Transcript Marine Biology

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Chapter 8
Michael Slemp
Octopus
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Is cephalopod mollusc
Octopuses have two eyes
8 arms with suction cups
Hard beak in the mouth
Octopuses have no internal or
external skeleton
One of the most intelligent
of all invertebrates
To defend themselves, they release ink (melanin = same as your hair and
eye color), use camouflage and arm autonomy (detaching of arm)
All octopuses are venomous
Short life expectancy (6months-5 years). Die shortly after reproduction
They have 3 hearts ( 2 pumps blood thru gills and 1 thru body)
They eat crabs, other molluscs (clams), fish, other cephalopods
What is AIR (atmosphere)?
Gases
Nitrogen 78 %
Oxygen 21 %
Argon 1%
Carbon Dioxide 0.03%
All other gasses 0.01%
See pie chart in your book
page 8-4
Water vapor
Water vapors are
invisible. The
reason clouds are
white is because
the water have
condensed
Aerosol
Aerosol is liquid
and solid
particles
suspended in
air (like dust,
pollen, ash)
Water vapor and aerosol
makes about 4% of air)
Atmospheric layers
Thermosphere: beyond
110,000 meters (360,800
feet) into space
Mesosphere: up to 100,000
meters (360,800 feet)
Stratosphere: up to 50,000
meters (164,000 feet)
Has the most ozone!
Troposphere: from sea level
up to 15,000 meters
(49,200 feet)
Contains most of the air. Air
compresses under its own weight =
higher air pressure
What is ozone?
• Gas composed of 3 oxygen atoms (O3)
• Normally oxygen molecule has 2 oxygen
atoms (O2)
• Extra oxygen in ozone causes instability
and increased reactivity
• Ozone is mostly in stratosphere and
absorbs the UV light (radiation from sun)
• Ozone protect us. If there would be no
ozone, the UV light would kill the life on
our planet
• In 1974, scientist came out with theory
that ozone interacts with CFCs (chemical
found in aerosols and air conditions)
• Reaction of ozone with CFCs can cause
ozone hole and effect life on planet Earth!
Scientists are monitoring the
size of the ozone hole
existing over Antarctica
How much water vapor is in the air?
That depends on temperature, density and pressure
As temperature increases, pressure increases and density decreases
• Adding water
vapor decreases
air density even
more
• Air is denser than
water vapors
• Warm, moist air is
less dense than
cold air.
• Two air masses of
the same
temperature can
have different
densities
• It depends on the
amount of water
vapor
• Air with more water
vapor is less dense
Evaporation
Adds water vapors
into the air
Condensation
Removes water
vapors from the air
Saturated air
Air in which the rate of
evaporation and the rate of
condensation are the same.
The amount of water vapors
is unchanged.
What happens when
saturated air warms up?
• It becomes
undersaturated.
• Evaporation adds more
water vapors into
undersaturated air.
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What happens when saturated air cools
down?
There is increased condensation
Water vapors are removed from air in
form of rain or snow (if temperature is low
enough)
Initially water droplets or ice crystals are
very small and remain suspended in air
As they collide, they form bigger drops or
clusters or ice crystals. This lead to rain or
snow
Rain and snow happens when warm moist
air mass collide with cooler air mass
Why is this important?
• Air movements redistribute heat around the Earth
• Precipitation is our main source of fresh water
• All underground water, rivers, lakes get their water from rain and
snow. They return water and nutrients back to the ocean
Earth’s heat balance
Sun is the
major energy
source for
Earth’s surface
25%
20% absorbed
by clouds and
atmosphere
5%
20%
Atmosphere either
absorbs or reflects
45% of sunlight
55% of sun’s
energy reaches
Earth’s surface
25% reflected
by clouds and
atmosphere
50% is absorbed
by Earth’s surface
50%
5% is reflected by
Earth’s surface
Earth’s heat balance
At any time, only half
of the Earth’s surface
receives sunlight
(makes day and night)
The energy coming to
earth is ultimately lost
as heat radiating back
into space
What is solar energy?
Visible light
Makes it through
the atmosphere
to Earth with
little absorption
UV light
(ultraviolet light)
Is absorbed
mostly in
stratosphere by
the ozone layer
Infrared light
Some is absorbed
by carbon dioxide
and water in
stratosphere and
troposphere
Earth’s heat balance
Solar Energy is reflected from
various surfaces like
• clouds
• atmospheric particles
• snow
• reflective objects on Earth’s
surface
ALBEDO
• The measure of amount of
energy something reflects
• Snow has high albedo
• Black sand has low albedo
To maintain balance between
incoming energy from sun,
eventually all energy Earth absorbs
reradiates through various paths
back to space as infrared radiation
Unbalanced energy =
Earth gets hotter, less
likely we survive!
