In meteorology, visibility is the measure of the distance at which an object or light can be clearly discerned. It depends on the transparency of the surrounding air and as such, it is unchanging no matter the ambient light level or time of day. It is reported within surface weather observations and METAR code either in meters or statute miles, depending upon the country. Visibility affects all forms of traffic: roads, railways, sailing and aviation.
Airplane flying into clouds on descent for landing
Foggy morning road
On clear days, Tel Aviv's skyline is visible from the Carmel mountains, 80 km north
From the summit of Mount Summano (1296 m Vicenza Italy), it is possible to see (dark blue sky line) the Tuscan-Emilian Apennines and Mount Cimone (2165 m Modena Italy) in good visibility. The distance is about 180 km. Note the fog present throughout the Po Valley in the lower layers.
Haze is traditionally an atmospheric phenomenon in which dust, smoke, and other dry particulates suspended in air obscure visibility and the clarity of the sky. The World Meteorological Organization manual of codes includes a classification of particulates causing horizontal obscuration into categories of fog, ice fog, steam fog, mist, haze, smoke, volcanic ash, dust, sand, and snow. Sources for particles that cause haze include farming, traffic, industry, windy weather, volcanic activity and wildfires.
Seen from afar and depending on the direction of view with respect to the Sun, haze may appear brownish or bluish, while mist tends to be bluish grey instead. Whereas haze often is considered a phenomenon occurring in dry air, mist formation is a phenomenon in saturated, humid air. However, haze particles may act as condensation nuclei that leads to the subsequent vapor condensation and formation of mist droplets; such forms of haze are known as "wet haze".
Haze over the Mojave Desert from a brush fire in Santa Barbara, California, seen as the Sun descends on the 2016 June solstice, allows the Sun to be photographed without a filter.
Bushfire haze in Sydney, Australia
Haze as smoke pollution over the Mojave from fires in the Inland Empire, June 2016, demonstrates the loss of contrast to the Sun, and the landscape in general.
Haze causing red sky, due to the scattering of light on smoke particles, also known as Rayleigh scattering during Mexico's forest fire season