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  1. I don’t understand what’s going on, but if I had to guess…
    The particles are bubbles. As the gas cools, the bubbles shrink and cause the fractures seen here.

  2. Hot water at just below 100C deg always has those patterns. They’re tiny droplets of condensed water hovering just above the liquid surface. But usually the droplets are microscopic. Rarely noticed, little discussed.

    The tiny droplets do reflect light strongly, bouncing it back towards the source. So, if you hold a flashlight very near a camera lens, the droplets light up brightly, and the camera picks it up.


    Phone-cams have a bright LED source right next to their lens. That’s the perfect setup for filming the glowing, hovering crowd of water-droplets. The recent spread of phonecam lights now lets everyone notice the weird boundary-layer fluid mechanics! It was always there. But in the past, the secret was only known to we who hold flashlights against the side of our heads while looking for retroreflectors in the vicinity. (Also constantly listen to pickup coils with amplifiers, to find all the weird magnetic signals around us. City-bus overhead cables ftw.)

    The droplets are trapped in the “boundary layer” of air in contact with the liquid. When the liquid moves, it drags the air along. So, patterns of convection in the hot tea will drag the glowing droplets along, forming underwater convection patterns in the air above. Weird.

    What are the little dark lines? Dunno. Probably they’re the moving mouths of micro-tornadoes; little vortex-cores from rising convection plumes which zip along sideways, sucking the hovering water particles upwards. You’ll see the same on outdoor hot tubs in very still conditions (no wind.)

    Blow on the droplets and they’re stripped away (that’s also how wind-chill works.) But then more will appear. Now charge a balloon or plastic bag on your head and wave it over your hot tea. All the hovering droplets will disappear (they’re attracted to merge with the liquid surface. Electrostatic inductive charging, produces image-charge in the conductive liquid.)

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