Oceanography - Unit 6

Mrs. Miller Best Study Guide

What causes ocean waves?

Energy passing through water, moving it in a circular motion.

What are three common forces that generate waves?

Wind, Geological events (e.g., earthquakes, landslides), Gravitational pull from the moon.

What is a tsunami?

A large wave caused by underwater earthquakes or volcanic eruptions.

What factors influence wave formation?

Wind speed, wind duration, water depth, and fetch.

What is fetch?

The distance over open water that wind blows.

What are the two main measurements used to describe waves?

Wave height and wave length.

What is the highest point of a wave called?

The crest.

What happens to wave speed in shallow-water waves?

It depends on the depth of the water.

What is longshore transport?

The movement of sand and sediment along the beach due to wave action.

What are the two restoring forces that dissipate wave energy?

Surface tension and gravity.

What is wave amplitude?

The vertical distance from the crest to the still-water level; equal to half the wave height.

What is the still-water level?

The water level when the surface is flat and smooth with no waves.

How is wave speed calculated?

Wave speed = Wavelength ÷ Period.

What does wave period measure?

The time it takes for one complete wave to pass a fixed point.

What is the formula for wave period?

Period (T) = 1 ÷ Frequency (F).

How do you calculate wave frequency?

Frequency (F) = 1 ÷ Period (T).

What does a surf report describe?

Wave size, consistency, wind, tides, and future wave conditions.

Why are tides included in surf reports?

Because they affect the shape and location of waves.

What does wave direction indicate?

The compass heading or directional path of wave movement.

How do you find the period of a wave with a speed of 6 m/s and a wavelength of 12 m?

Divide 12 m by 6 m/s to get a period of 2 seconds.

What is a tide?

Rise and fall of sea levels.

What causes tides?

Gravity from Moon and Sun.

Why two tidal bulges?

Gravity and centrifugal force.

Tidal cycle length?

24 hours, 50 minutes.

Moon vs. Sun’s pull?

Moon’s pull is stronger.

What affects tides?

Land and seafloor features

Why tides vary?

Geography, orbits, and weather.

What are spring tides?

Sun and Moon aligned.

What are neap tides?

Sun and Moon at angles.

Three tidal patterns?

Semidiurnal, mixed, diurnal.(Be able to visualize them)

High and low water?

Highest and lowest tide points.

Flood and ebb tides?

Water rises and recedes.

What is slack water?

Still water between tides.

What is tidal range?

Difference between high and low.

What is a tidal bore?

Fast tide wave in rivers.

What is a tsunami?

A huge wave that rises like a fast-moving tide.

What does “tsunami” mean in Japanese?

Harbor wave.

What causes most tsunamis?

Undersea earthquakes.

What other events can cause tsunamis?

Landslides or meteorite impacts.

Why are tsunamis hard to detect at sea?

They have small wave heights and long wavelengths.

How fast can tsunamis travel?

Up to 800 km/h (500 mph).

What happens when a tsunami reaches shore?

It slows, rises, and becomes a massive wave.

What happened in Lisbon in 1755?

A tsunami trough hit first; people drowned when the crest followed.

Why is the Pacific coast of North America at risk?

It lies on the Pacific Ring of Fire.

What helps warn people about tsunamis today?

Tsunami warning systems.