HR: 1340h
AN: ED13C-1160    [Abstracts]
TI: The Ocean`s Thermohaline Circulation in a Fish Tank
AU: * Lavender, K
EM: klavender@sea.edu
AF: Sea Education Association, P.O. Box 6, Woods Hole, MA 02543 United States
AU: Joyce, P
EM: pjoyce@sea.edu
AF: Sea Education Association, P.O. Box 6, Woods Hole, MA 02543 United States
AU: Graziano, L
EM: graziano@sea.edu
AF: Sea Education Association, P.O. Box 6, Woods Hole, MA 02543 United States
AU: Harris, S
EM: sara@eos.ubc.ca
AF: University of British Columbia, Department of Earth and Ocean Sciences, 6339 Stores Road, Vancouver, BC V6T 1Z4 Canada
AU: Jaroslow, G
EM: garyj@sea.edu
AF: Sea Education Association, P.O. Box 6, Woods Hole, MA 02543 United States
AU: Lea, C
EM: clea@sea.edu
AF: Sea Education Association, P.O. Box 6, Woods Hole, MA 02543 United States
AU: Schell, J
EM: jschell@sea.edu
AF: Sea Education Association, P.O. Box 6, Woods Hole, MA 02543 United States
AU: Witting, J
EM: jwitting@sea.edu
AF: Sea Education Association, P.O. Box 6, Woods Hole, MA 02543 United States
AB: This demonstration develops intuition about density stratification, a concept critical to understanding the ocean`s thermohaline circulation. In addition, students learn how temperature and salinity affect density, how these characteristics may be density-compensating, and students gain practice in graphing and interpreting vertical profiles and temperature-salinity (T-S) diagrams. The demonstration requires a rectangular fish tank (5-10 gallons) with a plexiglass partition, preparation of three colored ''water masses'' representing surface water (warm and fresh), ''mystery'' Mediterranean Water (warm and salty), and North Atlantic Deep Water (NADW; cold and salty), a kitchen sponge, and a temperature and salinity probe. Density may be computed using an Equation of State calculator (e.g. online version at http://fermi.jhuapl.edu/denscalc.html). The larger side of the fish tank is filled halfway with NADW, then surface water is layered on top by carefully pouring it on a floating sponge. A student volunteer measures the temperature and salinity of the two water masses, while another computes the densities. Students draw vertical profiles and T-S diagrams representing the temperature, salinity, and density of the water column. The properties of the ''mystery'' water are measured and students predict what will happen when the water is poured on the opposite side of the partition and is allowed to overflow into the layered water. If the density gradients are sufficiently large, a beautiful internal wave develops as the mystery water overflows the sill and becomes intermediate Mediterranean Water. If time permits, having a student blow on the surface illustrates the limited influence of ''wind'' with depth; an internal wave may by forced by depressing the thermocline with a large, flat spoon; and pouring extra NADW on the sponge floating at the surface may illustrate deep convection.
UR: http://www.sea.edu
DE: 0805 Elementary and secondary education
DE: 0810 Post-secondary education
DE: 0820 Curriculum and laboratory design
DE: 0845 Instructional tools
DE: 4283 Water masses
SC: Education and Human Resources [ED]
MN: Fall Meeting 2005