Yellow = reflection, red = absorption
Left arrow – snow, right arrow -water
Greenhouse effect
• Important for life on Earth
• Atmosphere, after it absorbed
infrared radiation, reradiates
a lot of the heat back to
Earth’s surface
• Most of the heat is collected in
troposphere and stratosphere
layers
• Without Greenhouse effect
Earth would be on average
35°C (95°F)
The concern is that increased carbon dioxide and other heat-retaining gasses
will cause global warming and increase the overall temperature on Earth!
Uneven Heating
• If there would be even heating on earth, there would be little
changes in temperature and no seasons
• But we know that there are seasons and temperature changes
• There are 3 primary factors that cause the Earth to heat unevenly:
1. Earth is spherical
2. Earth’s axis of rotation is tilted
3. Distance between Earth and sun varies with the time of the
year
Uneven Heating
In order to be perpendicular rays, they
would have to come from this direction,
which does not happen in this area!
1. Earth is spherical
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Small part of sphere receives
perpendicular light rays (mainly in
areas around equator)
Most of the sphere receives slanted
light rays
These slanted rays have same energy
but got to cover larger area (means less
energy per area unit)
The farther North and South you go,
the more slanted the sunlight reaching
the surface
Slanted rays
Perpendicular rays
Uneven Heating
2. Earth’s axis of rotation is tilted
• Earth does not spin with its axis perpendicular
to the plane of its orbit
• Earth’s orbit inclines 23.5 degrees off
• Equator does not always receives perpendicular rays from the sun
• Depending on the time of the year, perpendicular sun rays fall
anywhere between the Tropic of Cancer (23.5° north latitude) and
Tropic of Capricorn (23.5° south latitude)
• Longest day of the year for each hemisphere is when the sun is
directly overhead at the Tropic line
Uneven Heating
2. Earth’s axis of rotation is tilted
• The Amount of sunlight falling on
different parts of Earth changes
and creates seasons
• When the Earth is tilted with
North Pole toward the sun = there
is summer in North hemisphere
(and winter in South hemisphere)
• When the Earth is tilted with
North Pole away from the sun =
there is winter in North
hemisphere (and summer in South
hemisphere)
Uneven Heating
3. Earth’s orbit is not circular
• Earth’s orbit is slightly elliptical
• Earth gets more heat when its orbit brings it closer to the sun
• Earth is closer to the sun during winter in North hemisphere and farther
away from the sun during summer in North hemisphere
• This explains why North hemisphere has warmer winters and cooler
summers than South hemisphere
Uneven Heating
Biological Importance
• Based on seasons we can predict
migratory patterns
• Gray whales annually migrate to
Arctic waters to feed off
blooming krill and plankton in
summer
• In winter gray whales swim south
to breed in warmer waters
around the Mexican Baja
Peninsula
Uneven Heating
Convection
• Convection is vertical movement of
currents caused by temperature
differences in a fluid (like air)
• On Earth, equator is the “kitchen
stove” warming up all the Earth’s
air and the poles are the cold parts.
• Equator: air heats up and rises,
travels towards the poles
• Poles: Air cools down and sinks, and
moves back towards equator where
it replaces warm air
• Solar energy absorbed by Earth
surface causes a general global
pattern of winds moving air
between equator and poles
Sun warms up Earth
Earth warms up air in contact with it
Warm air is less dense and raises
High above, warm air cools down
and becomes denser (moves down
towards the Earth surface)
• Cold air replaces warm air (and
cycle continues creating circular
pattern)
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Coriolis effect
Is the tendency for the path of a moving object
to deflect
• To the right on the Northern hemisphere
• To the left on the Southern hemisphere
Coriolis effect
• Explains why we have winds in all directions, not just from north or south
• Effects also the ocean currents
• Is major factor affecting the distribution of the Earth’s heat, nutrients and
many types of life
• Is caused by Earth’s rotation
• Is greater at higher latitudes
• Is zero at equator because the rotational velocity does not change
The wind
Recall
• Convection causes general circulation pattern that moves air between the
equator and the poles
• The Coriolis effect deflect air to the right as it travels (to the left in the
southern hemisphere)
• This gives the air circular flow pattern rather than a straight north-south
pattern
• It is not as simple as above!
