity
– Moderation of climate
– Prevention of erosion
– Storage of carbon and nutrients
– Replenishing oxygen
Consequences of Deforestation
• One of the greatest threats to these biomes is
deforestation due to the conversion of forests
into pastures or agricultural fields.
– Reduces biodiversity
– Reduces nutrient availability
– Increases erosion
– Increases runoff and flooding
– Reduces the amount of CO2 removed from
atmosphere
5 Forest Management Methods
1. Clear-cutting – removing all trees in an area at one
time; leaves barren landscape.
2. Selective cutting – removing only certain trees;
maintains high biodiversity.
3. Shelter-wood cutting – removing mature trees in
groups over many years and leaving many trees to
reseed the area.
4. Seed-tree cutting – removing all small trees and
leaving the large, mature, seed-bearing trees.
5. Tree farms (plantations) – tracts of trees of the same
age that are planted and managed and harvested for
commercial use; little diversity.
Other Important Vocabulary
• Microclimate – small areas within a
biome/ecosystem that may have different
conditions than the biome itself.
– Caves, valleys, large forests, even cities
• Ecotone – a transitional area between two
biomes that has characteristics of both.
• Mitigation banking – creating or restoring as
much wetlands as are destroyed.
Transition Zones
Transition Zones
• Estuaries – areas where the mouth of a river
meets the sea; have high concentrations of
nutrients and sediments; rich in biodiversity.
– Chesapeake Bay, MD
• Mangrove swamps – coastal wetlands found in
tropical and subtropical regions.
• Barrier islands – created by the buildup of
deposited sediments just off the coastal shores;
act as buffers against storms. Erosion during
strong storms may erode islands completely;
prime land for tourism.
– Outer Banks, NC
Mangrove Swamps
•
•
•
•
•
•
•
Mangroves are salttolerant trees.
Trees protect the coast
from erosion and shield
inland area from severe
damage during
hurricanes and tidal
waves.
Traps sediment washed
off the land.
Act as “sponges” for
pollutants.
High in nutrients and
biodiversity.
Serves as sanctuary and
nursery for numerous
aquatic species.
Being cut down for
wood, shrimp farming
and coastal land
development.
AQUATIC LIFE ZONES
Freshwater Life Zones
Freshwater Life Zones
• Littoral zone – begins with very shallow water at
the shoreline, ends at depth at which rooted
plants stop growing; receives abundant sunlight;
nutrient-rich.
• Limnetic zone – surface of the open water area,
extends to the depth that sunlight can penetrate.
• Profundal zone – water that is too deep for
sunlight to penetrate; cool and dark; also known
as aphotic zone.
• Benthic zone – deepest layer in a body of water;
characterized by very low temperatures and low
oxygen levels. Decomposers are abundant.
The World’s Ocean
Oceans are divided into zones based on
changes in light and temperature and
cover about 70% of the earth’s surface.
Ocean Zones
• Coastal zone – consists of area between the shore and the
end of the continental shelf. Coral reefs are included in this
zone; has world’s highest NPP per unit area.
• Euphotic zone – includes the upper layers of water which
receive enough sunlight for photosynthesis to occur; is the
warmest region of the ocean and has the highest levels of
dissolved oxygen.
• Bathyal zone – steep descent of the seabed from the
continental shelf to the abyss; the middle region. Receives
insufficient light for photosynthesis and is much cooler.
• Abyssal zone – deepest region of the ocean; hydrothermal
vents located here.
Coral Reefs
• One of the most diverse ecosystems in
the world.
• Corals are animals that have algae
living in their tissues (zooxanthellae)
that allows them to photosynthesize.
• Require water that is clear, warm and
shallow enough for photosynthesis.
• Corals are extremely delicate and very
vulnerable to physical stresses,
changes in light intensity and water
temperature.
• Coral bleaching – when corals lose
their algae and turn white; due to
increased water temps (El Nino, global
warming).
• Sediments from construction and
agricultural practices are also
detrimental.
• Other threats include ecotourism,
collectors, exotic pet trade, and the
use of dynamite or cyanide to stun
fish.
The Abyss
• Zone marked by
extremely cold
temperatures and very
low dissolved oxygen
levels.
• High levels of nutrients
because of the decaying
plant and animal matter
that sinks down from the
zones above.
• Decomposers are mainly
bacteria.
• Organisms in this zone
often rely on
chemosynthesis to
survive.
Hydrothermal Vents
Primary Productivity
Human Impact
• Worldwide, about one billion people depend
on fish as their main source of food, and
about one million people are currently
employed in the fishing industry.
• About 125 million tons of fish are harvested
each year.
Fishing Methods
• Bottom trawling – technique in which the ocean floor is literally
scraped by heavy nets that smash everything in their path. Some
bans have been placed on this practice.
• Driftnets – nets that are dragged through the water and
indiscriminately catch everything in their path.
• Long lining – use of long lines that have baited hooks; taken by
numerous aquatic organisms.
• By-catch – term for any other species of fish, mammals, or birds
which are caught and are not the target species.
– Dolphins in tuna nets
Fish farming
in cage
Trawl flap
Trawler
fishing
Spotter airplane
Sonar
Purse-seine fishing
Trawl
lines
Trawl bag
Long line
fishing
Fish
school
Drift-net fishing
Float Buoy
Lines with
hooks
Deep sea
aquaculture cage
Fish caught
by gills
Fig. 12-A, p. 255
Tragedy in the Commons
• Occurs when a resource utilized by many people
(the public) is exploited and eventually depleted.
• Many marine fisheries are being overfished.
According to the U.N.’s Food and Agricultural
Organization (FAO),
– 52% of fish stocks are fully exploited
– 16% are over-exploited
– 8% are depleted
Solutions to the Tragedy
• Private ownership
– The assumption is that if you own the resource,
you will take better care of it.
• Regulation
– Establish laws that prevent tragedy from
occurring. For example, put limits on how many
fish can be caught per company per season.
US Laws
Name of Legislation
1. Anadromous Fish
Conservation Act (1965)
2. Magnuson Fishery
Conservation and
Management Act (1976)
3. Marine Mammal Protection
Act (1972)
4. Endangered Species Act
(1973)
1.
2.
3.
4.
What it Does
Protects fish that live in the sea
but grow up and breed in
freshwater (salmon)
Governs the conservation and
management of ocean fishing
Established a federal
responsibility to conserve
marine mammals (manatee)
Provides broad protection for
species of fish, wildlife, and
plants that are listed as
threatened in the US or
elsewhere
International Treaties
Name of Legislation
1. The United Nations
Agreement for the
Implementation of the
Provisions of the United
Nations Convention of the
Law of the Sea (1982)
2. CITES (1975)
The Convention on International
Trade in Endangered Species of
Wild Fauna and Flora
What it Does
1. Sets out the principles for
the conservation and
management of certain
types of fish
2. An international agreement
between governments that
ensure that international
trade in specimens of wild
animals and plants do not
threaten their survival
Aquaculture
• The practice of growing fish and other aquatic
organisms in captivity for harvest; mostly
salmon and shrimp.
• The hope is that this fishing method will help
to eliminate poverty and improve the lives of
people by allowing them to produce valuable
food.
Aquaculture – Environmental Concerns
• Tanks or cages in which these captive fish are
raised allows for the build up of
concentrations of wastes which pollute the
water.
• The accidental release of farmed fish into the
wild could introduce new diseases to ocean
fish and contaminate the native gene pool,
thus weakening the wild species.