Visibility
Clouds & visibility meteorological visibility horizontal visibility
Visibility describes how far away objects can still be distinguished through the air. Fog, precipitation and suspended particles can reduce it sharply.
Why the distance disappears
A tower is still where it always was, but now it is barely visible. Droplets or dust between us and the tower scatter and absorb light, reducing its contrast against the background. Meteorological visibility is usually given in metres or kilometres.
What a station actually measures
An automatic sensor measures scattering or loss of light in a small volume of air and derives an optical range. It does not spot the church tower across town for itself. A model estimates visibility from other weather variables.
Several things can reduce visibility
- Fog: Suspended droplets or ice crystals reduce visibility below one kilometre.
- Rain or snow: Dense precipitation can also sharply limit the view.
- Mist or haze: Moisture and fine particles reduce contrast.
Why your own view may differ
Fog is often patchy. The view may be clear in one direction and blocked by a fog bank in another. Glare and darkness also affect what a person can distinguish. Meteorological visibility is therefore not a guarantee that an obstacle can be spotted in time at that distance.