Oceanography 6-9 review

What are tides?

Tides are the rhythmic rise and fall of sea level.

What type of waves are tides considered?

Very long and regular shallow-water waves.

What causes tides?

The gravitational attraction of the Sun, Moon, and Earth.

Do different tidal patterns exist around the world?

Yes, there are several different tidal patterns.

What causes the second tidal bulge on Earth?

The Earth is slightly pulled toward the Moon, creating a second bulge on the opposite side.

What are spring tides?

Tides that occur during new or full moons, when the tidal range is greatest.

When do neap tides occur?

During quarter moons.

What is the tidal range like during neap tides?

The tidal range is the least.

What is a diurnal tide?

One high tide and one low tide per day.

What is a semidiurnal tide?

Two high tides and two low tides per day, with about the same tidal range.

What is a mixed tide?

Two high tides and two low tides per day with different tidal ranges; the most common type of tide.

Where is the world's largest tidal range found?

The Bay of Fundy in Nova Scotia.

What is grunion spawning?

A reproductive event where small silvery fish come out of the water in California to spawn.

When do grunion spawn?

After each nights higher high tide has peaked, on the three or four nights following the highest spring high tide.

What are progressive waves?

Waves that oscillate uniformly and progress without breaking.

What are the two types of progressive waves?

Longitudinal and transverse waves.

What are longitudinal waves also called?

Push-pull waves.

How do longitudinal waves move particles?

By compressing and decompressing, like a coiled spring.

Through what mediums can longitudinal waves transmit energy?

Solids, liquids, or gases.

What are transverse waves also called?

Side-to-side waves.

How does energy travel in transverse waves?

At right angles to the direction of moving particles.

What medium can transverse waves generally transmit through?

Only solids.

How do wave particles move in circular orbital motion?

In circular paths as the wave passes.

What advances in circular orbital motion?

Wave energy.

What is the crest of a wave?

The highest point of the wave.

What is the trough of a wave?

The lowest point of the wave.

What is the still water level?

The zero energy level or calm sea level.

What is wave height (H)?

The vertical distance from crest to trough.

What is wavelength (L)?

The horizontal distance between two consecutive crests or troughs.

What are orbital waves also called?

Interface waves.

Where are orbital waves found?

On the ocean surface.

What three factors affect wave energy?

Wind speed, wind duration, and fetch (distance over which wind blows).

What is constructive interference?

When in-phase wave trains combine to produce larger waves.

What is destructive interference?

When out-of-phase wave trains cancel each other out.

What are the three types of breakers?

Spilling, plunging, and surging breakers.

What type of sea floor produces spilling breakers?

A gently sloping sea floor.

Describe spilling breakers.

Wave energy is expended over a long distance; water slides down the front slope.

What type of sea floor produces plunging breakers?

A moderately steep sea floor.

Describe plunging breakers.

Energy is released over a shorter distance; the crest curlsâ€"ideal for surfing.

What type of sea floor produces surging breakers?

A steep sea floor.

Describe surging breakers.

Energy released over a very short distance; waves break on shoreâ€"good for body surfing.

What causes tsunamis?

Sudden changes in sea floor topography such as earthquakes, landslides, volcanoes, or meteorite impacts.

What is the most common cause of a tsunami?

Underwater earthquakes.

What does PTWC stand for?

Pacific Tsunami Warning Center.

Where is the PTWC located?

Honolulu, Hawaii.

What does PTWC use to forecast tsunamis?

Seismic wave recordings.

What does DART stand for?

Deep Ocean Assessment and Reporting of Tsunami.

What does the DART system use?

Buoys that detect the pulse of passing tsunamis.

What is a Tsunami Watch?

Issued when there is potential for a tsunami.

What is a Tsunami Warning?

Issued when unusual wave activity is verified; people should evacuate and ships should leave harbors.

What are the two main types of ocean currents?

Surface currents and deep currents.

What drives surface currents?

Wind; they primarily move horizontally.

What drives deep currents?

Differences in density caused by variations in temperature and salinity.

What type of motion do deep currents have?

Both vertical and horizontal motions.

What is a gyre?

