Waves TidesCurrents What’s the difference?
WaveS • Definition: • Movement of energy through water • Created by energy being transferred from the wind through the water
Factors that affect the height & size of a wave • Strength of the wind • Length of time the wind blows • Distance over which the wind blows
Main parts of a wave: Trough = lowest part of the wave (bottom) Crest= highest part of the wave (top) Wavelength = horizontal distance between crests & troughs Wave Height= vertical distance between crest & trough http://soschem.blogspot.com/2009/11/parts-of-wave-diagram.html
Tsunami waves result from earthquakes releasing energy underwater *The most damaging part of a tsunami wave is the wave height.
Waves are a form of energy that travels through water. The water does not actually move, but instead the energy is moving. The particles move in a circular path.
A breakerwave at the beach crashes into the shore because the shore slows the bottom of the wave, but the top continues to move forward. Surfers ride breaker waves to the beach. (Microsoft Clip Art)
Waves during a stormDuring a Storm, waves can get very large and strong (Microsoft Clip Art
TIDes • Definition: • The daily rise and fall of Earth’s water on its coastlines (Microsoft Clip Art)
Causes of tides: • Gravitational pull of the SUN & MOON http://ircamera.as.arizona.edu/NatSci102/NatSci102/movies/tides2.gif
Examples of Tide cycles: • Daily Tide Cycle: • HIGH & LOW – • 2 times each day • 12 hours apart
Monthly Tide Cycles: • SPRING tides occur when the Sun, Moon, & Earth line up straight. • (form a straight line or straight angle, 180 degrees) • These occur during Full & New Moons.
Monthly Tide Cycles: • NEAP tides occur when the Sun, Earth, & Moon form a right angle. • (Makes a 90° angle, “like a bent knee”) • These occur at (1st ) & (3rd ) Quarter Moons
Misc. info about tides: • If it’s low tide at 4 am, when will the next low tide occur? 4 pm (they happen 12 hours apart!) • Draw a picture of the Moon, Earth & Sun aligned during a SPRING TIDE: • Draw a picture of the Moon, Earth & Sun aligned during a NEAP TIDE:
Currents • Definition: • Large streams of moving water that flows through the oceans. Surface currents are driven by the wind.
Factors that affect CURRENTS: • Coriolis Effect • & • Temperature
Factors that affect CURRENTS: • a. Coriolis Effect– the shifting of winds and currents caused by Earth’s rotation. As Earth spins it causes the winds & currents to follow a certain path. • Currents and Winds in the Northern Hemisphere move clockwise • Currents and Winds in the Southern Hemisphere move counter clockwise
Coriolis effect causes currents to move in specific directions http://www.pinellascounty.org/newsletters/e-lert/images/feb_2010/coriolis-effect.jpg
Temperature • Warm currents flow from the equator toward the poles. • The water becomes dense as it cools. The cold water flows back towards the equator. This cycle is similar to convection currents
Convection currents in the oceans http://www.nature-education.org/currents.gif
The GulfStream is one of the most famous surface currents. This current has been used by sailors to speed up their travel times. It exists because of the winds that blow in regular directions.
UPWELLING: • is the circulation in the ocean that brings cold water to the surface. This is caused by winds pushing the top levels of warmer water away, which allows the colder water to rise and fill the area. Schools of fish live in this area because of the nutrients. http://www.pnas.org/content/105/6/1965/F1.large.jpg
Misc. info. About currents: • RIP CURRENT – rush of water that flows rapidly back to sea through a narrow opening in a sandbar http://www.buoybuddy.net/Rip_Current_Diagram.html
What causes cold deep currents to begin moving in the oceans near the poles? The sinking of cold dense water from the poles causes deep cold currents to begin moving in the oceans near the poles.
How are waves, tides & currents different? • Which is caused by gravitational pull between the Earth, Sun & Moon? • Which is a large stream of water flowing through the oceans? • Which is formed as energy is transferred from the wind through the water? • What do we call the monthly tide cycles? • Currents and winds curve and move due to the spin of Earth on its axis. This is called the _______ effect. • What are the 3 factors that affect the size of ocean waves? • Warm currents near the equator flow towards the poles & cold, dense water near the poles flows back towards the equator. This causes ________ currents in the ocean. • Daily tide cycles that happen 2 times everyday & 12 hours apart are called _____ & _____ tides.