Pressure as exerted by particle collisions inside a closed container.

Thermodynamics
Branches Classical · Statistical · Chemical Equilibrium / Non-equilibrium Thermofluids
Laws Zeroth · First · Second · Third
Systems State: Equation of state Ideal gas · Real gas Phase of matter · Equilibrium Control volume · Instruments Processes: Isobaric · Isochoric · Isothermal Adiabatic · Isentropic · Isenthalpic Quasistatic · Polytropic Free expansion Reversibility · Irreversibility Endoreversibility Cycles: Heat engines · Heat pumps Thermal efficiency
System properties Property diagrams Intensive and extensive properties State functions: Temperature / Entropy (intro.) † Pressure / Volume † Chemical potential / Particle no. † († Conjugate variables) Vapor quality Reduced properties Process functions: Work · Heat
Material properties Specific heat capacity  Failed to parse (Missing texvc executable; please see math/README to configure.): c= Failed to parse (Missing texvc executable; please see math/README to configure.): T Failed to parse (Missing texvc executable; please see math/README to configure.): \partial S Failed to parse (Missing texvc executable; please see math/README to configure.): N Failed to parse (Missing texvc executable; please see math/README to configure.): \partial T Compressibility  Failed to parse (Missing texvc executable; please see math/README to configure.): \beta=- Failed to parse (Missing texvc executable; please see math/README to configure.): 1 Failed to parse (Missing texvc executable; please see math/README to configure.): \partial V Failed to parse (Missing texvc executable; please see math/README to configure.): V Failed to parse (Missing texvc executable; please see math/README to configure.): \partial p Thermal expansion  Failed to parse (Missing texvc executable; please see math/README to configure.): \alpha= Failed to parse (Missing texvc executable; please see math/README to configure.): 1 Failed to parse (Missing texvc executable; please see math/README to configure.): \partial V Failed to parse (Missing texvc executable; please see math/README to configure.): V Failed to parse (Missing texvc executable; please see math/README to configure.): \partial T Property database
Equations Carnot's theorem Clausius theorem Fundamental relation Ideal gas law Maxwell relations Table of thermodynamic equations
Potentials Free energy · Free entropy Internal energy Failed to parse (Missing texvc executable; please see math/README to configure.): U(S,V) Enthalpy Failed to parse (Missing texvc executable; please see math/README to configure.): H(S,p)=U+pV Helmholtz free energy Failed to parse (Missing texvc executable; please see math/README to configure.): A(T,V)=U-TS Gibbs free energy Failed to parse (Missing texvc executable; please see math/README to configure.): G(T,p)=H-TS
History and culture Philosophy: Entropy and time · Entropy and life Brownian ratchet Maxwell's demon Heat death paradox Loschmidt's paradox Synergetics History: General · Heat · Entropy · Gas laws Perpetual motion Theories: Caloric theory · Vis viva Theory of heat Mechanical equivalent of heat Motive power Publications: "An Experimental Enquiry Concerning ... Heat" "On the Equilibrium of Heterogeneous Substances" "Reflections on the Motive Power of Fire" Timelines of: Thermodynamics · Heat engines Art: Maxwell's thermodynamic surface Education: Entropy as energy dispersal
Scientists Daniel Bernoulli Sadi Carnot Benoît Paul Émile Clapeyron Rudolf Clausius Hermann von Helmholtz Constantin Carathéodory Pierre Duhem Josiah Willard Gibbs James Prescott Joule James Clerk Maxwell Julius Robert von Mayer William Rankine John Smeaton Georg Ernst Stahl Benjamin Thompson William Thomson, 1st Baron Kelvin John James Waterston
v t e

Pressure (the symbol: p) is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure (also spelled gage pressure)^[a] is the pressure relative to the local atmospheric or ambient pressure.

Definition[link]

Pressure is the effect of a force applied to a surface. Pressure is the amount of force acting per unit area. The symbol of pressure is p.^[b][1]

Formula[link]

Mathematically:

Failed to parse (Missing texvc executable; please see math/README to configure.): p = \frac{F}{A}\ \mbox{or}\ p = \frac{dF_n}{dA}

where:

p is the pressure,

F is the normal force,

A is the area of the surface area on contact

Pressure is a scalar quantity. It relates the vector surface element (a vector normal to the surface) with the normal force acting on it. The pressure is the scalar proportionality constant that relates the two normal vectors:

Failed to parse (Missing texvc executable; please see math/README to configure.): d\mathbf{F}_n=-p\,d\mathbf{A} = -p\,\mathbf{n}\,dA

The minus sign comes from the fact that the force is considered towards the surface element, while the normal vector points outward.

