The autoignitiontemperature or kindling point of a substance is the lowest temperature at which it will Spontaneous combustion spontaneously ignite in a normal atmosphere without an external source of ignition, such as a flame or spark. This temperature is required to supply the activation energy needed for combustion . The temperature at which a chemical will ignite decreases as the pressure increases or oxygen concentration increases. It is usually applied to a combustible fuel mixture. Autoignition temperatures of liquid chemicals are typically measured using a 500 mL flask placed in a temperature controlled oven in accordance with the procedure described in ASTM E659. ref E659 78 Reapproved 2000 , Standard Test Method for AutoignitionTemperature of Liquid Chemicals , ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428 2959 ref When measured for plastics, autoignitiontemperature can also be measured under elevated pressure and at 100 oxygen concentration. The resulting value is used as a predictor of viability for high oxygen service. The main testing standard for this is ASTM G72. ref S. Grynko, Material Properties Explained 2012 , ISBN 1 4700 7991 7, p. 46. ref Autoignition equation The time math t ig , math it takes for a material to reach its autoignitiontemperature math T ig , math when exposed to a heat flux math q , math is given by the following equation math t ig left frac pi 4 right left k rho c right left frac T ig T o q right 2 math ref Principles of Fire ... AutoignitionTemperature of 100 Common Organic Chemical Compounds . Fire DEFAULTSORT AutoignitionTemperature Category Chemical properties Category Fire ar ast Temperatura ... specific heat capacity J kg K of the material of interest. math T o , math is the temperature, in kelvins, the material starts at or the temperature of the bulk material , and math q , math is the heat ... q right math should be squared. Autoignition point of selected substances Temperatures vary widely in the literature ... more details
pp move indef About the thermodynamic property Temperature disambiguation Image MonthlyMeanT.gif thumb .... Temperature is a physical property of matter that quantitatively expresses the common notions of heat hot and cold . Objects of low temperature are cold, while various degrees of higher temperatures ... temperature to bodies of lower temperature, at a rate that increases with the temperature difference and the thermal conductivity . No heat will be exchanged between bodies of the same temperature such bodies are said to be in thermal equilibrium . The temperature of a substance typically varies ... to the mean kinetic energy of its constituent particles. Formally, temperature is defined as the derivative of the internal energy with respect to the entropy . Quantitatively, temperature is measured with thermometers , which may be calibration calibrated to a variety of Temperature conversion formulas temperature scales . Image Thermally Agitated Molecule.gif 280px thumb right Thermal vibration of a segment of protein alpha helix . The amplitude of the vibrations increases with temperature. Temperature plays an important role in all fields of natural science, including physics , geology , chemistry , atmospheric sciences and biology . Use in science File Annual Average Temperature Map.jpg thumb 400px Annual mean temperature around the world Many physical properties of materials ... , solubility , vapor pressure , and electrical conductivity depend on the temperature. Temperature .... This is one reason why the human body has several elaborate mechanisms for maintaining the temperature ... consequences. Temperature also determines the thermal radiation emitted from a surface. One application ... electrically heated to a temperature at which significant quantities of visible light are emitted. Temperature scales see also Scale of temperature Most of the world uses the Celsius scale C for most temperature measurements. Citation needed date March 2012 It has the same incremental scaling as the Kelvin ... more details
Temperature range may refer to Atmospheric temperature An aspect of Climate Climate classification climate classification Diurnal temperature variation Operating temperatureTemperature Thermoregulation Disambiguation ... more details
wiktionarypar melting temperature Melting temperature may refer to Melting point , the temperature at which a substance changes from solid to liquid state. DNA melting temperature , the temperature at which a DNA double helix dissociates into single strands. disambig ... more details
wiktionarypar temperatureTemperature is a physical property of a system that underlies the common notions of hot and cold. Closely related are Thermodynamic temperature Color temperature Effective temperature Normal human body temperature The term may also refer to Noise temperature , a measure of the noise of an electronic component. Temperature meat , or doneness, a description of how thoroughly cooked a cut of meat is Temperature song Temperature song , a song by Sean Paul Temperature Zion I song Temperature Zion I song Temperature , a song by Blaque from Blaque Out Temperature , a song by Little Walter Albums Little Walter See also Lookfrom Temperature disambig ca Temperatura desambiguaci de Temperatur Begriffskl rung la Temperatura discretiva lt Temperat ra reik m s pl Temperatura ujednoznacznienie ... more details
