Haze

Haze is traditionally an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky. The World Meteorological Organization manual of codes includes a classification of horizontal obscuration into categories of fog, ice fog, steam fog, mist, haze, smoke, volcanic ash, dust, sand and snow. Sources for haze particles include farming (ploughing in dry weather), traffic, industry, and wildfires.

Seen from afar (e.g. approaching airplane) and depending upon the direction of view with respect to the sun, haze may appear brownish or bluish, while mist tends to be bluish-grey. Whereas haze often is thought of as a phenomenon of dry air, mist formation is a phenomenon of humid air. However, haze particles may act as condensation nuclei for the subsequent formation of mist droplets; such forms of haze are known as "wet haze."

The term "haze", in meteorological literature, generally is used to denote visibility-reducing aerosols of the wet type. Such aerosols commonly arise from complex chemical reactions that occur as sulfur dioxide gases emitted during combustion are converted into small droplets of sulphuric acid. The reactions are enhanced in the presence of sunlight, high relative humidity, and stagnant air flow. A small component of wet haze aerosols appear to be derived from compounds released by trees, such as terpenes. For all these reasons, wet haze tends to be primarily a warm-season phenomenon. Large areas of haze covering many thousands of kilometers may be produced under favorable conditions each summer.

Aria

An aria ([ˈaːrja]; Italian: air; plural: arie [ˈaːrje], or arias in common usage, diminutive form arietta [aˈrjetta]) in music was originally any expressive melody, usually, but not always, performed by a singer. The term became used almost exclusively to describe a self-contained piece for one voice, with or without orchestral accompaniment, normally part of a larger work. The typical context for arias is opera, but vocal arias also feature in oratorios and cantatas, sharing features of the operatic arias of their periods.

Origins of the term

The term, which derives from the Greek and Latin 'aer' (air) first appeared in relation to music in the 14th century when it simply signified a manner or style of singing or playing. By the end of the 16th century, the term 'aria' refers to an instrumental form (cf. Santino Garsi da Parma lute works, 'Aria del Gran Duca' ). By the early 16th century it was in common use as meaning a simple setting of strophic poetry; melodic madrigals, free of complex polyphony, were known as madrigale arioso.