It is incorrect (although rather usual) to say "the pressure is directed in such or such direction". The pressure, as a scalar, has no direction. It is the force given by the previous relationship to the quantity that has a direction, not the pressure. If we change the orientation of the surface element, the direction of the normal force changes accordingly, but the pressure remains the same.

Pressure is transmitted to solid boundaries or across arbitrary sections of fluid normal to these boundaries or sections at every point. It is a fundamental parameter in thermodynamics, and it is conjugate to volume.

Units[link]

Mercury column

The SI unit for pressure is the pascal (Pa), equal to one newton per square meter (N/m² or kg·m⁻¹·s⁻²). This special name for the unit was added in 1971;^[2] before that, pressure in SI was expressed simply as N/m².

Non-SI measures such as pounds per square inch and bars are used in some parts of the world, primarily in the United States of America. The cgs unit of pressure is the barye (ba), equal to 1 dyn·cm⁻² or 0.1 Pa. Pressure is sometimes expressed in grams-force/cm², or as kg/cm² and the like without properly identifying the force units. But using the names kilogram, gram, kilogram-force, or gram-force (or their symbols) as units of force is expressly forbidden in SI. The technical atmosphere (symbol: at) is 1 kgf/cm² (14.223 psi).

Since a system under pressure has potential to perform work on its surroundings, pressure is a measure of potential energy stored per unit volume measured in J·m⁻³, related to energy density.

Some meteorologists prefer the hectopascal (hPa) for atmospheric air pressure, which is equivalent to the older unit millibar (mbar). Similar pressures are given in kilopascals (kPa) in most other fields, where the hecto- prefix is rarely used. The inch of mercury is still used in the United States. Oceanographers usually measure underwater pressure in decibars (dbar) because an increase in pressure of 1 dbar is approximately equal to an increase in depth of 1 meter.

The standard atmosphere (atm) is an established constant. It is approximately equal to typical air pressure at earth mean sea level and is defined as follows:

standard atmosphere = 101,325 Pa = 101.325 kPa = 1,013.25 hPa.

Because pressure is commonly measured by its ability to displace a column of liquid in a manometer, pressures are often expressed as a depth of a particular fluid (e.g., centimeters of water, mm or inches of mercury). The most common choices are mercury (Hg) and water; water is nontoxic and readily available, while mercury's high density allows a shorter column (and so a smaller manometer) to be used to measure a given pressure. The pressure exerted by a column of liquid of height h and density ρ is given by the hydrostatic pressure equation p = ρgh. Fluid density and local gravity can vary from one reading to another depending on local factors, so the height of a fluid column does not define pressure precisely. When millimeters of mercury or inches of mercury are quoted today, these units are not based on a physical column of mercury; rather, they have been given precise definitions that can be expressed in terms of SI units. One mmHg (millimeter of mercury) is equal to one torr. The water-based units still depend on the density of water, a measured, rather than defined, quantity. These manometric units are still encountered in many fields. Blood pressure is measured in millimeters of mercury in most of the world, and lung pressures in centimeters of water are still common.

Underwater divers use the metre sea water (msw or MSW) and foot sea water (fsw or FSW) units of pressure, and these are the standard units for pressure guages used to measure pressure exposure in diving chambers and personal decompression computers. A msw is defined as 0.1 bar, and is not the same as a linear metre of depth, and 33.066 fsw = 1 atm.^[3] Note that the pressure conversion from msw to fsw is different from the length conversion: 10 msw = 32.6336 fsw, while 10 m = 32.8083 ft

Gauge pressure is often given in units with 'g' appended, e.g. 'kPag' or 'psig', and units for measurements of absolute pressure are sometimes given a suffix of 'a', to avoid confusion, for example 'kPaa', 'psia'. However, the US National Institute of Standards and Technology recommends that, to avoid confusion, any modifiers be instead applied to the quantity being measured rather than the unit of measure^[4] For example, "P_g = 100 psi" rather than "P = 100 psig".

Differential pressure is expressed in units with 'd' appended; this type of measurement is useful when considering sealing performance or whether a valve will open or close.

