First try doesn't quite imitate a 13 year old's science experiment

Previous post refers to a kid's video about proving "global warming in a jar".  I'm not sure I'm proving anything given the comments, but I thought I'd try it out anyway.  Today was a dry run, so no video of my misadventures.

I wanted to do it cheaper, first of all, so no heat lamps or seltzer sources.  My thought was carbonated water versus regular water, and my heat source is the sauna at the gym.  I followed the NASA recipe where I hit my first snag, with trouble finding thermometers that I could stick through bottle caps.  No luck at the hardware store, and then thought I had the genius solution of using perfect-sized digital thermometers from the drug store.  Failing to read the fine print, I missed that these medical thermometers only register temps between 90 and 110F.

I thought it might still work though by placing them on the floor of the sauna.  Filled the bottom quarter of two bottles with water in one, cabonated water in the other, both waters starting at the same temp (kept the source bottles together in the backpack before pouring into receiver bottles), stuck them on the sauna floor and sweatily waited five minutes.  First reading was 107 for carbonated, 108 for regular.  Both increased temperature while I watched - within seconds, carbonated was warmer than regular, then within a minute it hit 110 and became useless.  The other took about three minutes to do the same.

I remove the bottles and me from the sauna.  The water at the bottom of both still seemed cool to touch, all the warmth was at the top of the bottles.  I was chagrined to realize I had put just slightly more water in the control than soda water in the experimental bottle, so even my very limited data has a problem.

So obviously the next step is get the right thermometers.  I'd also like to try it outside on dark pavement on a sunny day, but the sunny days lately have been pretty windy.  I think if I could leave the bottles in the sauna long enough, I might also be able to get enough water vapor to have an effect/feedback.  Maybe one bottle with baking soda and vinegar, one with water, one with carbonated water, and a control.