question: How, on a hot day, can the pavement temperature be hotter considerably hotter than the air/actual temperature?
comment: In addition to heating from the air, the pavement *also* absorbs infrared energy directly from sunlight. Thus it gets even hotter than the air.
passages: An urban heat island occurs where the combination of heat-absorbing infrastructure such as dark asphalt parking lots and road pavement and expanses of black rooftops, coupled with sparse vegetation, raises air temperature by 1 to 3 °C higher than the temperature in the surrounding countryside.
   Section::::Benefits.
  
  BULLET::::- Reduction in energy usage. Energy usage is reduced as local temperatures are cooled. Lower temperatures allow air conditioners to cool buildings with less energy. Temperature reductions attributed to increased pavement albedo in Los Angeles resulted in over $90 million per year in savings. Reflective pavement also reduces energy at night as they demand lower street light usage.
   All the above-mentioned results are for situations with no heating effects. A numerical model study have shown that, when a surface in a street canyons heats up, it changes the characteristics of the vortex flow. And heating of different surfaces; upwind wall, downwind wall, canyon floor, changes the vortex flow in different manners.
  
  Section::::Effects.:Air quality.
  
  The modification of temperature and wind by the presence of a street canyon, consequently affect the air quality inside the street canyon.
   Depending on the temperature at which it is applied, asphalt is categorized as hot mix, warm mix, or cold mix. Hot mix asphalt is applied at temperatures over 300 °F (150 °C) with a free floating screed. Warm mix asphalt is applied at temperatures of 200–250 °F (95–120 °C), resulting in reduced energy usage and emissions of volatile organic compounds. Cold mix asphalt is often used on lower-volume rural roads, where hot mix asphalt would cool too much on the long trip from the asphalt plant to the construction site.
   The second cause of heat islands is the low moisture content of paving and building materials. Such materials are watertight, so no moisture is available to dissipate the sun's heat through evaporation.
  
  Tree planting has been shown to significantly reduce temperatures in open, paved areas. In one study in Alabama, daytime summer temperatures of 120°F were recorded in the centre of a bare parking lot, whereas where a small island of trees was present, temperatures only reached 89°F. It also found that a further 1°F temperature reduction could be obtained for every additional canopy tree planted.
  
  Section::::Environmental considerations.:Land usage.
   BULLET::::- Improvement in air quality. A reduction in energy usage would lower greenhouse emissions and air pollution (dependent on electric power fuel mix). Lower temperatures would also slow chemical reactions that create smog. In 2007, Surabi Menon and Hashem Akbari estimated that an increase of global pavement albedo of 35 to 39 percent could reduce carbon dioxide emissions worth about $400 billion.
   BULLET::::- Columnist Art Ryon mentioned in his September 7, 1955, column in "The Los Angeles Times" that on September 1 it was 110 degrees in Los Angeles, yet only 105 degrees in Hell.
  
  BULLET::::- On October 17, 1958, "The Los Angeles Times" published an article, "LA's Hotter Than Hell--Only 97 There", when Los Angeles reached 104 degrees the same day.
  
  BULLET::::- According to a UPI news report, it snowed in Hell at least once, causing many to remark, "it was a cold day in Hell".
   Investigators found out that when pressures were added to the brakes, then there would be an increase in drag force and temperature on the assembly. Examination on the brake assembly of Flight 420 revealed that at the time, the brake assembly's temperature were exposed to a temperature of more than 600 degree Celsius, which may indicated that there was a significant amount of drag force at the time of the crash.
   On tarmac roads it may look as if water, or even oil, has been spilled. These kinds of inferior mirages are often called "desert mirages" or "highway mirages". Both sand and tarmac can become very hot when exposed to the sun, easily being more than 10 °C hotter than the air one meter above, enough to create conditions suitable for the formation of the mirage.
  
  Heat haze is not related to the atmospheric phenomenon of haze.
  
