Transcript Tides

Tides
tida_NOAA.gif
Purpose:
Explain tides and the relationship
with the Earth, Sun and Moon
Classify different types of tides
Identify hazards associated with tides
New Terms
Tides
 Tidal range
 Spring tides
 Neap tides
 Storm surge

Ocean Tides

The daily movement of ocean water that
changes the level of the ocean’s surface
Tides are caused by
1.The gravitational attraction
of the moon
2. “centrifugal force” as
Earth and the moon orbit
around a common center of
balance
The Earth and Moon orbit around the
“barycenter” (demonstration)
High Tides are bulges of ocean
water that occur on the side of the
Earth facing the moon and on the
side opposite
Low Tides are the areas between the
bulges. Tides change as the Earth
rotates between the bulges
Tides occur 50 minutes later each
day.

Since the moon moves along in its orbit
around the earth each day, the earth must
rotate an additional 50 minutes to catch up.
Spring Tides


Have a very large tidal range
Occur every 14 days during a full or new moon
Sun
Spring Tides
Sun
Moon
Moon
 Are
caused by the gravitational forces
of the sun and moon pulling in the
same directions (180 degrees)
Neap Tides
Have small tidal ranges between high and
low tides
 Occur every 14 days during 1st and 3rd
quarter moons

Neap Tides PHASESofMoon.JPG
Sun
Sun
Moon

Moon
Are caused by the gravitational forces of the sun
and moon pulling at 90 degrees from each other
Tidal Range is the difference in height
between the high tide and low tide.
At low tide in the Bay of Fundy, boats
can be left setting on the bay bottom.
High tide arrives in 30 minutes in the
Bay of Fundy, rising 20-50 feet
Tides of Nova Scotia
The Bay of Fundy is in Canada near
northeastern USA
The Bay of Fundy is known for tidal
bores. A tidal bore is the “face’ or edge
of the incoming tide and travels about 13
mph.
Surfing a tidal Bore
"
When hurricanes or winter storms arrive
during high tide, greater damage occurs.
Storm surges result when strong winds pile water
along the shoreline.
Storm surges may raise sea level up
to 18 feet above normal.
During Hurricane Andrew, an oceangoing tugboat was left high and dry
by storm surge.
Along the Florida Keys, houses are built
on stilts as a protection from storm
surges.