That’s not really showing temperature stratification which is a more extreme separation of temperature from surface
I think the definition you are using is far too restrictive, in many contexts temperature stratification simply refers to a situation where you get temperature gradients across a fluid with the warmer fluid gathered near the top of the body. For example, in a factory you will often have “destratification” fans operating because warm air from equipment rising to the ceiling results in a temperature gradient from floor the ceiling.
It is not a phenomena exclusive to surface heating.
That’s just showing that the hottest atoms gather to the top, which btw, proves Convection currents.
Yes. My point was not to establish that convection is magically absent from fluids in microwaves, but to establish that it differs significantly from stovetop heating. Convection currents in stovetop heating create a strong stirring action that produces a substantially uniform temperature. Microwaves do not create the same stirring action and this produce a significant nonuniform temperature gradient.
The modified glass is just diverting the hotpots to the bottom to make the convection less “unusual”.
Clearly. They make the heating more akin to a stovetop, which is really the point here.
They aren’t claiming that convection doesn’t accrue, only that it’s “unusual convection” resulting in less even heating like that of thermal stratification, not literal thermal stratification where the layers have separate convection currents that prevent mixing all together.
Once again, you are using a definition of thermal stratification that is far too specific. However, arguing over it is really just being pedantic because the core point at issue here is whether or not heating a cup in a microwave or a stovetop produce the same final product. They do not unless you apply some mechanical agitation to mix it up.
using a definition of thermal stratification that is far too specific
I’m using the textbook definition of which there are at-least three distinct layers that prevent mixing due to distinctly separate convection currents separated by the thermocline layer.
While the top has a considerable difference of ~18F at 95-113F, the rest is pretty evenly 77-86F.
By you’re less strict definition, after applying conventional bottom-up heating, Thermal stratification would also occur in this 2 layer form just by letting it sit and settle for a bit as the hotter atoms rise to the top due to their lower density creating a distinct hotter top with the rest holding a pretty even temp.
Matter of fact, the steam is just moister in the air combining with the hottest water atoms that are yeeting themselves out from the surface as vapor.
Search the literature for thermal stratification. There are many contexts where it is used outside of lakes and other large bodies of water, many of which do not consist of three distinct layers. Hell, the paper I cited SPECIFICALLY refers to the temperature gradient in the microwaved glass as “stratification”.
If you can’t understand the use of a term outside your specific area of expertise then thats honestly a you problem and that’s all I can say on that.
If the heating methods were as similar as you say, there wouldn’t be hundreds of publications accepted to various journals across the past two decades investigating the problem where microwaves produce a strong temperature gradient between the top and bottom of a body of liquid. It’s a well known process control problem.
I guess this does count as a more gradual example of thermal stratification where 35C is the thermocline layer.
However, by this definition, thermal stratification would still occur after applying conventional bottom-up heating by letting it sit and settle for some time allowing gravity to sort by density resulting in a very similar stable thermal stratification pattern.
You’d have to be constantly mixing or never take of the heat source to prevent this stable thermal stratification pattern from occurring.
