Tell me why

Okay, first a disclaimer: this blog has little to do with the farm or the animals. Those of you who read this blog regularly know that I like to understand how and why things work. I spend much of my time with the flock looking at details and thinking about what I see. Right now a mystery is bugging me — so much that it’s distracting me from all I need to do. As a result, I’m posting it here in hope that someone will have a good explanation. The puzzle is starting to make me a bit crazy. Please help!

On the day before my birthday in early June, I poured my morning iced coffee (my typical summer routine) and then noticed that after I filled my glass, there was just enough left in the jug for one more morning. I poured it into a glass, topped it with a screw lid, and put it into the refrigerator to be enjoyed the next day.

This beautiful sight greeted me in early June as I removed the lid from my coffee: beautiful concentric circles created in the foam of the cream!

This unusual sight greeted me in early June as I removed the lid from my coffee: beautiful concentric circles created in the foam!

When I pulled the glass out of the fridge the next morning and took off the lid, I was surprised to see a lovely pattern in the creamy foam on the top of the coffee (left). The cream had been added when I originally made the jug of coffee, but I had never seen this type of pattern in the jug or glass. It was beautiful! Like most such surprises in my life, I photographed it for future study. I told myself that life had given me this lovely creation because it was my birthday, and with Rick out of town on business, it made the day special. I sent the photo to several people, asking how on earth this had come to be, and I eagerly awaited the replies as I continued to puzzle it out myself.

The consensus of my email friends was that the rings were caused by vibrations that created standing waves in the coffee. Overnight, the refrigerator had run, causing small vibrations that had set up the rings in the foam. It made sense to me, and I was happy to have an explanation. My curious mind was calmed and settled, and I moved on to other activities and thoughts — until today!

Yesterday, I once again poured out my morning iced coffee and noticed that there was enough remaining in the jug for the next morning. I again filled the same glass with the remaining coffee to the same level and slipped the same lid over the top, putting the lidded glass into the refrigerator. Overnight, I eagerly awaited the concentric rings of cream in my coffee. This morning, I carefully took the glass from the shelf of the fridge and placed it on the counter. I slipped the lid from the glass, trying not to cause any movement that might disturb the pattern I expected to see. Yet, when I removed the lid, all I found was the coffee you can see in the photo on the right below. No rings!

This morning's coffee - without the beautiful concentric rings!

This morning’s coffee, without the beautiful concentric rings!

So now my mind is once again abuzz: why were there no rings in my coffee this morning? The obvious answer is that it wasn’t my birthday! But seriously, now I really want to know. If it was originally a case of standing waves from the vibrations of the fridge, then I should have seen those same circles from the same vibrations of the same refrigerator. It was the same glass, the same lid, and the same shelf. The fridge is loaded with about the same amount of stuff, so what happened? Where, oh where, are my rings?

My mind is churning through possibilities, but I’m not coming up with anything that really makes sense — nothing that leaves my mind satisfied enough to move on. I need to figure this out! I have a lot to do, including figuring out this fall’s breeding groups, and here I am puzzling over a glass of iced coffee and absent concentric foam rings!

So I ask: do you have any idea why my coffee had no rings this morning? I would love to know, and I look forward to reading your thoughts. Thanks in advance!


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  • Jane says:

    Okay I do not know but here is my guess. I think your friends saw the original pattern as being like a Chladni plate. Google Chladni patterns and check the images as well as the article on Chladni himself. There is a youtube video that shows patterns being created, and the google images show sequences that include your coffee cup pattern. However the patterns are very dependent on frequency and change quickly. In a round coffee cup not many of them would stay I’m guessing. So bottom line (maybe) It Was your birthday and you happened to hit the exact amount of coffee, foam,and refrigerator vibration for a lovely surprise. Maybe.

    • Dee says:

      Oh, Jane, your comment made me smile! I will certainly read more about Chladni and the plates, and hopefully my brain will be satisfied enough with the explanation that it will once again shift back to focus on more practical matters! Thanks!

  • Elisabeth says:

    My first thought was.. was the cup in the same place in the fridge? Was there more or less traffic to the refrigerator that day as the previous day? I wonder if maybe you were in the fridge less so the fridge ran less and it was able to maintain temperature without running as often as it had when it occurred the first day!

    • Dee says:

      The glass was in the same place in the fridge and had about the same amount of traffic since I was the only one home – and my routine when I am home alone is pretty much identical from day to day. Besides that, the last hours are in the overnight, so no one is in the fridge at all between about 9 p.m. until I open it in the morning – when one day I saw the lovely circular designs in my coffee and the next time, I saw just plain old foam!

  • Emily Sappenfield says:

    Was the cream the same? I’m wondering if the amount of time elapsed since the carton was opened could affect the texture. An alternate explanation, of course, is gnomes.

  • Alexis says:

    I just had the same experience with a cup of coffee left in the fridge overnight. I came across your account when I ran a Google search attempting to shed some light on the mystery rings I uncovered the next morning. Did you figure anything out? The concentric patterns in my coffee cup were actually quite beautiful. Wish I could post a picture here!

    • Dee says:

      If you send me the photo by private email, I will post it to this blog with an update about your experience! Wasn’t it beautiful, though? It seemed magical when it happened here, but no matter how hard I try to recreate it, I’ve had no luck. Thanks for sharing your experience!

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