Presently or formerly popular pressure units include the following:

• atmosphere (atm)
• manometric units:
  • centimeter, inch, and millimeter of mercury (torr)
  • Height of equivalent column of water, including millimeter (mm H₂O), centimeter (cm H₂O), meter, inch, and foot of water
• customary units:
  • kip, ton-force (short), ton-force (long), pound-force, ounce-force, and poundal per square inch
  • ton-force (short), and ton-force (long) per square inch
  • fsw (feet sea water) used in Underwater diving, particularly in connection with diving pressure exposure and decompression
• non-SI metric units:
  • bar, decibar, millibar
    • msw (metres sea water), used in Underwater diving, particularly in connection with diving pressure exposure and decompression
  • kilogram-force, or kilopond, per square centimeter (technical atmosphere)
  • gram-force and tonne-force (metric ton-force) per square centimeter
  • barye (dyne per square centimeter)
  • kilogram-force and tonne-force per square meter
  • sthene per square meter (pieze)

Examples[link]

As an example of varying pressures, a finger can be pressed against a wall without making any lasting impression; however, the same finger pushing a thumbtack can easily damage the wall. Although the force applied to the surface is the same, the thumbtack applies more pressure because the point concentrates that force into a smaller area. Pressure is transmitted to solid boundaries or across arbitrary sections of fluid normal to these boundaries or sections at every point. Unlike stress, pressure is defined as a scalar quantity.

Another example is of a common knife. If we try to cut a fruit with the flat side it obviously won't cut. But if we take the thin side, it will cut smoothly. The reason is that the flat side has a greater surface area (less pressure) and so it does not cut the fruit. When we take the thin side, the surface area is reduced and so it cuts the fruit easily and quickly. This is one example of a practical application of pressure.

The gradient of pressure is called the force density. For gases, pressure is sometimes measured not as an absolute pressure, but relative to atmospheric pressure; such measurements are called gauge pressure. An example of this is the air pressure in an automobile tire, which might be said to be "220 kPa/32 psi", but is actually 220 kPa/32 psi above atmospheric pressure. Since atmospheric pressure at sea level is about 100 kPa/14.7 psi, the absolute pressure in the tire is therefore about 320 kPa/46.7 psi. In technical work, this is written "a gauge pressure of 220 kPa/32 psi". Where space is limited, such as on pressure gauges, name plates, graph labels, and table headings, the use of a modifier in parentheses, such as "kPa (gauge)" or "kPa (absolute)", is permitted. In non-SI technical work, a gauge pressure of 32 psi is sometimes written as "32 psig" and an absolute pressure as "32 psia", though the other methods explained above that avoid attaching characters to the unit of pressure are preferred.^[5]

Gauge pressure is the relevant measure of pressure wherever one is interested in the stress on storage vessels and the plumbing components of fluidics systems. However, whenever equation-of-state properties, such as densities or changes in densities, must be calculated, pressures must be expressed in terms of their absolute values. For instance, if the atmospheric pressure is 100 kPa, a gas (such as helium) at 200 kPa (gauge) (300 kPa [absolute]) is 50% denser than the same gas at 100 kPa (gauge) (200 kPa [absolute]). Focusing on gauge values, one might erroneously conclude the first sample had twice the density of the second one.

Scalar nature[link]

In a static gas, the gas as a whole does not appear to move. The individual molecules of the gas, however, are in constant random motion. Because we are dealing with an extremely large number of molecules and because the motion of the individual molecules is random in every direction, we do not detect any motion. If we enclose the gas within a container, we detect a pressure in the gas from the molecules colliding with the walls of our container. We can put the walls of our container anywhere inside the gas, and the force per unit area (the pressure) is the same. We can shrink the size of our "container" down to an infinitely small point, and the pressure has a single value at that point. Therefore, pressure is a scalar quantity, not a vector quantity. It has magnitude but no direction sense associated with it. Pressure acts in all directions at a point inside a gas. At the surface of a gas, the pressure force acts perpendicular (at right angle) to the surface.

A closely related quantity is the stress tensor σ, which relates the vector force F to the vector area A via

Failed to parse (Missing texvc executable; please see math/README to configure.): \mathbf{F}=\mathbf{\sigma A}\,

This tensor may be divided up into a scalar part (pressure) and a traceless tensor part shear. The shear tensor gives the force in directions parallel to the surface, usually due to viscous or frictional forces. The stress tensor is sometimes called the pressure tensor, but in the following, the term "pressure" will refer only to the scalar pressure.

According to the theory of general relativity, pressure increases the strength of a gravitational field (see stress-energy tensor) and so adds to the mass-energy cause of gravity. This effect is unnoticeable at everyday pressures but is significant in neutron stars, although it has not been experimentally tested.^[6]

Types[link]

Fluid pressure[link]

Fluid pressure is the pressure at some point within a fluid, such as water or air.

Fluid pressure occurs in one of two situations:

1. an open condition, called "open channel flow"
   1. the ocean, or
   2. swimming pool, or
   3. the atmosphere.
2. a closed condition, called closed conduits
   1. water line, or
   2. gas line.

