Humidity is the concentration of water vapour present in the air. Water vapour, the gaseous state of water, is invisible to the human eye. Humidity indicates the likelihood for dew, or fog to be present; the amount of water vapour needed to achieve saturation increases as the temperature increases. As the temperature of a parcel of air decreases it will reach the saturation point without adding or losing water mass; the amount of water vapour contained within a parcel of air can vary significantly. For example, a parcel of air near saturation may contain 28 grams of water per cubic metre of air at 30 °C, but only 8 grams of water per cubic metre of air at 8 °C. Three primary measurements of humidity are employed: absolute and specific. Absolute humidity describes the water content of air and is expressed in either grams per cubic metre or grams per kilogram. Relative humidity, expressed as a percentage, indicates a present state of absolute humidity relative to a maximum humidity given the same temperature.

Specific humidity is the ratio of water vapor mass to total moist air parcel mass. Humidity plays an important role for surface life. For animal life dependent on perspiration to regulate internal body temperature, high humidity impairs heat exchange efficiency by reducing the rate of moisture evaporation from skin surfaces; this effect can be calculated using a heat index table known as a humidex. Absolute humidity is the total mass of water vapor present in mass of air, it does not take temperature into consideration. Absolute humidity in the atmosphere ranges from near zero to 30 grams per cubic metre when the air is saturated at 30 °C. Absolute humidity is the mass of the water vapor, divided by the volume of the air and water vapor mixture, which can be expressed as: A H = m H 2 O V n e t; the absolute humidity changes as air pressure changes, if the volume is not fixed. This makes it unsuitable for chemical engineering calculations, e.g. in drying, where temperature can vary considerably.

As a result, absolute humidity in chemical engineering may refer to mass of water vapor per unit mass of dry air known as the humidity ratio or mass mixing ratio, better suited for heat and mass balance calculations. Mass of water per unit volume as in the equation above is defined as volumetric humidity; because of the potential confusion, British Standard BS 1339 suggests avoiding the term "absolute humidity". Units should always be checked. Many humidity charts are given in g/kg or kg/kg; the field concerned with the study of physical and thermodynamic properties of gas–vapor mixtures is named psychrometrics. The relative humidity of an air-water mixture is defined as the ratio of the partial pressure of water vapor in the mixture to the equilibrium vapor pressure of water over a flat surface of pure water at a given temperature: ϕ = p H 2 O p H 2 O ∗ Relative humidity is expressed as a percentage. Relative humidity is an important metric used in weather forecasts and reports, as it is an indicator of the likelihood of precipitation, dew, or fog.

In hot summer weather, a rise in relative humidity increases the apparent temperature to humans by hindering the evaporation of perspiration from the skin. For example, according to the Heat Index, a relative humidity of 75% at air temperature of 80.0 °F would feel like 83.6 °F ±1.3 °F. Specific humidity is the ratio of the mass of water vapor to the total mass of the air parcel. Specific humidity is equal to the mixing ratio, defined as the ratio of the mass of water vapor in an air parcel to the mass of dry air for the same parcel; as temperature decreases, the amount of water vapor needed to reach saturation decreases. As the temperature of a parcel of air becomes lower it will reach the point of saturation without adding or losing water mass. A device used to measure humidity is called a hygrometer. A humidistat is a humidity-triggered switch used to control a dehumidifier. There are various devices used to regulate humidity. Calibration standards for the most accurate measurement include the gravimetric hygrometer, chilled mirror hygrometer, electrolytic hygrometer.

The gravimetric method, while the most accurate, is cumbersome. For fast and accurate measurement the chilled mirror method is effective. For process on-line measurements, the most used sensors nowadays are based on capacitance measurements to measure relative humidity with internal conversions

Enrique Ortiz de Landázuri Izarduy, born 11 August 1967, is a Spanish singer-songwriter. He has been described as "by far, the most international star of Spanish rock." Bunbury was born in Zaragoza, Spain. He got involved in music in the early 1980s, making his debut in a high school band called Apocalipsis, played along with Proceso Entrópico. In 1984, Bunbury joined. After adopting the nickname of Bunbury, taken from the Oscar Wilde stage play The Importance of Being Earnest, the musician founded the band Héroes del Silencio, becoming a major number in the Hispanic rock scene; the band broke up in 1996 and Bunbury started his solo career in 1997 with an electro-rock album, Radical Sonora with his new band: Copi, Del Moran, Ramon Gacias and former Héroes del Silencio guitarist Alan Boguslavsky. Known for reinventing himself, Bunbury released in 1999 the album Pequeño, which sounded different from anything he did before, his band suffered changes, Boguslavsky was replaced by Rafa Dominguez, the new faces, Ana Belén Estaje, Luis Miguel Romero, Javier Iñigo, Javier Garcia Vega & Antonio Ríos in the metal instruments.

