This image shows the SBE 19plus CTD instrument made by Sea-Bird Electronics in Washington State. The HIGH TIDE project uses this model of CTD to measure the water in lower Chesapeake Bay in order to note how salinity, temperature and density change with different wind conditions and various freshwater discharges into the Chesapeake Bay area. Clicking on this image will show you a collage of pictures showing the SBE 19 CTD instrument in use by the HIGH TIDE project.
Click on image for full size
Sea-Bird Electronics, Inc.
Scientists have been interested in the characteristics of water for a long time. Benjamin Franklin
even measured the temperature and salinity of the Atlantic Ocean in the 18th century. Nowadays, scientists use CTD instruments to measure water
characteristics like salinity
, pressure, depth and density
. CTD stands for Conductivity-Temperature-Depth. You can see a picture of a CTD instrument to the left.
A CTD instrument is placed in the water it is measuring. It can store the measurements it takes or it can send the measurements through a cord to a personal computer on ship or on dock. CTD profilers are pretty fancy equipment, but they can be used in all sorts of situations. The HIGH TIDE project has high school students using a CTD to measure water characteristics in Chesapeake Bay. And they lower their CTD from a bridge into the water below!
Shop Windows to the Universe Science Store!
The Summer 2010 issue of The Earth Scientist
, available in our online store
, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.
You might also be interested in:
Almost 3/4 of the Earth is covered with water. Almost all of that water is in the oceans. Have you ever been swimming in the ocean? If you have and you accidentally got water in your mouth, you know the...more
An aquifer is the name for a layer of rock which is capable of holding a large amount of water. Some layers are better at holding water than others, for example a layer of sandstone can hold a good deal...more
Limestone is an example of a carbonate. Other examples of carbonates include calcite, dolomite, and marble. Limestone dissolves easily in rainwater, especially rainwater which is loaded with carbonic acid....more
The deep ocean waters are under pressure and are much colder than layers of the ocean which are closer to the surface. Dissolved carbon dioxide seems to be absent from the deep ocean water and as a result...more
Have you ever left a glass of water out for a long time? Did you notice that the water disappears after a few days? That's because it evaporated! Evaporation is when water passes from a liquid to a gas....more
The water at the ocean surface is moved by powerful wind. The wind is able to move the top 400 meters of the ocean. This moving water is called surface ocean currents. Surface ocean currents form large...more
Rivers are very important to Earth because they are major forces that shape the landscape. Also, they provide transportation and water for drinking, washing and farming. Rivers can flow on land or underground...more