Pressure in open conditions usually can be approximated as the pressure in "static" or non-moving conditions (even in the ocean where there are waves and currents), because the motions create only negligible changes in the pressure. Such conditions conform with principles of fluid statics. The pressure at any given point of a non-moving (static) fluid is called the hydrostatic pressure.

Closed bodies of fluid are either "static", when the fluid is not moving, or "dynamic", when the fluid can move as in either a pipe or by compressing an air gap in a closed container. The pressure in closed conditions conforms with the principles of fluid dynamics.

The concepts of fluid pressure are predominantly attributed to the discoveries of Blaise Pascal and Daniel Bernoulli. Bernoulli's equation can be used in almost any situation to determine the pressure at any point in a fluid. The equation makes some assumptions about the fluid, such as the fluid being ideal^[7] and incompressible.^[7] An ideal fluid is a fluid in which there is no friction, it is inviscid,^[7] zero viscosity.^[7] The equation is written between any two points in a system that contain the same fluid.

Failed to parse (Missing texvc executable; please see math/README to configure.): \frac{p}{\gamma}+\frac{v^2}{2g}+z=\frac{p}{\gamma}+\frac{v^2}{2g}+z

^[8]

where:

p = pressure of the fluid

γ = ρg = density·acceleration of gravity = specific weight of the fluid.^[7]

v = velocity of the fluid

g = acceleration of gravity

z = elevation

Failed to parse (Missing texvc executable; please see math/README to configure.): \frac{p}{\gamma}

= pressure head

Failed to parse (Missing texvc executable; please see math/README to configure.): \frac{v^2}{2g}

= velocity head

Applications[link]

• Artesian well
• Blood pressure
• Hydraulic head
• Plant cell turgidity
• Pythagorean cup

Explosion or deflagration pressures[link]

Explosion or deflagration pressures are the result of the ignition of explosive gases, mists, dust/air suspensions, in unconfined and confined spaces.

Negative pressures[link]

While pressures are, in general, positive, there are several situations in which negative pressures may be encountered:

• When dealing in relative (gauge) pressures. For instance, an absolute pressure of 80 kPa may be described as a gauge pressure of −21 kPa (i.e., 21 kPa below an atmospheric pressure of 101 kPa).
• When attractive forces (e.g., van der Waals forces) between the particles of a fluid exceed repulsive forces. Such scenarios are generally unstable since the particles will move closer together until repulsive forces balance attractive forces. Negative pressure exists in the transpiration pull of plants, and is used to suction water even higher than the ten meters that it rises in a pure vacuum.
• The Casimir effect can create a small attractive force due to interactions with vacuum energy; this force is sometimes termed "vacuum pressure" (not to be confused with the negative gauge pressure of a vacuum).
• Depending on how the orientation of a surface is chosen, the same distribution of forces may be described either as a positive pressure along one surface normal, or as a negative pressure acting along the opposite surface normal.
• In the cosmological constant.

Stagnation pressure[link]

Stagnation pressure is the pressure a fluid exerts when it is forced to stop moving. Consequently, although a fluid moving at higher speed will have a lower static pressure, it may have a higher stagnation pressure when forced to a standstill. Static pressure and stagnation pressure are related by the Mach number of the fluid. In addition, there can be differences in pressure due to differences in the elevation (height) of the fluid. See Bernoulli's equation (note: Bernoulli's equation only applies for incompressible, inviscid flow).

The pressure of a moving fluid can be measured using a Pitot tube, or one of its variations such as a Kiel probe or Cobra probe, connected to a manometer. Depending on where the inlet holes are located on the probe, it can measure static pressures or stagnation pressures.

Surface pressure[link]

There is a two-dimensional analog of pressure – the lateral force per unit length applied on a line perpendicular to the force.

Surface pressure is denoted by π and shares many similar properties with three-dimensional pressure. Properties of surface chemicals can be investigated by measuring pressure/area isotherms, as the two-dimensional analog of Boyle's law, πA = k, at constant temperature.

Failed to parse (Missing texvc executable; please see math/README to configure.): \pi = \frac{F}{l}.

Pressure of an ideal gas[link]

In an ideal gas, molecules have no volume and do not interact. Pressure varies linearly with temperature, volume, and quantity according to the ideal gas law,

Failed to parse (Missing texvc executable; please see math/README to configure.): P=\frac{nRT}{V}

where:

P is the absolute pressure of the gas

n is the amount of substance

T is the absolute temperature

V is the volume

R is the ideal gas constant.