This band was known as the "Huracán Ambulante" and recorded with Bunbury the rest of his solo discography. In 2005, after 8 years together, Bunbury dissolved the band and recorded a new album in 2006 with Nacho Vegas. In 2007, Héroes del Silencio agreed to participate in a 10 concert exclusive worldwide tour in ten cities around the world called "Tour 2007" to celebrate the 20th anniversary of their first performances and it has been 10 years since their disbanding in 1996; the first concert took place in Guatemala City on 15 September, followed by Buenos Aires, Mexico, Los Angeles, Mexico City, Spain, Seville and Valencia, Spain which closed the'07 Tour. The solo career of Bunbury unlike Héroes del Silencio has been different in the musical sound, keeping the essence of rock, experimenting with various rhythms from electronic music and Middle Eastern music in the early stages of his solo career, to cabaret music, blues and tango, to salsa, milonga and cumbia in one of his last works which honors Latin America.

According to La Banda Elastica, "Rock gods exist... and Enrique Bunbury belongs among them." He is known for his powerful, operatic voice which can range from F2-A5 with the ability to hit C3. Bunbury is a baritone. In 2019 Bunbury was honored with the Icon Award at the 2019 SESAC Latina Music Awards. A documentary directed by Alexis Morante will be released in 2016 named El camino más largo, the film chronicles the 2010 tour Bunbury did of the United States, he is a vegan. Pep Blay Enrique Bunbury. Lo demás es silencio. Barcelona, 2007, Plaza & Janés. 448 pages, Spanish. ISBN 978-84-01-30551-1. Enrique Bunbury Official Web Site Official pages on social media sites

Allan Sparrow was a Canadian political activist and long standing city councillor in Toronto. He was instrumental in stopping the Spadina Expressway, setting up civilian oversight of the Toronto Police, promoting cycling in Toronto and gay rights, he was instrumental in the cancellation of a proposed bridge to the Toronto Island Airport. Born in Vancouver, British Columbia, Allan Sparrow moved to Toronto in 1967 with his wife Sue Sparrow, he became an activist, joining the movement to stop the Spadina Expressway, a controversial expressway that would have been built through residential neighborhoods of central Toronto. Sparrow served on the Toronto City Council for three terms, from 1974 until 1980 under the mayoralty of David Crombie. While at Council, he formed the Toronto Cycling Committee, he opposed the old guard of councillors whose support he believed could be bought by developers for block-busting development of inner city neighborhoods. He formed the Citizens Independent Review of Police Activities, which sought to open up investigations into police misconduct.

At the time, there was no civilian oversight of the police force. He gave up his council seat in an attempt to give the seat to an gay candidate in the 1980 election. After his term on Council, he became an information-technology consultant, he promoted IT investment in Canada for the federal government. Sparrow became a key player in the formation of Reform Toronto in 1988, a municipal watchdog group that published a newspaper, "The Badger", distributed door-to-door to target neighbourhoods; the group endorsed seven reform-minded candidates in the 1988 municipal election of which five were elected, helping to create the first majority of reform candidates in Toronto history. Whitney Smith, another key member of the group, said that "Reform Toronto's success was influenced by Allan's strategic thinking and encouragement of his colleagues."In 1997 he retired as a consultant to the Toronto Islands, in 2001 he returned to politics as the founder of Community Air, a volunteer association opposed to expansion of the Toronto Island Airport.

The group was successful in stopping a planned bridge to the airport and Sparrow stepped down as leader of Community Air. Despite the bridge cancellation, expansion of the island airport caused him and his wife to move in 2007 to Stratford, Ontario to move away from the airport, he died on April 2008 from colorectal cancer in London, Ontario. Federal NDP leader Jack Layton praised Sparrow as "a good friend and leader" who "inspired a generation of reform-minded progressives with ahead-of-his-time thinking on environment issues"