WAVES, CURRENTS,

TIDES

Q: TIDES…What are they?A: periodic rise and fall of large

bodies of water

Tides are daily changes in the level of ocean water.

Over 2000 years ago, a Greek explorer named Pytheas discovered that there was a relationship between the moon’s phases and the tides, but he could not tell us how the moon caused the tides.

Year 1687- Sir Isaac Newton

When Isaac Newton’s theories of gravity were first published, an explanation of how the moon’s gravity can cause tides could be explained scientifically.

Q: What is the dominant force on Earth’s tides?

A: The moon’s gravitational pull

How often tides occur and the difference in tidal levels depend on the position of the moon as it revolves around the Earth. The moon’s pull is strongest on the part of the

Earth directly facing the moon.

http://astro.unl.edu/classaction/animations/lunarcycles/tidesim.html

Tides occur at different areas on Earth because the Earth rotates more quickly than the moon revolves around the Earth.

TIDAL RANGE- the difference between levels of ocean water at high tide and

low tide.

Q: Does the sun affect the tides?

A: It does but it is so far away so the sun’s influence is less powerful than the moon’s

influence.

High Tide vs. Low Tide

SPRING AND NEAP TIDESCan you guess which moon phase is happening at each of the tides?

SPRING AND NEAP TIDESCan you guess which moon phase is happening at each of the tides?

SPRING TIDES occur when the sun, moon, and earth are aligned. Spring tides have the largest tidal ranges and occur during

the new and full moon phases.

NEAP TIDES occur when the sun, moon, and earth are at right angles to each

other. Neap tides have the smallest tidal ranges and occur during the 1st and 3rd

quarter moon phases.

Let’s REVIEW!!!• Tides are caused by the gravitational forces of the moon and sun on the Earth. But…• The moon’s gravity is the main force behind the tides.• The positions of the sun and moon relative to the position of the Earth cause tidal ranges.• The four different types of tides are: high tides, low tides, spring tides, and neap tides

Study Jams Video- Tideshttp://studyjams.scholastic.com/studyjams/jams/science/weather-and-climate/tides.htm

Q: What are currents?A: continuous, directed movement of water generated by different forces.Currents move water and objects across the ocean.

Q: What causes currents?A: currents are caused by wind, the Earth's rotation, and differences in water density within oceans

Q: What are deep ocean currents?

A: They are currents deep within the ocean that are the result of changing water density. The more salty and cold ocean water is the denser is it. More dense water drops to the bottom of the ocean and separates from less dense water, and that movement creates a current

Q: What are surface ocean

currents?

A: Surface currents carry warm and cold water around the globe. The Gulf Stream carries warm water from the Gulf of Mexico (warm water) up the East coast, to North-western Europe. These countries should be cold because they are so far north, but the warm current makes the air above warmer, thus making the climate warmer.

Q: What are waves? Draw and Label this pictureA: Waves are energy passing through water that make it rise and fall.

Q: What causes waves? Draw and Label this pictureA: MAINLY wind, & underwater earthquakes and landslides.