Real gases exhibit a more complex dependence on the variables of state.^[9]

Vapor pressure[link]

Vapor pressure is the pressure of a vapor in thermodynamic equilibrium with its condensed phases in a closed system. All liquids and solids have a tendency to evaporate into a gaseous form, and all gases have a tendency to condense back to their liquid or solid form.

The atmospheric pressure boiling point of a liquid (also known as the normal boiling point) is the temperature at which the vapor pressure equals the ambient atmospheric pressure. With any incremental increase in that temperature, the vapor pressure becomes sufficient to overcome atmospheric pressure and lift the liquid to form vapor bubbles inside the bulk of the substance. Bubble formation deeper in the liquid requires a higher pressure, and therefore higher temperature, because the fluid pressure increases above the atmospheric pressure as the depth increases.

The vapor pressure that a single component in a mixture contributes to the total pressure in the system is called partial vapor pressure.

Liquid pressure or pressure at depth[link]

Used with liquid columns of constant density or at a depth within a substance (example: pressure at 20 km depth in the Earth).

Failed to parse (Missing texvc executable; please see math/README to configure.): P=\rho gh

where:

P is Pressure

g is gravity at the surface of overlaying material

ρ is density of liquid or overlaying material

h is height of liquid or depth within a substance

See also[link]

Underwater diving portal

Notes[link]

References[link]

External links[link]

• Introduction to Fluid Statics and Dynamics on Project PHYSNET
• Pressure being a scalar quantity
• Online pressure converter for 15 different pressure units

Nadia Ali
Nadia Ali in 2011
Background information
Birth name	Nadia Ali
Born	(1980-08-03) August 3, 1980 (age 31) Libya
Origin	Queens, New York, U.S.
Genres	Electronic dance music, trance, house
Occupations	Singer-songwriter
Instruments	Vocals
Years active	2001–present
Labels	Smile in Bed
Associated acts	iiO, Armin van Buuren, Morgan Page, Avicii, Starkillers, Sultan & Ned Shepard
Website	nadiaali.com

Nadia Ali (Urdu: نادیہ علی; born August 3, 1980) is a Pakistani American singer-songwriter, born in Libya and raised in Queens, New York. She gained attention as the frontwoman and songwriter of the band iiO, after their 2001 hit "Rapture" reached No. 2 on the UK Singles Chart.^[1] The song also charted across several countries in Europe.^[2] Their 2006 single, "Is It Love?", reached the top of the Billboard Hot Dance Club Play Chart.^[3]

After embarking on a solo career in 2005, Ali became successful as an oft-requested vocalist in electronic dance music. She released her debut album Embers in 2009. Critics praised her unique songwriting, which combined electronica with ballads, Eastern and acoustic music. Three singles from the album reached the top-ten of the Billboard Hot Dance Club Play Chart, including the No. 1 hit, "Love Story".^[4][5][6] The song was also nominated at the 25th International Dance Music Awards at the Winter Music Conference, while "Fantasy" was nominated for a Grammy award.^[7][8]

In 2010, she released a remix compilation titled Queen of Clubs Trilogy to mark her decade-long career as a singer-songwriter. "Rapture" was re-released as the only single from the compilation and the song was once again a chart success in Europe.^[9] Ali released the single "Pressure" with Starkillers and Alex Kenji in 2011, which became a club and festival anthem and received an International Dance Music Award.^[10] She has also collaborated with several notable producers and DJs, such as Armin van Buuren, Schiller, BT and John Creamer & Stephane K. Ali is currently working on her second studio album titled Phoenix, which is due to be released in 2012.

Life and career[link]

1980–2005: Early life and iiO[link]

Nadia Ali was born in Libya to Pakistani parents in 1980. The family relocated when she was five years old and she was subsequently raised in Queens, New York.^[11][12] An eight year old Ali used any opportunity she could get to sing after a friend heard her humming a Madonna song at school and complimented her.^[13] While continuing singing as a hobby and for the thrill of performing and receiving no formal vocal training, she had also started writing poems and songs for her friends by the time she was 15.^[11] As a teenager her interest in dance music developed after visiting nightclubs in Manhattan and inspired her to dream that she would one day be featured on one of the records playing in the club.^[14]

