Explanations and Legend

• Cloud Work Function (CWF)

The The cloud work function (CWF) can be viewed as an indicator that if the cloud is likely to grow. The cloud here generally refers to cumulus since they are much more often produced by convection than other clouds

Unit: J/Kg

• Copertura Nuvole

Cloud cover refers to the fraction of the sky obscured by clouds when observed from a particular location; it is expressed either in eighths or in tenths. APanel adopts the same display mode as the station model on weather maps, which represents the cloud cover with a filled circle. This forecast may miss very low cloud and afternoon thunderstorms.

• Seeing

The astronomical seeing conditions on a given night at a given location describe how much the atmosphere of the Earth perturbs the images of stars as seen through a telescope. The seeing here is a reference to the best possible angular resolution which can be achieved by an optical telescope.

In the chart, seeing is scaled as followed:

Generally the actual seeing is slightly worse than the prediction, as of the contribution of the turbulence near the ground.

• Trasparency

The transparency here is an integrated measure of the extinction of sky objects. The extinction is generally caused by the moisture of atmosphere. In this forecast, both moisture and ozone are taken into account, but no industrial pollutants or aerosols (although they are big contributors for starlight extinction as well), because they are hard to be measured and predicted across the global by far.

The forecast of transparency is displayed by colors and in eighths; the symbol can be converted into values with the chart below.

(Unit: magnitude/air mass)

• Lifted Index

The lifted index (LI) is the temperature difference between an air parcel lifted adiabatically Tp(p) and the temperature of the environment Te(p) at a given pressure height in the troposphere (lowest layer where most weather occurs) of the atmosphere, usually 500 hPa (mb). When the value is positive, the atmosphere (at the respective height) is stable and when the value is negative, the atmosphere is unstable.

The forecast of instability is displayed by colors and in eighths as below:

LI can be scaled as followed:

• Darkness

The darkness here shows the visual limiting magnitude in zenith. It takes into account sun’s and moon’s position, moon phase, atmospheric moisture condition (transparency/starlight extinction), ozone thickness, and environmental conditions near the surface (temperature, humidity, etc.), but light pollution is not yet included.

• Vento

The wind forecast here shows the average wind direction and speed at a height of 10 meters above the ground. The line points to the direction where the wind is coming from.

The conversion table of Beaufort Class and different wind speed units is shown below.