Lithometeors

MH0017

Haze

Haze is a suspension in the air of extremely small, dry particles invisible to the naked eye and sufficiently numerous to give the air an opalescent appearance (WMO, 2017).

Lithometeors

MH0018

Polluted Air

Polluted air is air containing dust, smoke, micro-organisms or gases different from those from which it would normally be composed (WMO, 1992).

Alternative definition: Polluted air is air which contains gases and particles emitted to the atmosphere by a variety of human activities and natural sources, or formed in the atmosphere, that at critical levels have harmful effects on human health, animals, plants and ecosystems, or reduce visibility and corrode materials, buildings and cultural heritage sites (UNEP, no date).

Lithometeors

MH0019

Sand haze

Sand haze is haze caused by the suspension in the atmosphere of small sand or dust particles, raised from the ground prior to the time of observation by a sandstorm or dust storm (WMO, 1992).

Lithometeors

MH0020

Smoke

Smoke is a suspension in the air of small particles produced by combustion (WMO, 2017).

Lithometeors

MH0014

Black Carbon (Brown Clouds)

Black carbon refers to the absorbing components of soot, often defined using elemental carbon and some condensed organics. Black carbon is an important part of the combustion product commonly referred to as soot. Black carbon in indoor environments is largely due to cooking with biofuels such as wood, dung and crop residue. Outdoors, it is due to fossil fuel combustion (diesel and coal), open biomass burning (associated with deforestation and crop residue burning), and cooking with biofuels (Ramanathan and Carmichael, 2008).

Lithometeors

MH0015