A large, circular loop of moving water.

Where are subtropical gyres centered?

Around 30 degrees latitude.

What are the four main boundaries of a subtropical gyre?

Equatorial, western boundary, northern/southern boundary, and eastern boundary currents.

Name the five major subtropical gyres.

North Atlantic (Columbus), South Atlantic (Navigator), North Pacific (Turtle), South Pacific (Heyerdahl), and Indian Ocean (Majid).

What direction do Northern or Southern Boundary Currents flow?

Easterly across the ocean basin.

Where are Eastern Boundary Currents found?

Along the eastern edges of ocean basins.

What are characteristics of Eastern Boundary Currents?

Cool, slow, shallow, and wide.

What are characteristics of Western Boundary Currents?

Warm, fast, narrow, and deep.

What causes western intensification?

The Coriolis effect.

What is the North Atlantic Subtropical Gyre composed of?

Florida Current, Gulf Stream, North Atlantic Current, Canary Current, and North Equatorial Current.

What is unique about the Gulf Stream?

It moves northward along the U.S. East Coast, meanders, merges with the Sargasso Sea, and supports Sargassum biology.

What are normal atmospheric-ocean conditions in the Pacific called?

Walker Circulation Cell (normal conditions).

During normal Pacific conditions, where is air pressure higher?

In the eastern Pacific.

During normal Pacific conditions, where is the thermocline deeper?

On the western side of the Pacific.

What is upwelling?

The upward movement of cold, nutrient-rich water from the deep ocean to the surface.

What happens during El Niño (ENSO warm phase)?

High pressure in the eastern Pacific weakens, trade winds weaken, warm water migrates east, downwelling occurs, and productivity decreases.

How does El Niño affect Peruvian fishing?

It decreases productivity and harms fishing.

What happens during La Niña (ENSO cool phase)?

Trade winds strengthen, upwelling increases, thermocline becomes shallower, water cools, and productivity rises.

What is thermohaline circulation?

Deep ocean circulation driven by temperature and salinity differences.

What percentage of ocean water is part of thermohaline circulation?

About 90%.

Where does thermohaline circulation occur?

Below the pycnocline.

What is the speed of deep-ocean currents?

They move very slowly.

What is the tilt of Earth's axis of rotation?

23.5 degrees with respect to the plane of the ecliptic.

What is the plane of the ecliptic?

The plane traced by Earth's orbit around the Sun.

What causes Earth's seasons?

The tilt of Earth's axis relative to its orbital plane.

What is the troposphere?

The lowest layer of the atmosphere where all weather occurs.

How high does the troposphere extend?

About 12 km (7 miles) above Earth's surface.

How does temperature change with altitude in the troposphere?

Temperature decreases with increasing altitude.

How does air flow in relation to pressure?

Air flows from high to low pressure.

What is wind?

Moving air caused by differences in atmospheric pressure.

Where is Earth's rotational velocity zero?

At the poles.

Where is Earth's rotational velocity greatest?

At the equator (over 1600 km/hour or 1000 miles/hour).

What is the Coriolis effect?

The apparent deflection of moving objects due to Earth's rotation.

Where is the Coriolis effect greatest?

At the poles.

Where is the Coriolis effect zero?

At the equator.

What are the three types of atmospheric circulation cells?

Hadley Cell, Ferrel Cell, and Polar Cell.

What latitudes define the Hadley Cell?

0â€"30 degrees latitude.

What latitudes define the Ferrel Cell?

30â€"60 degrees latitude.

What latitudes define the Polar Cell?

60â€"90 degrees latitude.

What causes high and low pressure zones on Earth?

Rising and descending air from global circulation cells.

What are trade winds?

Winds that blow from subtropical highs toward the equator.

Where are northeast trade winds found?

Between 0° and 30° North latitude.

Where are southeast trade winds found?

Between 0° and 30° South latitude.

Where are prevailing westerly wind belts located?

Between 30° and 60° north and south latitude.

Where are polar easterly wind belts located?

Between 60° and 90° north and south latitude.

What are tropical cyclones?

Large rotating masses of low pressure with strong winds and heavy rain.