Temperature Rising may refer to Temperature Rising album Temperature Rising , a studio album by Thai singer Tata Young Temperatures Rising , an American television situation comedy Temperature s Rising , an album by rock group Loverboy Temperature s Rising Mobb Deep song Temperature s Rising a single by Mobb Deep off of the 1995 album The Infamous disambig ... more details
Refimprove date April 2009 Orphan date February 2009 The permissive temperature is the temperature at which a temperature sensitive mutant gene product takes on a normal, functional phenotype. ref http www.biology online.org dictionary Permissive temperature ref When a temperature sensitive mutant is grown in a permissive condition, the mutant mutated gene product behaves normally meaning that the phenotype isn t observed , even if there is a mutant allele present. This results in the survival of the cell or organism, as if it were a wild type strain. In contrast, the nonpermissive temperature or restrictive temperature is the temperature at which the mutant phenotype is observed. Most temperature sensitive mutations affect proteins, and are recessive and cause loss of protein function at the non permissive temperature. The permissive temperature is one at which the protein typically can fold properly, or remain properly folded. References Reflist Category Temperature Category Cell biology Category Biology terminology biochemistry stub ... more details
Apparent temperature is the general term for the perceived outdoor temperature, caused by the combined effects of air temperature , relative humidity and wind speed . The Heat index measures the effect of humidity on the perception of temperature. In humid conditions, the air feels hotter than it actually is, because of the reduction in evaporation of perspiration . The Wind chill measures the effect of wind speed on the perception of temperature. In windy conditions, the air feels cooler than it actually is, because of the increase in evaporation of perspiration. The Wet Bulb Globe Temperature WBGT combines the effects of radiation, humidity, temperature and wind speed on the perception of temperature. It is not often used as the resulting figure is very location specific eg cloud cover and or wind shielding . Category Temperature ... more details
Comparison US standard atmosphere 1962.svg Atmospheric temperature is a measure of temperature at different levels of the Earth s atmosphere . It is governed by many factors, including insolation incoming solar radiation , humidity and altitude . When discussing surface temperature , the annual atmospheric temperature range at any geographical location depends largely upon the type of biome , as measured by the K ppen climate classification . Temperature versus height File EarthAtmosphereBig.jpg thumb 50px right main lapse rate In the Earth s atmosphere, temperature varies greatly at different heights relative to the Earth s surface. The coldest temperatures lie near the mesopause , an area approximately convert 85 km mi abbr on to convert 100 km mi abbr on above the surface. In contrast, some of the warmest temperatures can be found in the thermosphere , which receives strong ionizing radiation at the level of the Van Allen radiation belt . Temperature varies as one moves vertically upwards from the Earth s Surface. Global temperature seealso Schumann resonances Global temperature The concept of a global temperature is commonly used in climatology , and denotes the average temperature of the Earth based on surface ref cite web last Hansen first James E. title GISS Surface Temperature Analysis GISTEMP url http data.giss.nasa.gov gistemp work National Aeronautic and Space Administration publisher Goddard Institute for Space Studies accessdate 1 September 2011 authorlink James Hansen ref , near surface or troposphere tropospheric measurements. These temperature record s and measurements are typically acquired using the satellite temperature record satellite or instrumental temperature record ground instrumental temperature thermometer measurements , then usually compiled using ... proxy climate proxy data . See also Atmospheric thermodynamics Brightness temperature Emissivity Emissivity ... Category Atmospheric thermodynamics Category Climate Category Thermodynamics Category Temperature ... more details
Temperature cycling or temperature cycle is the process of cycling through two temperature extremes, typically at relatively high rates of change. It is an environmental Stress testing stress test used in evaluating product Reliability engineering reliability as well as in manufacturing to catch early term, latent defects by inducing failure through thermal Fatigue material fatigue . External links http www.motorola.com testservices temperature1.html Temperature Testing Motorola http www.jedec.org download search 22a104d.pdf Temperature Cycling JEDEC Standard No. 22 A104D http www.siliconfareast.com TCT.htm Temperature Cycle Test SiliconFarEast.com http www.siliconfareast.com faq tc life.htm Equivalent Life of Temperature Cycle Testing SiliconFarEast.com Category Reliability engineering ... more details