Ali started working in the New York offices of Versace when she was 17, where she attracted attention by singing at the Christmas parties.^[11] A colleague from Versace introduced her to producer Markus Moser, who was looking for a female singer to collaborate on some of his original production for a girl group in Germany.^[13] The two teamed up with Moser working on production, while Ali wrote the lyrics and vocals for the songs.^[15] Her first song was the single "Rapture", which she wrote in 30 minutes based on an encounter with an Australian nightclub patron.^[16] A demo of the song was first played at the New York club Twilo in 2001 and received early support from influential DJ Pete Tong who played the demo on his show on BBC Radio 1. The song eventually became an Ibiza favourite after support from prominent DJ's such as Sasha, Danny Tenaglia and Sander Kleinenberg during the summer season.^[17] Released in late 2001 by Ministry of Sound, the single became a commercial success peaking at No. 2 on UK Singles Chart and Billboard's Hot Dance Club Play Chart, while charting in several countries in Europe.^[1][2][3] The success of "Rapture", Ali said, caused the formation of iiO as the music they were initially working on was quite different from dance music and were asked to come up with a project name to promote the single.^[18] They originally named themselves Vaiio after the Sony VAIO laptop Ali used to write the lyrics on.^[2] The duo toured internationally and released several more singles, including "At the End", "Runaway", "Smooth", and "Kiss You". Their first studio album, Poetica followed in 2005.^[4]

Ali left the group in 2005 to pursue a solo career, while Moser continued to release iiO material featuring her on vocals. Most notably, these releases include the 2006 single "Is It Love?", which reached No. 1 in America on the Billboard Hot Dance Club Play Chart,^[3] the 2007 remix album Reconstruction Time: The Best Of iiO Remixed^[4] and the 2011 studio album Exit 110.^[4] When asked about her decision to pursue a solo career, she said her time with iiO was a great learning experience but she decided to leave because she didn't want to restrict herself to one style of music but explore her creativity and also to have the freedom to collaborate with others artists.^[19]

Her decision to pursue a career as a singer was not initially encouraged by her Pakistani parents who were academically inclined and wanted her to pursue a more stable career. She has said since then they have evolved and are one of her biggest supporters.^[12] Speaking of her identity as a Pakistani and Muslim woman, she has said it is very important to her to set an example that they are able to contribute positively and capable of taking their career into their own hands. Explaining further, she said that she feels it as her responsibility to any women who are sometimes stereotyped to show that they can contribute to arts or any professional field.^[11] Her ethnicity, she has stated, has been an advantage and helped her stand out in the entertainment industry.^[20] She has said that over the years, she has met South Asian women who have told her that her story has inspired them to pursue something they loved.^[21]

[edit] 2006–09: Embers

Nadia Ali performing at Avalon, Boston in 2006

Ali started working on her debut solo album soon after leaving iiO, a process which took her four years. She attributed the delay to her busy tour schedule and the fact that she was still learning and "trying to establish her identity as a songwriter and co-producer".^[18][22] Her first solo release was the 2006 single, "Who is Watching?", a collaboration with Dutch DJ Armin van Buuren, which appeared on his album Shivers.^[23] She has described "Who is Watching?" as one of her most meaningful songs, the song described one's struggle to reach the top, only to realise once one is there how lonely it is and how one has forgotten their priorities and the important people in their life.^[24] This was followed by "Something to Lose" in 2006, a duet with singer-songwriter Rosko, produced by John Creamer & Stephane K and released by Ultra Records. The track was licensed to Roger Sanchez's Release Yourself, Vol. 5, as well as Sharam Tayebi of Deep Dish for his Global Underground debut Dubai.^[25][26]

In June 2008, she released "Crash and Burn", the first single from her solo album. The single became a club success peaking at No. 6 on Billboard's Hot Dance Club Play Chart.^[5] She released the second single, "Love Story" from the as-yet untitled album in February 2009. It topped Billboard Hot Dance Club Play Chart in April 2009 and was nominated for the Best Progressive/House Track at the 2010 International Dance Music Awards at the Winter Music Conference.^[6][7] Ali was featured on MTV Iggy in March 2009, where she recorded three live acoustic videos, performing "Rapture", "Crash and Burn" and "Love Story".^[27]

The third single "Fine Print" was released in July 2009. Ali announced that the single preceded the release of her debut solo album Embers.^[28] The single peaked at No. 4 on Billboard's Hot Dance Club Play Chart.^[29] Embers was released in September 2009. Co-produced by Sultan & Ned Shepard, Alex Sayz and Scott Fritz, Ali self-released the album on her own label, Smile in Bed Records.^[22] Embers generally received positive reviews, Chase Gran from About.com called it a "well rounded, gourmet album with impressive songs".^[30] Gail Navarro from Racket magazine complimented Ali on her songwriting saying, "It wasn’t just her sultry sound mixed in together with that enchanting singing voice; her songwriting got me hook, line and sinker".^[31] Speaking about the self-release of the album, she has cited her creative independence and the pressure of deadlines as the main reasons why she created her own record label.^[32][33] She chose to release her singles and albums digitally citing the nature of the electronic music audience with the listener choosing to click a button and getting music instantly and the traditional method of distribution deals in the United States.^[32]

