Transcript Garrison Oceanography 7e Chapter 1

Oceanography
An Invitation to Marine Science, 7th
Tom Garrison
Chapter 1
Origins
1-1: Earth Is an Ocean World
• Most of Earth’s surface is
covered by a liquid-water
ocean averaging 3,796 meters
(12,451 feet) deep.
• Ocean: Vast body of saline
water that occupies the
depressions of Earth’s
surface.
1-1: Earth Is an Ocean World
Benefits of the ocean:
• A liquid-water ocean moderates temperature
• Dramatically influences weather
• Nurtures life
• Provides crucial natural resources
– 2% of world’s food.
– 1/3 of world’s oil and natural gas
1-1: Earth Is an Ocean World
• More than 97% of the water lies in the ocean.
• Less than 3% is in land ice, groundwater, and
freshwater lakes and rivers.
1-2: Marine Scientists Use the Logic of
Science to Study the Ocean
• Marine Science (oceanography): process of
discovering unifying principles in data obtained from
the ocean.
• Interdisciplinary:
– “inter” = between
– “between disciplines” = integrates many different
types of science
1-2: Marine Scientists Use the Logic of
Science to Study the Ocean
• Marine geology = “earth” “the study of”
– Study Earth’s crust and composition.
• Marine biology = “life” “the study of”
– Study the nature and distribution of marine organisms.
• Physical oceanographers
– Study of waves, currents, and climate prediction.
• Chemical Oceanographers
– Study the ocean’s dissolved gases and solids in the ocean.
• Climate Specialists
– Investigate the ocean’s role in Earth’s changing climate.
• Marine engineers
– Design and construct structures used in or on the ocean.
1-2: Marine Scientists Use the Logic of
Science to Study the Ocean
Oceanographers deploy a mooring containing temperature
probes from the deck of R/V Oceanus during a gale off
Cape Hatteras.
1-2: Marine Scientists Use the Logic of
Science to Study the Ocean
• Science: systematic process of asking
questions about the observable world by
gathering and studying information (data)
– Interprets raw information by constructing a
general explanation with which the information is
compatible.
1-2: Scientific Method – 5 Basic Steps
STEP 1: Identify the problem (or question) – based on
observations
– Scientists start with a question based upon something
observed or measured.
– Example: You are walking on the beach, you go out
on the pier… as you gaze into the water you notice a
lot of dead fish. What is you question based on the
observation?
• QUESTION:
1-2: Scientific Method – 5 Basic Steps
STEP 2: Make a hypothesis
• Working hypothesis: tentative explanation for the
observation or measurement that can be tested and
verified by further observations and controlled
experiments
– Educated guess that can be tested.
– “If, then” Statement
– EXAMPLE:
1-2: Scientific Method – 5 Basic Steps
STEP 3: Design an experiment to test hypothesis
• An experiment is a test that simplifies observation
in nature or in the laboratory by manipulating or
controlling the conditions under which the
observations are made.
• Control Group: The group that does not receive a treatment or
remains unchanged
• Independent Variable: The part of the experiment that is
changed.
• Dependent Variable: The variable that is measured or effected
by the independent variable.
– EXAMPLE: How would you set up the experiment?
1-2: Scientific Method – 5 Basic Steps
STEP 4: Interpret and analyze results –
• Data: any information acquired through observation
or experimentation.
– Organizing data into tables and graphic illustrations helps
scientists analyze and explain the data clearly to others.
– If the data support your hypothesis, you have a theory.
1-2: Marine Scientists Use the Logic of
Science to Study the Ocean
• Theory – a hypothesis consistently
supported by observation or experiment.
• Laws – larger constructs that summarize
experimental observations.
• A law summarizes observations while a
theory provides an explanation for the
observations.
1-2: Scientific Method – 5 Basic Steps
STEP 5: Report results, procedures, & conclusions
• Reporting results is important because it allows
other scientists to verify your work and
conclusions, and it allows other scientists to
build on what you’ve learned.
1-2: The Scientific Method
An outline of the scientific method, a systematic process of asking questions
about the observable world and then testing the answers to those questions.
1-2: Scientific Method:
Interpret and Analyze Results
• Statistics is the collection and classification of data that
are in the form of numbers.
• Scientists use statistics to describe statistical
populations.
• A statistical population is a group of similar things that
a scientist is interested in learning about.
– A sample is a representative population from the
statistical population.
1-2: Scientific Method:
Interpret and Analyze Results
Statistical population vs. sample size
Scientific Method:
Interpret and Analyze Results
• Average or Mean
• A mean is the number obtained by adding up the data
for a given characteristic and dividing this sum by the
number of individuals.
• The mean provides a single numerical measure for a
population and allows for easy comparison.
• Example: Average
temperatures in FL,
compared to rest
of United States.
Earth’s formation
•
•
•
•
•
Most atoms come from the explosion (death) of stars.
Our sun and planet arose from condensed dust.
The oceans formed from Earth’s escaped gases.
These are all theories since there is no direct proof.
Earth is believed to be 4.3 billion years old.
The Big Bang Theory
• The universe began with
the “big bang” 13.7
billion years ago.
• All of the condensed
matter in the universe
was concentrated in one
point and then exploded
outward.
• The expansion away from
the center continues
today.
• As it expands, it cools;
various atoms are
formed.
Galaxies,
Stars, and
Solar systems
•A galaxy is a huge rotating
mass of gas, dust, stars, and
planets held together by
gravity.
•Our galaxy is called the
Milky way.
•Stars are mostly made of
hydrogen & helium.
•Accretion- formation of
planets by the clumping of
smaller materials into larger
ones.
•Our sun and its planets
make up the solar system.
The life of a star
A Nebula (gas cloud) flattens and becomes a
Protostar .
Further shrinkage leads to a Star.
Towards the end of a star’s life it depletes its
supply of Hydrogen, heats up and explodes in
a Supernova.
This provides matter for new planets.
Accretion of planets
In perspective
•The universe contains perhaps 100 billion
galaxies, and 100 billion stars in each galaxy!
• Our sun and planets formed from the
condensation of solar gases.
•The inner planets are solid.
•The outer planets are gaseous.
Density Stratification
• Gravity pulls the heavier materials to the center, lighter
materials remain to the exterior.
• This is the idea behind density stratification.
• The atmosphere formed from the outgassing of Earth.
• Further cooling led to millions of years of rains.
• This led to the formation of the oceans.
Origin of life
• Life began in the ocean
from the building blocks
of life.
• Biosynthesis- the theory
that life arose from simple
organic molecules.
• Fossils found, suggest life
began over 3 billion years
ago.