Unreferenced date February 2008 Transition temperature is the temperature at which a material changes from one crystal state Allotropy allotrope to another. For example, when Allotropes of sulfur List of allotropes and forms rhombic sulfur is heated above 96 C it changes form into monoclinic sulfur. When cooled below 96 C it reverts to rhombic sulfur. In the case of ferroelectric or ferromagnetic crystals a transition temperature may be known as the Curie temperature . Commented out information that seems inconsistent with the primary definition Transition temperature is the temperature at which a solid changes State of matter state , either becoming softer when Heat heated or more brittle when cooled. Transition temperature is the temperature above and below which solubility changes in a noticeably different way. On a graph the transition temperature is deduced by the intersection of two lines each of which have a different gradient. See also Crystal system Category Crystallography Chemistry stub ... more details
Equilibrium temperature may refer to Thermal equilibrium , for questions of heat transfer. Gliese 581 g , for temperatures of extrasolar planets. disambig ... more details
The vibrational temperature is commonly used in thermodynamics , to simplify certain equations. It has units of temperature and is defined as math theta vib frac h nu k B math br where math k B math is Boltzmann s constant The vibrational temperature is used commonly when finding the vibrational partition function . References http www.chem.arizona.edu salzmanr 480b statt02 statt02.html Statistical thermodynamics University Arizona See also Rotational temperature Rotational spectroscopy Vibrational spectroscopy Infrared spectroscopy Spectroscopy Category Atomic physics Category Molecular physics ... more details
Multiple issues orphan January 2011 unreferenced January 2011 Temperature strips are flexible, often disposable visual indicator s used to quickly and easily take and monitor surface temperature . They are used in laboratory, food and beverage, hospital and home applications, and often use a gradient color scheme to communicate a safe or out of tolerance condition. They also see use in racing when teams need to monitor the temperature of certain parts of the car, such as when the rear suspension has hot exhaust blowing over it. DEFAULTSORT Temperature Strip Category Thermometers ... more details
In thermodynamics, the Boyle temperature is defined as the temperature for which the second virial coefficient , math B 2 T math vanishes, i.e. math B 2 T 0 math . It is at this temperature that the attractive forces and the repulsive forces acting on the gas particles balance out. Since higher order virial coefficients are generally much smaller than the second coefficient, the gas tends to behave as an ideal gas over a wider range of pressures when the temperature reaches the Boyle temperature. In any case, when the pressures are low, the second virial coefficient will be the only relevant one because the remaining concern terms of higher order on the pressure. We then have math dZ dp 0 math at math p 0 math , where Z is the compressibility factor . Defination in simple language Boyle Temperature It is the temperature at which a non ideal gas behaves like an ideal gas. At Boyle temperature ,Z 1 and B 0 gives T b a Rb Category Thermodynamics de Boyle Temperatur es Temperatura de Boyle ... more details
Junction temperature is the highest temperature of the actual semiconductor in an electronic device. In operation it is higher than case temperature and the temperature of the part s exterior. The difference is equal to the amount of heat transferred from the junction to case multiplied by the junction to case thermal resistance . Maximum junction temperature is specified in a part s datasheet and is used when calculating the necessary case to ambient thermal resistance for a given power dissipation. This in turn is used to select an appropriate heat sink if necessary. An estimation of the chip junction temperature, T sub J sub , can be obtained from the following equation T sub J sub T sub A sub R sub JA sub P sub D sub where T sub A sub ambient temperature for the package C R sub JA sub junction to ambient thermal resistance C W P sub D sub power dissipation in package W DEFAULTSORT Junction temperature Category Semiconductors engineering stub zh ... more details
38.7.JPG thumb right A medical clinical thermometer showing the temperature of 38.7 C Attempts of standardized temperature measurement have been reported as early as 170 AD by Galen Claudius Galenus . ref name quinn cite book author T. J. Quinn year 1983 title Temperature publisher Academic Press ... in the 17th century. Early devices to measure temperature were called thermoscope s. The first ... The development of today s thermometer s and temperature scales began in the early 18th century, when ... and the Kelvin scale. Technologies Many methods have been developed for measuring temperature. Most of these rely on measuring some physical property of a working material that varies with temperature. One of the most common devices for measuring temperature is the mercury in glass thermometer glass ..., which acts as the working fluid. Temperature increase causes the fluid to expand, so the temperature ... so that one can read the temperature simply by observing the level of the fluid in the thermometer ... standpoint, is the gas thermometer . Other important devices for measuring temperature include Thermocouple s Thermistor s Resistance Temperature Detector RTD Pyrometer Langmuir probe s for electron temperature of a Plasma physics plasma Infrared Other thermometer s One must be careful when measuring temperature to ensure that the measuring instrument thermometer, thermocouple, etc. is really the same temperature as the material that is being measured. Under some conditions heat from the measuring instrument can cause a temperature gradient, so the measured temperature is different from the actual temperature of the system. In such a case the measured temperature will vary not only with the temperature of the system, but also with the heat transfer properties of the system. An extreme ... windy conditions than calm conditions even though the temperature is the same. What is happening is that the wind ... temperature for the same ambient temperature. The theoretical basis for thermometers is the zeroth ... more details
