[Geysers] Re: geysers

[Alan Glennon]

--- original message  --- 
  From: AMYKARMAK at aol.com 


  Alan-  We came across your web site when we were searching for additional info. on geysers for my sons' (3rd grade)  science fair project.  I thought that maybe you could offer some suggestions to help us out. . . My son found an experiment on www.exploratorium.edu that sparked his interest in geysers and, therefore, has lead him to want to do his science fair project on geysers. We can't, however, fiqure out a question and hypothesis (prediction) to base the project on-  Do you have any opinions or suggestion for us?  Any advise or referrals to other web sites would be so helpful~ Thank you.
-------------------
Amy,

I forwarded your email to the other geyser observers; perhaps they have comments or could correct any conceptual or logic problems in my suggestions... hopefully, my rambling, off-the-cuff answer, will provide you some ideas...

Coming up with testable geyser hypotheses for science fair projects can be a tricky -- particularly, since it tends to be hard to build a realistic geyser model on which to conduct tests; it's quite dangerous too. However, assuming you're thoughtful and careful, once the geyser model is built, it's lots of fun.

When I make a model geyser, I tend to make variations of the following:
http://www.wyojones.com/science_fair_projects_and_geyser.htm

Again, if you build one of these things--> be very, very careful!

Once built, the model will lead to questions like:
Is there a relationship between the length (depth) of the geyser's tube and the eruption height?
How does the outlet location of the geyser's reservoir affect the eruption height or duration (where the bottom of the tube is located in the beaker)?
What happens when I use two vents instead of one, what if they're at different levels on the top or bottom? Note to geyser people: I made wonderful model of Whirligig experimenting with this question.

In my university lab, I was able to make minor, intermediate, and major eruptions by connecting two models; of course, that takes more and more glassware.

It may be possible to do something similar with carbonated water, but I've never tried. That'd be a lot safer, and then you could use plastics and standard-type tubing. It would be a delicate balance between overlying water pressure and CO2 wanting to escape. If nothing else, when building a model, it's easy to see why geysers are so rare. Minor changes in the model (particularly vent diameter) make the difference between violent eruption and gentle overflow. 

In fact, if you have a way to measure the pressure coming out from a waterhose, you could look at pressure versus orifice size and the resulting "eruption" height. Without measuring pressure, you could hold pressure constant and if you could somehow measure the size of the waterhose outlet (and change it using various spigot sizes), you could track how orifice size changes the height water is expelled. Since we can estimate Old Faithful's orifice size and height, we could backtrack and get an estimate of its pressure. Of course, if you don't have a way to measure the pressure, you could keep it constant and obtain an answer like: Old Faithful has 10000 times more pressure than my waterhose. A statistician would be unhappy with such a large extrapolation -- but of course, there are small geysers too. See my article on El Tatio geysers -- I'll make the full text available in pdf for the next day or two at http://www.uweb.ucsb.edu/~glennon/travel/tatio.htm  I describe quite a few geysers; look for descriptions of the vents and their heights. You'll probably be able to find a geyser that has a fraction of a typical waterhose's pressure.

A constriction often is present within the geyser's plumbing geometry. In the glassware model, the tube itself accounts for the constriction out of the reservoir. Thus, the constriction is also the vent of the geyser. If you use a rubber tube or waterhose (and a clamp of some sort), how does the constriction's distance from geyser vent change the eruption?

Anyway, those are a couple of random ideas...

Good luck -- be careful -- and if you discover something neat, let me know.
~Alan


J. Alan Glennon, Ph.D. Student
NCGIA/Department of Geography
University of California, Santa Barbara
Santa Barbara, CA 93106
glennon at umail.ucsb.edu
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