Enter the  Main Exhibit Here Lessons Index: 1. MAP AND CHART 2. CHARTING THE GREAT WINDS 3. RIDING THE WIND 4. THE MAP CARTOUCHE 5. THE GULF STREAM 6. CHART MAKING FOR NAVIGATORS 7. HURRICANES 8. PROFILES 9. CHARTING NEPTUNE’S REALM 10. SURFACE CURRENTS 11. DENSITY CURRENTS 12. CURRENT AND CLIMATE 13. HUMAN INTERACTION 14. DEFINING THE EARTH 15. LATITUDE 16. LONGITUDE 17. COMPASS DEVIATION Osher Map Library University of Southern Maine

Charting Neptune's Realm: From Classical Mythology to Satellite Imagery An exhibition at the Osher Map Library and Smith Center for Cartographic Education, University of Southern Maine, Portland, 4 April 2000 to 11 January 2001 Donald S. Johnson, guest curator Lesson 11g - Glossary DENSITY CURRENTS Osher Map Library Lesson Charting Neptune's Realm Hope McVane A. Learning Objectives B. Background Information C. Teacher Activities D. Materials Required E. Presentation of Lesson F. Extensions G. Glossary Density: mass divided by volume, mass per unit volume Density current: circulation of water due to differences in density Gulf Stream: Northern flowing warm water current Salinity: measure of the quantity of dissolved salts in seawater; usually expressed as parts per thousand Salinometer: instrument used for determining the salinity of ocean water by measuring the electrical conductivity of water at a certain temperature Thermohaline circulation: vertical circulation caused by changes in density, driven by changes in temperature and salinity I. Further Reference Ocean Circulation Introduction http://www.geosun1.sjsu.edu/~dreed/onset/exer11/1.html An Introduction to the Worlds Oceans, 4th edition Allyn & Alison Duxbury Wm. C. Brown Communications, INC IA 1984 Return to Lesson 11 Index Return to Charting Neptune's Realm index of lessons Return to Osher Map Library's complete list of lessons on the web