In fluid dynamics , the bulk temperature , or the average fluid bulk temperature , is a convenient reference point for evaluating properties related to convective heat transfer , particularly in applications related to flow in pipe material pipes and duct HVAC ducts . The concept of the bulk temperature is that adiabatic mixing of the fluid from a given cross section of the duct will result in some equilibrium temperature that accurately reflects the average temperature of the moving fluid, more so than a simple average like the film temperature . ref Kreith, Frank, and Bohn, Mark S. Principles of Heat Transfer, Sixth Edition. Brooks Cole Pacific Grove, CA, 2001. ref References references Category Fluid dynamics Category Thermodynamics Category Heat transfer fluiddynamics stub ... more details
Unreferenced date November 2006 The Excitation Temperature math T rm ex math often called the spin temperature for the 21 cm line is defined for a population of particles via the Boltzmann factor . It satisfies math frac n rm u n rm l frac g rm u g rm l exp frac Delta E k T rm ex , math where n sub u sub and n sub l sub represent the number of particles in an upper e.g. excited and lower e.g. ground state, and g sub u sub and g sub l sub their statistical weights respectively. Thus the excitation temperature is the temperature at which we would expect to find a system with this ratio of level populations. However it has no actual physical meaning except when in local thermodynamical equilibrium. The excitation temperature can even be negative for a system with inverted levels such as a maser . DEFAULTSORT Excitation Temperature Category Temperature Category Physics ... more details
Unreferenced stub auto yes date December 2009 Homologous temperature expresses the temperature of a material as a fraction of its melting point temperature using the Kelvin scale . For example, the homologous temperature of lead at room temperature is approximately 0.50 T sub H sub T T sub mp sub 298K 601K 0.50 . Solder T sub mp sub 183 C 456K at 0.85T sub mp sub or 115 C 388K , would thus be expected to have comparable properties to copper T sub mp sub 1085 C 1358K at 0.85T sub mp sub or 881 C 1154K . In electronics applications, where circuits typically operate over a 55 C to 125 C range, eutectic tin lead Sn63 solder is working at 0.48T sub mp sub to 0.87T sub mp sub . The upper temperature is high relative to the melting point from this we can deduce that solder will have limited mechanical strength as a bulk material and significant Creep deformation creep under stress. This is borne out by its comparatively low values for tensile strength, shear strength and modulus of elasticity. Citation needed date April 2009 Copper, on the other hand, has a much higher melting point, so foils are working at only 0.16T sub mp sub to 0.29T sub mp sub , and their properties are little affected by temperature. DEFAULTSORT Homologous Temperature Category Units of temperature Physics stub Measurement stub ... more details
In heat transfer and fluid dynamics , the film temperature math T f math is an approximation to the temperature of a fluid inside a convection boundary layer . It is calculated as the arithmetic mean of the temperature at the surface of the solid boundary wall math T w math and the free stream temperature math T infty math ref Incropera & DeWitt Fundamentals of Heat and Mass Transfer , 4th Ed ref math T f frac T w T infty 2 math The film temperature is often used as the temperature at which fluid properties are calculated when using Prandtl number , Nusselt number , Reynolds number or Grashof number to calculate a heat transfer coefficient , because it is a reasonable first approximation to the temperature within the convection boundary layer. Somewhat confusing terminology may be encountered in relation to boilers and heat exchangers, where the same term is used to refer to the limit hot temperature of a fluid in contact with a hot surface. ref http www.paratherm.com tipsheets tipsheet fluid life film temperature.asp Film Temperature ref ref http www.multitherm.com technical articles bulk film temp impact.html Bulk and Film Temperatures ref References references Category Fluid dynamics Category Heat transfer it Temperatura di film pt Temperatura de pel cula ... more details
