The Waters of the Ocean

The Unique Nature of Pure Water

The Three States of Water

Heat and Water

Water as a Solvent

Seawater

Salt Composition

Salinity, Temperature, and Density

Dissolved Gases

Transparency

Pressure

Motion in the Ocean

Surface Circulation

The Coreolis Effect

Wind Patterns

Surface Currents

Waves

Tides

Why Are There Tides?

Tides in the Real World

Vertical Motion and the Three-Layered Ocean

Stability and Overturn

The Three-layered Ocean

 

Boxed Readings:

• Tall Ships and Surface Currents
• Waves That Kill

Chapter Summary

Chapter 3 outlines the basic chemical and physical characteristics of the ocean, stressing their relevance to the distribution of life in the marine environment.

• The basic chemical and physical characteristics of water and of seawater.
• How marine scientists measure various chemical and physical parameters
• Motion in the ocean: surface circulation, waves, tides, and vertical motion.
• Two box readings demonstrate the practical relevance of understanding ocean currents and waves.

Answers to Critical Thinking Questions

1. The winter of 1984-85 was particularly cold in Europe. The northern part of the Black Sea, which lies between the Ukraine, Russia, and Turkey, froze, which is rare in the normally mild climate. The Adriatic Sea, located to the east, had just as cold a winter but never froze. The Black Sea has an unusually low salinity of about 18^o/_oo. What would you guess about the salinity of the Adriatic?

The salinity of the Adriatic Sea has to be higher. It actually varies between 38-39^o/_oo in the south, to 33-25^o/_oo in the north.

2. Just for the fun of it, someone walking along the shore in Beaufort, South Carolina, throws a bottle with a message in it into the sea. Some time later, someone in Perth, on the west coast of Australia, finds the bottle. Referring to Appendix B of this book or Figure 3.19, can you trace the path the bottle probably took?

The most probably route is: Gulf Stream, Canary Current to the Equator, South Equatorial Current, Brazil Current along the east coast of South America, Antarctic Circumpolar Current, and finally north along the west coast of Australia.

3. If you owned a seaside home and a bad storm brought heavy winds and high surf to your coastline, would you prefer it to be during new moon or a quarter moon? Why?

A storm during a quarter moon would be less destructive because tidal range is at its lowest. The highest tides are observed during new and full moons. A storm during these periods would be more destructive since storms cause tides that are higher than predicted tides.

4. Most tsunamis occur in the Pacific Ocean, as indicated by the map in the Waves that Kill box reading. How would you explain this?

The Pacific basin is almost entirely circled by boundaries of plates and hence areas of frequent earthquakes (see Figs. 2.7 and 2.10).