Our Oceans

  1. Label the world’s 5 main oceans on the map.
  1. Salinity is the measure of the amount of salts dissolved in a liquid. On average how much salt does ocean water contain?
will accept3% – 3.5%
  1. What is the most common salt present in ocean water?
sodium chloride (NaCl) /
  1. What is the average depth of the oceans? 4000 m will accept 3790 – 4000 m
  1. What is the deepest place in the ocean? How deep is it?

Marianas Trench, 10916 m (35814 ft)

will also accept Challenger Deep which is the deepest part of the Marianas Trench

WavesGO TO

  1. Describe the most common way that waves are produced in the ocean.

Wind is the most common way waves are produced.
Wind blowing on the surface of the water creates friction between the air and water… and causes the water to ripple or form waves.
  1. What determines how big the waves will become?

The strength of the wind, how far it blows (fetch) and how long it blows (duration)
determine how big the waves will become.
  1. Ocean waves are divided into several parts. Draw a diagram of a wave, label its parts, and give a description of each. (crest, trough, wave height, wave length)

/ Crest is the highest point on a wave.
Trough is the lowest point between two waves.
Wavelength is the horizontal distance between 2 wave crests, or between 2 wave troughs.
Wave height is the vertical distance between a wave’s crest and trough.
  1. What is a wave period and how could you measure it?

The time it takes for 2 consecutive wave crests (or troughs) to pass a single
stationary point. Essentially how fast the wave is moving.
  1. When we watch waves it seems as if the water is moving forward, but its not! Describe what is really happening.

Water particles actually move in a circle and therefore stay in one place.
Energy is moving forward through the water in the form of a wave.
Energy is transmitted from one water particle to the next when they collide.
It’s like a chain of dominos falling… the energy moves forward to tip over each consecutive domino… but the domino itself falls in place.

Currents

  1. Currents keep our oceans in constant motion. What 3 things help to produce them?

wind, tides and gravity
  1. Currents travel north and south in the ocean, usually circling away from the equator. They move in big loops called gyres. Describe how and whythese gyres are different in the Northern and Southern Hemispheres.

Currents move in loops because of the Coriollis Effect – the Earth is spinning and currents are deflected from a straight path to a curved motion.
In the northern hemisphere currents are deflected in a clockwise direction.
In the southern hemisphere currents are deflected in a counterclockwise (opposite) direction.
  1. What do you think will happen to the temperature of the water as it moves away from the equator?

It starts out warm at the equator and gets cooler as it goes north/south toward the poles.

Tides

  1. What are tides and what causes them?

Tides are the periodic rise and fall of the ocean waters.
They are caused by the gravitational pull of the moon (& sun) and the rotation of the Earth.
  1. Why do tide levels change in a 24-hour period (i.e. high tide and low tide)?

The moon travels around the earth and so its position compared to an ocean changes in a 24 hour period.
The gravitational pull of the moon on the ocean changes with its position – oceans closest to the moon have the greatest pull and this creates high tide. Oceans farthest from the moon have less pull and this creates low tide.