@Vihtahousu
Happy to hear that good news. Thank you for your feedback.

The ozone layer is the part of the Earth's atmosphere that has the most ozone in it.
It's the atmospheric layer within the stratosphere, extending from a height of c. 20 to c. 30 km (c. 12 to c. 18 mi). The ozone layer protects living things from the harmful radiation of the sun. It absorbs dangerous ultraviolet radiation from the sun and serves to maintain the temperature of the atmosphere.

A dobson unit is the most basic measure used in ozone research. One Dobson Unit (DU) is defined to be 0.01 mm thickness at STP (standard temperature and pressure). Ozone layer thickness is expressed in terms of Dobson Units, which measure what its physical thickness would be if compressed in the Earth's atmosphere. In those terms, it's very thin indeed. A normal range is 300 to 500 Dobson Units (3-5 mm), which translates to an eighth of an inch-basically two stacked pennies.

In space, it's best not to envision the ozone layer as a distinct, measurable band. Instead, think of it in terms of parts per million concentrations in the stratosphere (the layer six to 30 miles above the Earth's surface).

The unit is named after Gordon Dobson, one of the first scientists to investigate atmospheric ozone.

NASA uses a baseline value of 220 DU for ozone. This was chosen as the starting point for observations of the Antarctic ozone hole, since values of less than 220 Dobson units were not found before 1979. Also, from direct measurements over Antarctica, a column ozone level of less than 220 Dobson units is a result of the ozone loss from chlorine and bromine compounds.

Ozone depletion describes two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere (the ozone layer), and a much larger springtime decrease in stratospheric ozone around Earth's polar regions. The latter phenomenon is referred to as the ozone hole. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events.

The main cause of ozone depletion and the ozone hole is manufactured chemicals, especially manufactured halocarbon refrigerants, solvents, propellants and foam-blowing agents (chlorofluorocarbons (CFCs), HCFCs, halons), referred to as ozone-depleting substances (ODS). These compounds are transported into the stratosphere by wind after being emitted from the surface, mixing much faster than the molecules can settle. Once in the stratosphere, they release halogen atoms through photodissociation, which catalyze the breakdown of ozone (O3) into oxygen (O2). Both types of ozone depletion were observed to increase as emissions of halocarbons increased.

Ozone depletion and the ozone hole have generated worldwide concern over increased cancer risks and other negative effects. The ozone layer prevents most harmful UVB wavelengths of ultraviolet light (UV light) from passing through the Earth's atmosphere. These wavelengths cause skin cancer, sunburn and cataracts, which were projected to increase dramatically as a result of thinning ozone, as well as harming plants and animals. These concerns led to the adoption of the Montreal Protocol in 1987, which bans the production of CFCs, halons and other ozone-depleting chemicals.

@takumhara
Windy changed it from cloud base to ceiling, but it is running under the same name on Windy. So the ceiling means > 50% of sky covered by clouds, in aviation it is higher than 4 octas, so it can be BKN = Broken or OVC = Overcast, where BKN = 5-7 octas, OVC = 8/8 octas fully covered.

And to answer your qestion, this parameter gives the height of ceiling in meters (m) or feet (ft) above the level of the model (ECMWF) orography, so it is AGL.

Read the corresponding article of Ceiling:
https://confluence.ecmwf.int//display/FCST/43r1+new+parameters%3A+Ceiling

But be aware of it, because of the ECMWF model has a 9km resolution, so it's sampling the terrain with 9 km steps. If you are planning around mountainous areas, you can't rely on it, do not use it for planning in such areas.

@egruebel
There was a general bug in currents feature, but it was fixed.
Read the according thread about that bug:
https://community.windy.com/topic/7772/current-unavailable

Does your reported bug still exists?

@jsdhornby
I answered you here for the same question:
https://community.windy.com/topic/7582/windy-launches-observation-vs-forecast/36

@jsdhornby
That coloured area represents the observed temperature on the upper side and the dew point on the lower side measured by the weather station. And its colour is corresponding to its colour scale depending on its value.

You can note that the more closer these two lines (values) to each other, the more saturated is the air. Obviously when the two values are equal --> the air is 100% saturated in this case (it's depicted on windy as a very little gap between the two lines, but above the chart at the value indicator you can read 2 equal values). In this 100% saturated air, the air contains a lot of moisture and there exist a low visibility condition, due to the very high probability of fog creation, which can transform into a low level stratus cloud with the help of a little wind. So it can influences the developing weather phenomenas.

Anyway, the other 2 dashed lines represents the forecasted TEMP and DEW POINT, for that weather model, which you select at the bottom of the chart.

Or if you are thought about the starting pop up charts and not the weather stations' "observation vs forecast" charts, there the coloured area represents only the forecasted temperature, as you can see it below.

@PhileasFogg1905
Tomas corrected it. So it will appear on Windy soon (I think in the next update).

@dzuremar
I found some precipitation out of the radar ranges. Maybe does it the same projection error, or does it a range problem?

Europe High Pressure - Warm Front

https://www.windy.com/annotation/5c63c17dc4cbfc0014c6710c

I just tried it, It's cool!:)
(Btw I depicted the warm front by triangles by mistake, imagine it correctly with semi-circles..)

This image is licenced under Creative Commons licence and can be used/modified freely in any possible way

Create your own annotation at https://www.windy.com/annotate

@justinlimbo
Such things that are specified for example on the Wunderground website here in the "Personal Weather Station Installation Guide", such as: where to place it depending on the environment, at what height...etc. All of the criterias that are given standing for keep a standard predetermined accuracy. In case of these conditions are not met with the given criterias, it will lead to inaccuracy, and obviously these weather stations will not be reliable at all. (as @Tomber42 said in his reply)
Anyway I absolutely agree with @Tomber42 because it's trivial that most of people looking at weather stations to get precise and reliable observation informations.. such as for example the Airports' weather stations are mainly the most reliable stations in my opinion.. and I can totally trust in it (because of it has regular maintenances, and operates under strictly specified standards).

And it would be nice if the same trust could be presented in the PWS's in the future, but imho that will need some installation criterias in the side of Windy.

If Windy would like to make it reliable and a good information source (such as now the most of weather stations), I think they should make a "Personal Weather Station Installation Guide" too, or something similar to that (as Wunderground did..), so those people who reported their PWS's should make those configurations that are laid down in the "Installation Guide", and their PWS's will appear just after that on Windy site.

To my mind, it would be a good solution to the all "PWS's unreliability and real data measuring" questions.

Btw, I don't say that this is a bad thing, I like it really much, and this "Observation vs forecast" feature is really unique and useful. But I'm just wondering what will happen with the newly coming PWS feature on the map.. And I just got this idea that I wrote above.

This is not an offense from my side, these are only some thoughts of the questioned area and potential ideas for the predictable problems.

Anyway I trust in Windy team, you guys always make really invaluable and unique features with a nice and clean interface. Just do it guys, as you always do!:))