Weather has storeys
Above the sea of clouds
The height at which you stand and the height of the clouds are two different numbers. Move one, and the other stays where it was.
Without JavaScript you see a single state of the model: situation A (a sea of clouds in the basin), the observer at 1440 m and all three layers at once. The explanation and sources are below.
Where you stand
Five stops instead of a slider for every metre. The position moves only you, not the cloud.
- cloud (model)
- temperature T, solid line
- dew point Td, dashed line
- observer's level
- A, B: points with elevations from the V2 material
Our own diagram, not a map and not a measurement. The outline of the mountains is conventional (the horizontal spacing is not to scale; the elevations of points A and B come from the V2 material and need checking). The cloud, temperature and dew point are a simple one-dimensional teaching model, not a sounding from any particular day. There are no photographs here: nothing in this cross-section is a photograph from the same moment or a record of the time.
Readout (model)
1440 mRównia pod Śnieżką
You are above the clouds
At 1440 m you are 340 m above the top edge of the cloud (1100 m).
Temperature: +1.8 °C, which is 3.8 °C warmer than at the bottom of the basin (400 m: −2.0 °C).
Dew point: −8.5 °C. T − Td = 10.3 °C: unsaturated air (in the model, cloud forms at ≤ 0.5 °C).
Cloud in the model: 400–1100 m
Two points at once
- Szrenica, 1362 m: above the cloud
- Śnieżka, 1603 m: above the cloud
Choose a position or change the air. These are two independent actions.
What kind of air (model)
Choosing a situation does not move the observer's position.
Inversion in the model: from 400 to 1100 m the temperature rises by 6.0 °C, and above that it falls by 0.65 °C per 100 m.
Air saturated from the basin floor to the upper limit of the cap, drier above.
Three things that look like one
1 · The observer's elevation
This is simply your place in the column of air. In the cross-section the position moves independently of the cloud: going higher creates neither a cloud nor an inversion.
2 · Temperature and inversion
In a typical atmosphere the temperature falls with elevation (in the model, by 0.65 °C per 100 m). An inversion is a layer in which it rises. On its own it does not make a cloud: in situation C there is an inversion, but no cloud.
3 · Dew point
A cloud or fog needs saturation. In the model we count the air as saturated when T − Td ≤ 0.5 °C. The same temperature profile with a different dew point gives a different cloud, or none.
21 September 1988: a record from two stations, not a sounding
According to a summary in the V2 material, based on the work of Urban, Migała and Pawliczek (link in the sources; the reading is to be checked against the original), two different states were recorded in parallel on that day.
| Point | Elevation | Record | Vertical profile of T and Td |
|---|---|---|---|
| A · Szrenica | 1362 m | dense fog | no data in the material |
| B · Śnieżka | 1603 m | little or moderate cloud cover | no data in the material |
The time of observation and the vertical profile are not given in the material, so they are not in the cross-section: missing data is not zero or an intermediate value. A sounding cannot be reconstructed from two stations. Situation B in the model gives a similar contrast (A in the cloud, B above it), but this shows a possibility, not a reconstruction of that day.
V2 described the opposite arrangement (cloud only on the highest summit) as possible when air is lifted up a slope; this claim is awaiting verification, and this version does not model it.
Limits of the model, changes since V2, sources
What this model does and does not do
- This is a one-dimensional exercise: a single column of air, elevations of 400–1800 m a.s.l., temperature in °C. It is not a forecast, a sounding or a go-ahead for heading into the mountains.
- A cloud in the model exists where T − Td ≤ 0.5 °C. This is a simplification of saturation.
- In situations with a cap, the cloud reaches the upper limit of the layer that warms with elevation. This assumption is carried over from V2; the position of the cloud top relative to the inversion needs verification by a meteorologist.
- The model does not take into account higher clouds, wind, insolation or orographic clouds. The view from the trail may be different.
Model parameters (to be checked)
- Inversion: from 400 m up to the cap, T rises linearly by ΔT; above that, T falls by 0.65 °C per 100 m. Without an inversion, T falls in this way from 400 m.
- Situations: A (T at 400 m = −2 °C, ΔT = 6 °C, cap 1100 m), B (0 °C, 5 °C, 1400 m), C (−4 °C, 6 °C, 1200 m, dry air), D (8 °C, no inversion, humid from 700 m). In V2 the cap in B was 1420 m; it has been rounded to the 100 m slider step.
- Dew point: saturated, Td = T − 0.2 °C up to the cap, then 5 °C drier above it and drier still further up (0.15 °C per 10 m); raised: Td = T − 2.5 °C below 800 m; humid: T − 1.5 °C below 700 m, T − 0.2 °C above; dry: T − 6.5 °C at 400 m, increasing to T − 9.5 °C at 1800 m.
- Calculation step: 20 m. Lines are clipped to the −30…+10 °C axis.
What has changed since V2
- The 1 m elevation slider has been replaced by five stops: accuracy to the metre was illusory given the simplified model.
- The sliders for ΔT and the basin-floor temperature have been dropped: they are fixed in each situation because they did not change the conclusion. The upper limit of the cap and the humidity remain.
- The four metric tiles have been replaced by a readout that depends on step 1–3.
- The separate card comparing A and B has been replaced by two rows that are always visible next to the readout.
- Saving the profile in the browser has been dropped: there is nothing to remember, and the page stores nothing locally.
- The photograph from Równia (a hotlink to Wikimedia Commons) is not embedded: the page is meant to work offline, and the photograph is not synchronised with any other. The link to it is kept below.
- Kept: the formulae for T and Td, the 0.5 °C threshold, situations A–D, points A and B, the 1988 case and the source links.
Sources
The descriptions come from the V2 material. In this version none of the addresses below was reopened and their content was not checked.
- National Weather Service — What is a temperature inversion?: the definition of an inversion, night-time radiative cooling, the blocking of vertical mixing.
- National Weather Service — Radiation Fog: conditions for radiation fog to form in sheltered valleys.
- Urban, Migała, Pawliczek — Usłonecznienie Karkonoszy [Sunshine duration in the Giant Mountains]: observations from Śnieżka and Szrenica, including 21 September 1988 (according to V2).
- Karkonoski Park Narodowy — Zjawiska meteorologiczne Karkonoszy [Karkonosze National Park — Meteorological phenomena of the Giant Mountains]: local inversions and the sea of fog in the Jelenia Góra Basin (according to V2).
- Context photograph from V2, not embedded: ŠJů / Wikimedia Commons, licence CC BY-SA 3.0 (according to the caption in V2, to be checked).
The diagram on this page is our own illustration of the model, not a verified map or a measurement. Before heading into the Giant Mountains, check the announcements of the Karkonosze National Park (KPN), the mountain rescue service (GOPR) and the forecasts of the Institute of Meteorology and Water Management (IMGW-PIB).