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
Particulates or atmospheric particulate matter are microscopic particles of solid or liquid matter suspended in the air. The term aerosol commonly refers to the particulate/air mixture, as opposed to the particulate matter alone. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation that adversely affect human health, in ways additional to direct inhalation.
PM2.5 and PM10 compared with a human hair in a graphic from the Environmental Protection Agency
Excavator (a type of heavy equipment commonly used at construction sites and roadworks) demolishing the remnants of the pre-war Postal Train 0880Station (Dworzec Pocztowy) at Jerozolimskie Avenue, Poland
Particulates in the air causing shades of orange, yellow, pink, and grey in Mumbai during sunset
Air pollution measurement station in Emden, Germany