Sławatycze · ice from an oxbow lake of the Bug
July on one side, January on the other, and a layer of sawdust between them. This cross-section separates three things that are easy to confuse in the story of an icehouse: heat from outside, insulation, and water that drains away or stays put.
July · air
Outside
Heat presses on the surface of the stack. In the model it is a single number Q, not a temperature in degrees.
Q is the heat input in conventional units from 0 to 100. It is not the weather in Sławatycze or a measurement; it serves only to compare two covers.
Insulation
Sawdust
They reduce how much heat reaches the ice. In the model: parameter S.
The description of the tradition says that the stack was covered with sawdust. Why sawdust insulates: it is porous, and still air in the voids conducts heat poorly. This is a general explanation, not a measurement from Sławatycze.
The thickness of the layer and the kind of sawdust are not given in the material supplied: no data, not zero.
January sealed in the stack
Inside
A compact stack of ice slabs. In the model it starts with 100 units of ice.
According to the description, slabs were harvested in winter from an oxbow lake of the Bug and laid in a large stack called a pyramid. The drawing is general: the number and size of the slabs and the local construction are not established.
Meltwater drainage · this is not insulation
Drainage does not change how much ice melts. It only decides whether the water lies in the store or outside it.
The description of the tradition supplied says nothing about water draining from the stack in Sławatycze: it is an element of the diagram, not a fact about that place.
In the model, water does not speed up melting. In a real store, standing water could change the heat exchange; we do not calculate that here.
Take off a layer · teaching model
Every bar below is the same 100 conventional units. The two rows have different covers, the two columns different drainage, and the heat Q is shared. Take the cover off variant B and compare the rows, then glance at the columns: the ice changes only between rows.
Rules of the model (always the same):
Ice difference A − B
Without JavaScript you see example values: Q = 60, cover A = 70%, cover B = 20%. The sliders require JavaScript.
Drainage: yes
Drainage: no
Drainage: yes
Drainage: no
Variant A (cover 70%) keeps 30 units more ice than variant B (cover 20%): 82 versus 52 at Q = 60. Changing the drainage in the same row does not change the ice; it moves water between ‘lies in the store’ and ‘outside the store’.
Assumptions: initial mass 100 units, S in the range 0–90% (a cover does not insulate one hundred per cent), Q in the range 0–100. Drainage does not affect the rate of melting. The result illustrates a relationship; it is not a forecast of the fate of any real stack.
The evidence and its limits
According to the description of Lody sławatyckie [Sławatycze ice cream] on the List of Traditional Products, ice was harvested in winter from an oxbow lake of the Bug, carried on carts, laid in a large stack described as a pyramid and covered with sawdust with summer in mind, when it was needed to make traditional ice cream.
This description was carried over from the previous version of the page; the source was not reopened at this stage, so it needs to be checked again. It describes a custom, not the design of an icehouse or the fate of a single block. It contains no loss curve, so a rate of melting cannot be calculated from it.
Melting changes the state of matter; it does not destroy mass: ice becomes water. That is why the total in the model is always 100.
| From the evidence | In the model |
|---|---|
| Slabs in winter from an oxbow lake of the Bug | 100 conventional units of ice at the start |
| Stack described as a pyramid | General cross-section through the stack |
| Covering with sawdust | Parameter S: 0–90% reduction of heat input |
| Water drainage: no data | The drainage switch decides only where the water is |
| Thickness of sawdust, dimensions of the stack, rate of melting: no data | Q is a conventional number; the model does not give a date of melting |
Sources and caveats
