Its not really calculated, its live information from people in those areas. There are numerous volunteers around you that collect weather data and send this information to the state that you live in and also to the local broadcasting companies. They report wind speed, direction, precipitation, temperature, barometric pressure, humidity and visibility.
The ones that I know of around me are automated. They are programmed to call in at pre-set intervals. Most visibility reports are from air traffic control towers where this information is vital to normal everyday operations of an airport.
Chat with our AI personalities
Visibility does not depend on speed.
It's approximately 1500m and is generally used in weather forecasts. In reality it varies slightly depending on the temperature and is calculated using the Hypsometric equation.
Means the business is online as well as a shop
If you can see it, it is visible. If you cannot it is not visible. Quite simple, really.
The mode reports that value that occurs most often.