Ali released two collaborations in 2009, the first "Better Run" with Tocadisco was released on his album TOCA 128.0 FM and "12 Wives In Tehran" with Serge Devant was released on his album Wanderer.^[34][35]

[edit] 2010–2011: Queen of Clubs Trilogy

Ali's first release in 2010 was the track "Try", a collaboration with German producer Schiller, chosen as the lead single from his album Atemlos, the music video premiered on YouTube in February 2010.^[36] In April 2010, Ali released "Fantasy", the fourth single from Embers. The track was chosen as a single by her fans after a poll conducted by Ali on her Facebook page.^[22] The music video for "Fantasy" was set to the Morgan Page remix, which served as a prologue to Ali's next project; Queen of Clubs Trilogy: The Best of Nadia Ali Remixed. Speaking about the project, Ali mentioned that she wanted a remix compilation, which spanned the 10 years of her career from her one-half as iiO, to her solo album and collaborations.^[37] Explaining the name of the concept, she said she wanted to incorporate her upbringing in Queens and the fact that her music is predominantly played in nightclubs.^[38] Using that inspiration, she decided to use the playing card "Queen of Clubs" as the title, portraying herself as the Queen, a move she described as "audacious" but something she felt she could prove because she had the substance.^[37] The package was broken into three releases: Ruby Edition (August 2010), Onyx Edition (October 2010) and Diamond Edition (December 2010). It featured collaborations with, and remixes by, Armin van Buuren, Gareth Emery and Avicii amongst several other prominent DJs and producers.^[39]

I think the fact that it (electronic dance music) is mostly male dominated makes females stand out that much more if they are driven enough. I believe anything is possible with hard work.

– Nadia Ali^[40]

With a decade-long career, MTV described Ali as one of the "enduring empresses" of electronic dance music and the Queen of Clubs Trilogy as "aptly titled".^[41] Noted for being the "definitive" and "unmistakable" voice of dance music, she is said to have "enriched" and "invigorated" the genre.^[21][42] Ali has went on to become an oft-requested collaborator by DJs and producers.^[22] She was praised for acquiring notability in a male and DJ-dominated genre where vocalists serve as supporting acts.^[40][43] In December 2010 she received her first Grammy nomination when the Morgan Page remix of "Fantasy" was nominated in the Best Remixed Recording, Non-Classical category.^[8]

Her first track with iiO, "Rapture" was re-released as a single from Queen of Clubs Trilogy with remixes by Tristan Garner, Gareth Emery and Avicii. A new music video for the track was shot based on the "Queen of Clubs" theme and released on January 24, 2011.^[44] The song peaked at No. 3 on the Romanian Top 100 chart, while charting in other European countries.^[9]

Nadia Ali performing at Armin Only in Poland

Throughout 2010, Ali's collaborations with DJs and producers were released. These included remixes of her upcoming collaboration "That Day" with Dresden and Johnston, which were released on compilation albums. The next, "The Notice" with Swiss duo Chris Reece was released on July 13 on all digital retailers.^[45] Ali was featured on the track "Feels So Good" on Armin van Buuren's fourth album Mirage. Released as the fifth single from the album, the song was voted as the Best Trance Track at the 27th International Dance Music Awards in the Best Trance Song category.^[10][46] She was also a featured guest on his Armin Only tour.^[12]

During 2011, Ali announced the release of collaborations with several DJs and producers. The first of these was "Call My Name" with the duo Sultan & Ned Shepard, released by Harem Records on February 9. "Call My Name" was a club success, charting at No. 5 on Billboard Hot Dance Club Play Chart.^[47] The second track "Pressure", a collaboration with Starkillers and Alex Kenji was released on February 15 by Spinnin' Records.^[48] The Alesso remix of "Pressure" became a club and festival anthem and received support from notable DJs such as Armin van Buuren, Tiesto, Swedish House Mafia and Calvin Harris and was voted the Best Progressive House Track at the 27th International Dance Music Awards.^[10][49]

