Unit 1 Chapter 2 Oceans Control the Water Cycle

1
Unit 1 Chapter 2Oceans Control the Water Cycle

• Section 2.3 (Slide Show 6)
• Waves Tides

2
What is a Wave? (p.64)

• A wave can be described as a disturbance that
  travels through a medium from one location to
  another location.
• A medium is a substance or material which carries
  the wave such as water or a slinky.

3
Features of a Wave (p.65)

• The section of the wave that rises above sea
  level is called the crest or peak. That section
  which lies below sea level is called the trough.

4
Features of a Wave (p.65)

• The amplitude of a wave is the height of the
  wave. It is measured from sea level.

5
Features of a Wave (p.65)

• The wavelength of a wave is the distance between
  any two adjacent locations on the wave. This
  distance is usually measured in one of three
  ways
• crest to next crest,
• trough to next trough,
• from the start of a wave cycle to the next
  starting point

6
Features of a Wave (p.65)

• A common misconception about wave motion is that
  the water particles move with the waves.
• However, as you can see from the red dots, the
  water moves up and down in a circular pattern and
  then returns to its original position.

7
How Do Waves Move? (p.65)

• As we learned from the previous section, winds
  transfer their energy (through friction) to the
  water particles.
• Then, as the water particles move in a circular
  motion, they bump into each other and pass their
  energy along.
• This transfer of energy keeps the wave moving
  through the water.

8
Types of Waves (p.64-66)

• Swells
• Swells are smooth waves that steadily move across
  the water.
• These are caused by winds and storms far out in
  the ocean and so can occur even on a calm day.
• Its the swells of the ocean that often cause sea
  sickness!

9
Types of Waves (p.64-66)

• Breaking Waves
• When a wave reaches a shore or underwater rock,
  the wave collapses in a tumble of water called a
  breaker.
• This occurs because the trough of the wave slows
  down on the shore while the crest keeps moving.
  This shortens the wavelength but increases the
  amplitude of the wave.
• See the following animation.

10
Types of Waves (p.64-66)

• Tsunamis
• Tsunamis are giant waves caused by earthquakes,
  volcanic eruptions, or landslides along the ocean
  floor.
• These events give the ocean water a push
  creating wavelengths as large as 150km!!
• Given on the right shows the devastated shoreline
  at Port au Bras, Newfoundland, 1929.

11
Waves Erosion (p.66-69)

• Aliant Learning Center
• Video Summary
• Coastal Processes and Landforms

12
What is Erosion?

• Erosion is the wearing down and carrying away of
  rock material.
• The movement of water is one of the most powerful
  causes of erosion.
• The stronger and more powerful the water, the
  more erosion occurs.
• This is why the majority of erosion along
  coastlines occurs during storms a time when
  winds and waves are very strong.
• Another factor that affects erosion is the type
  of rock.
• Softer rocks such as shale or chaulk will erode
  quicker than harder rocks such as limestone.

13
How Waves Change Shorelines (p.66-68)

• The erosion of waves create many different
  shoreline structures
• Caves
• Waves eventually wear away rock forming hollows
  called caves.
• Sea Arch
• When caves wear completely through a rock, a sea
  arch or tunnel is formed.
• Stacks
• Overtime, the weight of the ceiling of the sea
  arch causes it to collapse, leaving a piece of
  rock separated from the land called a stack.

14
Coastline Structures from NL
15
Headlands Bays (p.67)

• The formation of sea caves, arches, and stacks
  occur from the erosion of headlands.
• The shorelines are composed of many different
  types of rock.
• Softer rock (such as sandstone) erode faster
  creating bays.
• Pieces of land composed of harder rock (such as
  limestone or granite) do not erode as quickly
  creating headlands.
• Since headlands reach farther out to sea, they
  receive the main force of the waves.
• This battering of waves creates interesting
  features such as sea caves, arches, and stacks.

16
Formation of Beaches (p.68-69)

• As waves erode the shorelines, the sediments get
  carried out to sea.
• Eventually, these sediments roll into bays where
  the waves have slowed down and have lost most of
  their energy.
• These sediments build up and, overtime, form a
  beach.

17
Tides (p.69-71)

• Aliant Learning Center
• Video Summary
• Cycles and Seasons

18
Gravity Tides (p.69-71)

• Tides are the rise and fall of the ocean caused
  by the gravitational pull of the sun and moon.
• On Earth, gravity is a force that pulls all
  objects towards the center of the Earth.
• The moon and sun also have gravity, and they too
  pull things to their center.
• Gravitys battle between the Earth, moon, and sun
  is what causes our tides.

19
Spring Neap Tides

• The largest tidal movements, called spring tides,
  occur when the Earth, the Moon, and the Sun are
  in a line.
• Tides are extra high and extra low at this time
  since both the Moons and Suns gravity are
  pulling on our oceans simultaneously.
• The smallest tidal movements, called neap tides,
  occur when the Sun and Moon are at right angles
  with each other.
• The tidal range (difference between high and low
  tide) is smaller at this time since the pull of
  the Moons gravity acts in a different direction
  than the pull of the Sun.

20
Spring Neap Tides
21
Spring Neap Tides
22
Section 2.3 Assignment

• Assignment 2 (Part 3)
• P.77 2, 3, 9, 10, 11, 13