Download - NOTES What are the tides?
NOTES
What are the tides?
TURN TO PAGEpage 434-438 IN YOUR
SCIENCE BOOK
By: Mr. D'Angelone 2
Learning Objective
• Students will describe what causes and affects the tides.
By: Mr. D'Angelone 3
Key Terms
•tide•Spring Tides•Neap Tides
By: Mr. D'Angelone 4
Ocean Water Levels
• The water level of the ocean rises and falls throughout the day.
• Early in the day, ocean water rises and covers part of the beach.
• Later in the day, the ocean level falls. • The beach is exposed. • These regular changes in ocean water levels are
called tides. • A low water level is called low tide. • A high water level is called high tide.
By: Mr. D'Angelone 5
• Once a month we have a lower than normal Low tide (above) and a higher than normal high tide (below) in the same location.
By: Mr. D'Angelone 6
Causes of Tides
• The Earth's gravitational pull on the Moon keeps the Moon in orbit around us.
• The Moon also pulls back on Earth and causes the tides.
By: Mr. D'Angelone 7
Causes of Tides
• The Sun's gravitational pull also affects Earth's tides, but because it is so far away from us, not as strongly.
By: Mr. D'Angelone 8
Causes of Tides (2)
• Earth's continents are slightly stretched by the pull of the Moon.
• Earth's oceans, which move more freely, are stretched even more.
• This stretching effect creates two bulges of water on Earth, one facing the Moon, the other directly opposite it.
• These bulges are the high tides. • The bulging water also causes two areas with
low tides between the high tides. • As the Earth turns on its axis, the tide levels rise
and fall.
By: Mr. D'Angelone 9
• The Moon, along with the Sun, causes the tides. • Whether it is high tide or low tide depends
mostly on where you are on Earth relative to the Moon.
By: Mr. D'Angelone 10
Changing Tides
• Some newspapers print tide tables.
• A tide table tells the times at which high tide and low tide will occur.
• If you look at a tide table, you will notice that it often shows two high tides and two low tides each day.
• The tides change about every 6 hours and 15 minutes.
By: Mr. D'Angelone 11
Tide Table
A newspaper gives the times for high and low tide.
By: Mr. D'Angelone 12
Spring Tide
• A new moon phase and a full moon phase causes a major change in tides.
• This causes the Earth, moon, and sun to align which causes a very high tide called a Spring Tide. (2 spring tides per month)
By: Mr. D'Angelone 13
Neap Tide• A 1st quarter and a third quarter
moon phase causes a major change in tides.
• This causes the Earth and moon to be at a right angle to each other which causes a extremely low tide called a Neap Tide. (2 spring tides per month)
By: Mr. D'Angelone 14
Checking Concepts
• What is the the two highest tides per month called?
• How often each day do tides occur?
• What is the the lowest tide called?
• How many really low tides do we have per month?
• What has to be aligned to have a very, very high tide?
By: Mr. D'Angelone 15
Answers
• An spring tide
• Twice
• A neap tide
• two
• the Earth, moon, sun
The End