Waves and Tides
Waves
Everyone has seen
waves on a lake or
ocean. But what are
they? Waves are
actually energy.
Energy, not water,
moves across the
ocean's surface.
http://www.virtualnjshore.com/tbwaves.html
Wavelength
Wave
Height
Crest
Still Water
Trough
Wave Parts
What causes waves?
Waves are caused by energy being transferred into
the ocean water
The energy come from:
1. Wind- the wind is air that moves by energy
from the sun.
2. Undersea Earthquakes- they can also put
energy into the water
What determines the size of a wave?
If waves carry energy, what has more energy, a big wave
or a small wave?
If winds cause waves, will stronger ,faster winds give wave
more or less energy? (activity)
If wind blows for a long time will the waves have more or
less energy?
If wind the wind blows over a small part of the ocean
what will happen to the wave’s energy?
-
-
The size of the wave depends on the amount of
energy transferred into the water.
The amount of energy depends on 3 things.
1. Speed of the wind
2. How long the wind blows
3. The distance over which it blows
If any of these increases, the size of the waves will
also increase
Why are waves
important
Storm Surge
A
storm surge is a rise in
sea level near the shore
It
is caused by strong
winds fro a storm like a
hurricane.
http://www2.sunysuffolk.edu/mandias/38hurricane/storm_surge_maps.html
Tsunami
A tsunami is a powerful
wave (or group of
powerful waves) cause by
the shaking of the ground
under oceans.
Earthquakes and
volcanoes can cause
tsunamis.
Effects of the Asian Tsunami
In 2004, an earthquake occurred under the Indian ocean.
Wrap-up and Exit Ticket
Word Bank:
Waves, wavelength, crest,
wave height, wave speed.
Consists of a
Trough
Whose size determines
and the distance between two
of these is the
Which is used to
calculate
Tides
A tide is a rise or fall of the ocean’s
surface
High tide in Nova Scotia
Low tide in Nova Scotia
Tides are caused mostly by the pull of gravity of the moon.
The sun’s gravity also affects a tide just not as much as the
moon’s
Why we study tides
Tides are important
- When building beach properties.
- Animals: Some animals like sea turtles only lay
their eggs on certain tides (page 368)
- Safety of humans
- For Energy: Scientists can use movement of
water during tides to produce energy (the
enegery of the water powers generators to
produce electricity)
Tides – how it works
The moon can add to the
pull of the sun and make
higher tides.
The moon can work
against some of the
gravitational pull of the
sun and make the tides
lower.
http://curious.astro.cornell.edu/images/tides.jpg
High Tides
High Tides occur when the oceans water has risen
as far as it will go
-This happens when the oceans on Earth are
facing the moon
Low Tide

When the ocean water has fallen as low as it can
go on shore

It happens when the moon is sideways from the
shore
Spring Tide

During this tide the sun, moon, and Earth are aligned
so gravity from the sun and moon pulls the oceans

This happens during a new moon or full moon.
Neap Tides


This is when the ocean levels on land are as low
as they can go.
It only happens during a First Quarter new and
a Last Quarter moon.
Tide Timing



The time between 2 high tides is 12 hours
The time between 2 low tides is 12 hours
There is a period of 6 hours between a high tide
and a low tide