Thunder is the sound caused by lightning. Depending on the distance from and nature of the lightning, it can range from a sharp, loud crack to a long, low rumble; the sudden increase in pressure and temperature from lightning produces rapid expansion of the air within and surrounding the path of a lightning strike. In turn, this expansion of air creates a sonic shock wave referred to as a "thunderclap" or "peal of thunder"; the d in Modern English thunder is epenthetic, is now found as well in Modern Dutch donder. In Latin the term was tonare "to thunder"; the name of the Nordic god Thor comes from the Old Norse word for thunder. The shared Proto-Indo-European root is *tón-r̥ or *tar- found Gaulish Taranis and Hittite Tarhunt; the cause of thunder has been the subject of centuries of speculation and scientific inquiry. Early thinking was that it was made by deities but the ancient Greek philosophers attributed it to natural causes, such as wind striking clouds and movement of air within clouds.

The Roman philosopher, Lucretius held. By the mid-19th century, the accepted theory was. In the 20th century a consensus evolved that thunder must begin with a shock wave in the air due to the sudden thermal expansion of the plasma in the lightning channel; the temperature inside the lightning channel, measured by spectral analysis, varies during its 50 μs existence, rising from an initial temperature of about 20,000 K to about 30,000 K dropping away to about 10,000 K. The average is about 20,400 K; this heating causes a rapid outward expansion, impacting the surrounding cooler air at a speed faster than sound would otherwise travel. The resultant outward-moving pulse is a shock wave, similar in principle to the shock wave formed by an explosion, or at the front of a supersonic aircraft. Experimental studies of simulated lightning have produced results consistent with this model, though there is continued debate about the precise physical mechanisms of the process. Other causes have been proposed, relying on electrodynamic effects of the massive current acting on the plasma in the bolt of lightning.

The shock wave in thunder is sufficient to cause property damage and injury, such as internal contusion, to individuals nearby. Thunder can rupture the eardrums of people nearby. If not, it can lead to temporary deafness. Vavrek et al. reported that the sounds of thunder fall into categories based on loudness and pitch. Claps are loud sounds containing higher pitches. Peals are sounds changing in loudness and pitch. Rolls are irregular mixtures of pitches. Rumbles are less loud, last for longer, of low pitch. Inversion thunder results when lightning strikes between cloud and ground occur during a temperature inversion. In an inversion, the air near the ground is cooler than the higher air. Within a temperature inversion, the sound energy is prevented from dispersing vertically as it would in a non-inversion and is thus concentrated in the near-ground layer. Cloud-ground lightning consist of two or more return strokes, from ground to cloud. Return strokes have greater acoustic energy than the first.

The most noticeable aspect of lightning and thunder is that the lightning is seen before the thunder is heard. This is a consequence of the much greater speed of light than of speed of sound. Sound in dry air is 343 m/s or 1,127 ft/s or 768 mph at 20 °C; this translates to 3 seconds per kilometre. A bright flash of lightning and an simultaneous sharp "crack" of thunder, a thundercrack, therefore indicates that the lightning strike was near. Close-in lightning has been described first as a clicking or cloth-tearing sound a cannon shot sound or loud crack/snap, followed by continuous rumbling; the early sounds are from the leader parts of lightning the near parts of the return stroke the distant parts of the return stroke. Thunderbolt Thunderstorm Brontophobia Castle Thunder sound effect Lightning List of thunder gods Mistpouffers Media related to Thunder at Wikimedia CommonsThe science of thunder Thunder: A Child of Lightning Wikibooks: Engineering Acoustics/Thunder acoustics

Irène Souka is a retired Greek EU official, from 2009 to January 2020 Director General of the Directorate-General for Human Resources and Security of the European Commission. Irène Souka graduated in law from 1971 to 1976 at the National and Kapodistrian University of Athens. Additional studies in criminology at the University of Cambridge and international law at the Vrije Universiteit Brussel followed. Souka joined the European Commission in 1980 in the Directorate-General for Translation as team leader in the Greek division, she moved to the Directorate-General for Competition in 1990, as assistant to the Director General and since 1994 as head of unit. Since 2000 she worked in the Directorate General for Personnel and Administration as head of unit, deputy director-general, Director-General. During her career as Director-General, she is reported to have resisted various attempts at modernisation of the European civil service, including the establishment in 2002 of the European Personnel Selection Office upon initiative of then-Commissioner Neil Kinnock.

He position as Director-General, as well as that of her husband Dominique Ristori, were extended in February 2018 with unanimous decision of the College of Commissioners, since both had passed the retirement age of 65. At the same meeting, the Commissioners appointed Martin Selmayr to the post of deputy secretary-general and directly of secretary-general of the European Commission. Selmayr's appointment procedure was condemned by both the European Parliament and the European Ombudsman, which concluded that the Consultative Committee on Appointments that evaluates and shortlists candidates for senior Commission jobs - of which Souka was a permanent member as Director general of human resources - had not followed its own rules of procedures, including by not publishing the vacancy for the posts. Together with Selmayr, she is reported to have stopped the mandatory rotation policy for high-level EU civil servants every 5 to 7 years, remaining herself in the top position for 11 years, while extending the same policy to middle management.

