Visibility meter

In meteorology, the following quantities are distinguished for visibility:

• Meteorological Optical Range (MOR) or meteorological day vision. This is an objective physical variable where the specific properties of the human eye and background brightness do not play a role.
• Perceived Visibility (VIS). This is the visually determined vision, in which the degree of darkness, expressed in background brightness and the presence of light sources do play a role. An observer can derive the MOR from this.
• Visual Range (VR). VR concerns the presentation of vision to users and must be based on fully defined specifications of the human eye, the luminous intensity of light sources and the background brightness.

Data

The data collected with the visibility meter can be found in various places:

• Rijkswaterstaat Waterinfo and Rijkswaterstaat Waterberichtgeving provide access to the meteorological data of Landelijk Meetnet Water (LMW) (the National Water Monitoring Network).
• The LMW also sends the data directly to the KNMI data portal.
• The Digital North Sea Alliance website provides access to meteorological data for a number of wind farms in the North Sea.

Customers and applications

Customers include wind farm operators, energy traders, Rijkswaterstaat, the KNMI, skippers of Crew Transfer Vessels (CTVs), major seaports, (commercial) shipping, the Coast Guard, incident organizations and recreationists.

The data is used for climatological research, maritime research and the development, calibration and validation of models.