In April, iiO released the studio album Exit 110, which featured Ali on vocals. She distanced herself from the album and stated she had no involvement in the project besides her vocals and words from nearly 10 years ago being used for the songs.^[50] She described it as "interesting" that there was new material featuring her released by iiO when she hadn't worked with Moser since 2005.^[19] She further said that she hadn't spoken with Moser since her departure and when asked whether the split of iiO was amicable, she refused to explain the circumstances surrounding the dissolution of the duo.^[19] On May 23, her next collaboration, "Free To Go" with Alex Sayz was released by Zouk Recordings.^[51] She was featured on Sander van Doorn's second studio album Eleve11 on the track "Rolling the Dice", a collaboration between van Doorn, Sidney Samson and her.^[52] Her next release was the single "Believe It" with the German duo Spencer & Hill, which was released on October 3 by Wall Recordings.^[53] She collaborated once again with Starkillers on the single "Keep It Coming", which was released on December 26 by Spinnin' Records.^[54]

[edit] 2012–present: Phoenix

As of November 2010, Ali had begun working on her second studio album.^[12] A music video for the lead single from the album, "When It Rains", was released on her YouTube channel on August 17 2011 with a release date to be announced.^[55] She attributed the delay in the release of the album once again on her busy touring schedule citing the demand to perform live particularly in the United States.^[56][57] However, beginning in February 2012 she took 40 days off to finalise the album, which she said would be titled Phoenix.^[56] She chose the name as an allusion to what she felt was a relaunch of her career.^[58] Explaining the creative process behind the album, she said she chose to work with a mix of international producers in an effort to combine the North American understanding of good songwriting with the European expertise in production to create a high energy dance album catered for her dance music fans.^[57][59] She said she had tried to bring together the DJs who she had released songs with in the last few years to make one cohesive compilation.^[58] The theme of the album, she elaborated, was trying to get the listener to understand the "artist personality" and the singer-songwriter behind the music.^[59]

Her first release in 2012 was "This Is Your Life", the fourth single from Swiss DJ EDX's album On The Edge.^[60] That was followed by "Carry Me", a collaboration with Morgan Page on his third studio album, In the Air.^[61] Her next release will be "Must Be The Love", the lead single from BT's upcoming eighth studio album, which was a collaboration between him, Arty and Ali.^[62]

Musical style and influences[link]

Ali is perhaps best known for her characteristic voice and vocal abilities.^[21][31][63] Reema Kumari Jadeja from MOBO described her work as "masterfully encapsulating euphoric and melancholic, Ali’s signature music style sees Eastern mystique caressed with intelligent electronica and fortified with soul".^[21] The songs on Embers were likened to Madonna's work in her prime and a "modern re-intepretation" of Stevie Nicks. Billboard praised her voice for having "too much life on its own".^[42][31][63] Ali has been influenced by an eclectic mix of artists, which she credits to her Eastern background and upbringing in Queens.^[18][33] She listed alternative, folk, Indian and Pakistani music as her biggest influences.^[16][18] Some of her vocal and songwriting influences, she said, were Stevie Nicks, Nusrat Fateh Ali Khan, Madonna, Sade and Bono.^[13][16][32]

	"Crash and Burn" (2008) noicon "Crash and Burn" combines Ali's signature music styles: Eastern, electronic and acoustic
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Her debut album was noted for a blend of electronica, acoustic and Middle Eastern melodies.^[30] Speaking about Embers, Ali said she did not want a typical dance record and chose to experiment, particularly with the number of ballads on the album.^[18] Meanwhile, her second album Phoenix, she said would be a more "high-energy" dance album, where while she maintained her characteristic vocal style, she also experimented with the musical style.^[58] She said while working on the album she was inspired and influenced by indie pop and the styles of Avicii, R3hab and Skrillex.^[58] Ali has collaborated with DJs from a broad range of genres and styles in electronic dance music. Some of the resulting work has been described as minimal trance,^[64] "sad disco"^[36] and "mainstream pop".^[45]

She has been praised for her songwriting, describing personal experiences with people, which "hit a powerful and striking chord" with the listener.^[31] Ali has said she almost always prefers to sing a song she has written herself and that the best songs are mostly written when they narrate a true account.^[13][14] The songs on Embers, Ali has stated, describe the relationships she has experienced and the emotions they have left behind.^[40] The song "Fantasy", she said, summed her up how she likes to be recognised, "an emotional songwriter who loves being a part of electronic music".^[22] Ali has said in the future she would like to focus more on production and songwriting and has written songs for Tocadisco, Avicii, Hardwell, Sultan & Ned Shepard, EDX and Pete tha Zouk.^[21][24]

Discography[link]

Studio albums

• Embers (2009)
• Phoenix (2012)

Compilations

• Queen of Clubs Trilogy: Ruby Edition (2010)
• Queen of Clubs Trilogy: Onyx Edition (2010)
• Queen of Clubs Trilogy: Diamond Edition (2010)

Awards and nominations[link]

References[link]