In thermodynamics and fluid mechanics , stagnation temperature is the temperature at a stagnation point in a fluid flow. At a stagnation point the speed of the fluid is zero and all of the kinetic energy has been converted to internal energy adiabatically and is added to the local Enthalpy static enthalpy . In incompressible flow incompressible fluid flow , and in isentropic compressible flow , the stagnation temperature is equal to the total temperature at all points on the streamline leading to the stagnation point. ref Van Wylen and Sonntag, Fundamentals of Classical Thermodynamics , section 14.1 ref See gas dynamics . Derivation Adiabatic Stagnation temperature can be derived from the First Law of Thermodynamics . Applying the Steady Flow Energy Equation ref Van Wylen and Sonntag, Fundamentals of Classical Thermodynamics , equation 5.50 ref and ignoring the work, heat and gravitational ... capacity ratio specific heat at constant pressure math T 0 , math stagnation or total temperature at a stagnation point math T , math temperature also known as static temperature at any other point on the stagnation ... of both temperature and density. However, invoking the common assumption of a calorically perfect gas, enthalpy can be converted directly into temperature as given above, which enables one to define a stagnation temperature in terms of the more fundamental property, stagnation enthalpy. Stagnation properties e.g. stagnation temperature, stagnation pressure are useful in jet engine performance calculations. In engine operations, stagnation temperature is often called total air temperature . A bimetallic thermocouple is often used to measure stagnation temperature, but allowances for thermal ... the term stagnation temperature to indicate the maximum achievable collector temperature with a stagnant fluid no motion , an ambient temperature of 30C, and incident solar radiation of 1000W m ... context. See also Stagnation point Stagnation pressure Total air temperature References Van Wylen ... more details
The convective temperature CT or T sub c sub is the approximate temperature that air near the surface must reach for cloud formation without mechanical lift. In such case, cloud base begins at the convective condensation level CCL , whilst with mechanical lifting, condensation begins at the lifted condensation level LCL . Convective temperature is important to forecasting thunderstorm development. See also Atmospheric convection Atmospheric thermodynamics Meteorological variables climate stub Category Severe weather and convection Category Atmospheric thermodynamics ja ... more details
The Krafft temperature also known as Krafft point , or critical micelle temperature is the minimum temperature at which surfactant s form micelle s. Below the Krafft temperature, there is no value for the critical micelle concentration CMC , i.e., micelles cannot form. The Krafft temperature is a point of phase change below which the surfactant remains in crystalline form, even in aqueous solution. Surfactants in such a crystalline state will only solubilize and form micelles if another surfactant assists it in overcoming the forces that keep it crystallized, or if the temperature increases, thus causing entropy to have a stronger force and encouraging the crystalline structure to break apart. The Krafft point is named after German chemist Friedrich Krafft . Structural Effects Surfactants are usually composed of a hydrocarbon chain and a polar head group. Increasing the length of the hydrocarbon chain increases the Krafft temperature because it improves Van der Waals force Van der Waals forces. External links http goldbook.iupac.org K03415.html IUPAC Gold book Krafft temperature chem stub Category Colloidal chemistry Category Physical chemistry de Krafft Punkt it Temperatura di Krafft nl Krafft temperatuur ja ... more details
The potential temperature of a Air parcel parcel of fluid at pressure math P math is the temperature ... math P 0 math , usually 1000 millibars. The potential temperature is denoted math theta math and, for air ... absolute temperature in K of the parcel, math R math is the gas constant of air, and math ... s equation. Contexts The concept of potential temperature applies to any stratified fluid. It is most ... that air temperature drops as one climbs a mountain and water temperature can increase with depth in very deep ocean trenches and within the ocean mixed layer . When potential temperature is used instead, these apparently unstable conditions vanish. Comments Potential temperature is a more dynamically important quantity than the actual temperature. This is because it is not affected by the physical ... and warm as it descends on the other side but the potential temperature will not change in the absence ... to as dry adiabatic . Since parcels with the same potential temperature can be exchanged without work or heating being required, lines of constant potential temperature are natural flow pathways. Under almost all circumstances, potential temperature increases upwards in the atmosphere, unlike actual temperature which may increase or decrease. Potential temperature is conserved for all dry ... very close to being dry adiabatic . Potential temperature is a useful measure of the static stability of the unsaturated atmosphere. Under normal, stably stratified conditions, the potential temperature .... If the potential temperature decreases with height, math frac partial theta partial z 0 math ... of decreasing potential temperature with height are uncommon, except while vigorous convection is underway or during periods of strong insolation . Situations in which the equivalent potential temperature ... potential temperature is conserved under adiabatic or isentropic air motions, in steady, adiabatic flow lines or surfaces of constant potential temperature act as Streamlines, streaklines, and pathlines ... more details
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