At the same time, she was pivotal in managing the shift of the European Commission towards reaching the target of 40% of women in management by 2020. In 2019 Souka was confirmed as Director-General by the new Commissioner for Budget and Human Resources, Johannes Hahn and prolonged until 31 January 2020, she retired on that date, after complaining with the cabinet of Commission President Ursula Von Der Leyen that she had received no information about the further extension of her employment with the Commission. "Offizieller Lebenslauf". Https://ec.europa.eu/. EU. Retrieved 2019-01-13. Politico Europe

A fan, or fanatic, sometimes termed aficionado or supporter, is a person, enthusiastically devoted to something or somebody, such as a celebrity or band, a sport or a sports team, a genre, a politician, a book, a movie or an entertainer synonymous with "supporter". Collectively, the fans of a particular object or person constitute its fandom, they may show their enthusiasm in a variety of ways, such as by promoting the object of their interest, being members of a fan club, holding or participating in fan conventions, or writing fan mail. They may engage in creative activities such as creating fanzines, writing fan fiction, making memes or drawing fan art. Merriam-Webster, the Oxford dictionary and other sources define "fan" as a shortened version of the word fanatic. Fanatic itself, introduced into English around 1550, means "marked by excessive enthusiasm and intense uncritical devotion", it comes from the Modern Latin fanaticus, meaning "insanely but divinely inspired". The word pertained to a temple or sacred place.

The modern sense of "extremely zealous" dates from around 1647. However, the term "fancy" for an intense liking of something, while being of a different etymology, coincidentally carries a less intense but somewhat similar connotation to "fanatic". Use of "the fancy" to mean avid sports enthusiasts emerged as an Americanism in the mid-19th C; the Dickson Baseball Dictionary cites William Henry Nugent's work asserting that it was derived from the fancy, a term referring to the fans of a specific hobby or sport from the early 18th century to the 19th to the followers of boxing. According to that theory, it was shortened to fance just to the homonym fans; the Great American Baseball Scrapbook attributes the term to Chris Von der Ahe, owner of the Saint Louis Brown Stockings in 1882. Von der Ahe sold tickets for 25 cents, hoping the many patrons would purchase his beer, he called the fanatics filling his stands "fans". Supporter is a synonym to "fan" that predates the latter term and is still used in British English to denote fans of sports teams.

However, the term "fan" has become popular throughout the English-speaking world, including the United Kingdom. The term supporter is used in a political sense in the United States, to a fan of a politician, a political party, a controversial issue. There are accounts of the word "fan" not coming from the word "fanatic." In the early days of baseball and up until the 1960s, it was proper for men to wear a coat and tie while the women wore a dress oftentimes with a hat. In the dog days of summer, the heat from wearing such clothes could become unbearable. Spectators would fan themselves so much with their programs, scorecards or actual hand fans so players couldn't see their faces; the players would speak amongst themselves with phrases like, "sure are a lot of fans out there today" or if there's a bad call or a exciting play or dramatic moment in a game, it could be common to hear a player say, "lotta noise coming from the fans today." Fans have a strong enough interest that some changes in their lifestyles are made to accommodate devotion to the focal object.

Fans have a desire for external involvement – they are motivated to demonstrate their involvement with the area of interest through certain behaviors. Fans have a "wish to acquire" material objects related to the area of interest, such as a baseball hit by a famous slugger or a used guitar pick from their musical hero; as well, some fans have a desire for social interaction with other fans. This again may take many forms, from casual conversation, e-mail, chat rooms, electronic mailing lists to regular face-to-face meetings such as fan club meetings and organized conventions. There are several groups of fans that can be differentiated by the intensity level of their level of involvement or interest in the hobby The likelihood for a subject of interest to be elevated to the level of fandom appears to be dictated by its complexity. Complexity allows further involvement of fans for a longer period of time because of the time needed to work the subject of interest'out.' It contributes to a greater sense of belonging because of the mental effort invested in the subject.

These fans will hold a crush on a major movie star, pop star, athlete or celebrity. The groupie is an example, a fan of a particular band or musician, who will follow them on concert tours; the degree of devotion to celebrities can range from a simple crush to the deluded belief that they have a special relationship with the star which does not exist. In extreme cases, this can lead to celebrity worship syndrome; this can switch to hatred of the loved celebrity, result in attempts at violent attacks, one notable incident being the death of Rebecca Schaeffer by a stalking fan in 1989. This is somewhat related to the concept of parasocial interaction where audiences develop one-sided relationships with media characters and celebrities. Not all the fans have a crush on their idols. There's fans who want to become their friends or respect an idol's relationship. In fact, there are fans. Gaming fans, or "gamers", are fans focused on playing non-sport games role-playing games, board games, miniature wargames, collectible card games or video games.

Music fans can differ somewhat from fans of particular musicians, in that they may focus on a genre of music. Many o