Hello, I'm Korey Champe.
Today I will be highlighting the Density Circulation Apparatus used with PASPORT probeware and
SPARKvue software.
The Density Circulation Apparatus is new to PASCO, and today I will highlight its use
in an Earth Science application, modeling a thermocline.
The apparatus is two one-liter plexiglass containers connected by two flow valves, which
allow water to flow between the chambers.
Today's activity comes from the user's manual, which is supplied with the apparatus.
The manual offers this and other experiments to accompany the apparatus.
To perform this activity, we start with two water bodies of different densities.
In this case, the density difference is driven by temperature.
We could also use salinity, or both temperature and salinity.
I've added food coloring to help differentiate the waters and to help see what happens when they mix.
And now, the second water.
OK. Now, I've preconfigured the software to save some time and I will be taking manual
samples at 1 centimeter intervals along the markings on the side of the tank.
First, I plug in my Temperature Sensor and push Start to begin sampling.
Initially, I'm just going to show you the difference in temperature between the two chambers.
And it's just about stabilized.
And now let's check the other chamber.
So there's clearly a difference in temperature between these two water bodies.
OK. Now I'm going to open the valves and let the water interact. I'll start with the upper chamber.
And now, the lower chamber.
Make sure to focus in on looking at the bottom chamber as the water interacts.
You can see that there's a smooth continuous flow as the water bodies interact, and this
is true for even very small density differences.
OK, looks like they have finished mixing and now we want to model our thermocline.
As I mentioned before, the software was preconfigured to save time.
And as you can see, I have a table set up with depth in one column and temperature in
the second column.
So I'm going to start collecting data.
First data point.
And then, second data point.
OK. And we've collected all 20 data points, so I'm going to stop the data collection.
And now to look at the data I'm going to build a page.
We're going to plot depth on the y-axis and temperature on the x-axis.
And you can see that we have our idealized thermocline.
I'm going to scale-to-fit to make sure that the data is fitting the screen completely.
And a thermocline is defined as a rapid temperature change over a very small depth, and you can
see that our thermocline does show that.
We had a very, very rapid temperature change -- on the order of 15 degrees -- in this very,
very small space.
This is exactly what we'd expect to see in an idealized thermocline.
As I mentioned before, this experiment could be performed with salt and temperature using
PASCO Salinity Sensor, so you could use salinity to define the density differences.
There are many other experiments students can perform with the Density Circulation Apparatus,
including convection and temperature inversions.
This completes the experiment. We hope you've enjoyed the demonstration.