• Wind patterns exists in small regions called atmospheric circulation cells
• Atmospheric circulation cells are six distinct air masses (3 in each
hemisphere) with individual airflow patterns
The wind – 1. Hadley cells
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Most important atmospheric circulation cell
They lie between the equator and 30
degree north or south latitude
Warm air rises at the equator and moves
northward due to convection
Air does not make it all the way to the north
pole
By the time it reaches 30°N it becomes dense
enough from cooling and moisture loss to
sink
Most of the air descends and flows back to
the equator, deflecting to the right
(westward) as it flows
This causes trade winds (flow westward
between equator and 30° latitude
Trade winds are what brought ships to Europe
and America centuries ago
The wind – 2. Ferrel cells
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Between approximately 30-60 degree
latitude
These cells exist because some of the
wind that descends from Hadley cells
does not turn toward the equator
They continue towards the poles shifting
to the right or left (depends on the
hemisphere)
The airflow forms the westerlies
(because they are from the west) and
blows towards the east
The vertical circulation in Ferrel cells is
opposite of what you would expect from
convention because it is “sandwiched”
between the Hadley cells and the Polar
cells
The wind – 3.Polar cells
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These lie between approximately 60
degrees and the pole
Airflow in the polar cell is similar to the
Hadley cell
Warm air at 60 degree rises and flows
towards the pole, where it cools,
descends, and flows back to the equator
Coriolis effect deflects it, so that the
prevailing polar winds go to the west
The south –flowing cold air from the
polar cells affects the air flowing north
and eastward in the Ferrell cells.
Two air masses do not easily mix due to
the different densities and
temperatures.
Polar cell air rises and heads northward
again from convection, and causes the
Ferrell cell air to deflect upward
INTERTROPICAL CONVERGENCE ZONES
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This is where the trade winds meet from both hemispheres
30 degrees north and south latitude
Trade winds rise in this region
Vertical movement of air in ITCZ transports large amounts of heat and
moisture
Water vapor condenses in the rising and cooling air, and rainstorms form.
Some of the world’s wettest climates are in the ITCZ
Surface winds are weak
Sailors call this area doldrums because they could be stranded there
without winds
ITCZ influences climates and weather, and the seasons and landmasses
affect the ITCZ
INTERTROPICAL CONVERGENCE ZONES
• This is the reason why there is a difference between the geographical
equator and the meteorological equator (ITCZ)
• Geographical equator is 0 degrees latitude
• ITCZ is an imaginary line marking the temperature equilibriums between
the hemispheres that shift North and south with seasonal changes.
• It shifts because land has lower heat capacity than water, and there is more
land mass in the northern hemisphere.
• Not a straight line due to the landmass affects its location
• The ITCZ equator is important because atmospheric circulation is
approximate symmetrical on either side of it
• 30 degree latitude leads to high evaporation and little rain fall
• Most of the earth’s desert are at this latitude
• There is a higher salinity around 30 degree latitude
• More water is evaporated that returns to the
ocean making a higher salinity concentration
Monsoons
• Seasonal wind pattern changes caused
by heating or cooling on the
continents
• Causes summers with significant
rainfall and winters with very little
• Results when air warmed by a hot
landmass rises
• Warm, moist air from the ocean flows
in to replace it; this in turns also rise
• Cools, which causes rain
• When winter comes the cycle is
reversed
• Wind reverses and land has very little
rain
• Common in India and southeast Asia
Cyclones
• Large rotation storm systems of low pressure air with
converging wind at the center
• Also called typhoon or hurricanes
• Two types: extra tropical and tropical
Cyclones - Tropical
• From within a single atmospheric cell
• Form in low latitudes
• Experience explosive growth because of
extremely rapid transport of heat and
moisture into the atmosphere from the
surface of the warm, tropical ocean
• They quickly dissipate once they hit land
due to the loss of heat
• Cyclones move tremendous amounts of heat from the tropics to higher
latitudes very quickly
• One cyclone can release about as much energy as the USA uses in an entire
year
• This redistribution of heat is important to life on earth
Cyclones - Extratropical
Form in higher latitude
Forms as an area of low air pressure intensifies
Occurs between the westbound polar winds and eastbound westerlies
These do not become hurricanes or typhoons
They do cause hurricane strength winds, huge ocean waves rain and
snow outside the tropics