  Section::::Superior mirage.
   Rigid pavements are generally constructed in three layers - a prepared subgrade, base or subbase, and a concrete slab. The concrete slab is constructed according to a designed choice of plan dimensions for the slab panels, directly influencing the intensity of thermal stresses occurring within the pavement. In addition to the slab panels, temperature reinforcements must be designed to control cracking behavior in the slab. Joint spacing is determined by the slab panel dimensions.
   BULLET::::- Episode 5: Teams were affected by light snowfall in the early morning and freezing temperatures through the first part of the day. Team Solstice's low ground clearance added to difficulties in the snow. Team VW's vehicle lacked a heater, which left both teammates very cold and caused ice to build up on their windshield. Team Dart's repair job from the previous day's rollover left many spaces through which freezing air entered the passenger compartment.
   Asphalt concrete pavement mixes are typically composed of 5% asphalt cement and 95% aggregates (stone, sand, and gravel). Due to its highly viscous nature, asphalt cement must be heated so it can be mixed with the aggregates at the asphalt mixing facility. The temperature required varies depending upon characteristics of the asphalt and the aggregates, but warm-mix asphalt technologies allow producers to reduce the temperature required.
   BULLET::::- formula_18 = Form factor between the element and the sky [-]
  
  BULLET::::- formula_18 = 1 for an unshaded horizontal roof
  
  BULLET::::- formula_18 = 0,5 for an unshaded vertical wall
  
  BULLET::::- formula_21 = external radiative heat transfer coefficient [W/m²K]
  
  By expanding the above equation through substituting formula_22 the following heat loss equation is derived:
  
  formula_23
   Consider the parabola . Since all parabolas are similar, this simple case represents all others. The right-hand side of the diagram shows part of this parabola.
  
  Section::::Proof of the reflective property.:Construction and definitions.
   The weight of an asphalt pavement depends upon the aggregate type, the asphalt, and the air void content. An average example in the United States is about 112 pounds per square yard, per inch of pavement thickness.
   At the time, it was believed that the temperature at night is lowest at the ground and increases with altitude. These were based on meteorological observations that started taking temperature measurements of the atmosphere starting at a height (called the "screen height") of 1.2m from the ground.
  
  Ramdas however, conducted such measurements at a number of points closer to the ground. Observations conducted at Pune, Agra, Madras and Bhadrachalam all indicated that on clear windless nights, the minimum temperature is not on the ground but is lifted by a distance between 20 and 50 cm.
   Upon its release, "Asphalt 7" received generally favorable reviews. The iOS version holds an aggregate score of 83 out of 100 on Metacritic, based on seventeen reviews, and a score of 81% on GameRankings, based on seven reviews.
   The Court agreed with the reasoning of the district court and the court of appeals dissent that combining the claimed elements of the patent was obvious: "A separate heater can also be used in conjunction with a standard paving machine to eliminate the cold joint, and in fact is so used for heating the transverse joints of the pavement."
   The phenomenon was first reported in a 1932 paper by Ramdas and S. Atmanathan in the journal Beiträge zur Geophysik. Initially, these observations were doubted but they have been replicated widely in subsequent decades by others. The phenomenon has been named the Ramdas Layer, and is attributed to the interaction of thermal radiation effects on atmospheric aerosols and convection transfer close to the ground.
   In early June, the Indian Meteorological Department issued a severe heat wave warning in Rajasthan and nearby areas such as Delhi. The Ministry of Health advised avoiding the sun between noon and 3 p.m. and not drinking alcohol, tea, or coffee. Meanwhile the NDMA recommended covering the head, cross-ventilating rooms, and sleeping under a slightly wet sheet.
  
  Asphalt used for roads expectantly begins to melt at ; therefore, on 3 June, the government of Churu poured water onto roads in order to cool them and prevent them from melting.
   Ground cover must be evaluated for temperature differentials (i.e., anomalies such as high grass or surface debris), as to how it may affect the surface condition of the test area. Of the three methods of energy transfer, radiation is the method that has the most profound effect upon the ability of the surface to transfer energy. The ability of a material to radiate energy is measured by the emissivity of the material. This is defined as the ability of the material to release energy as compared to a perfect blackbody radiator. This is strictly a surface property. It normally exhibits itself in higher values for rough surfaces and lower values for smooth surfaces. For example, rough concrete may have an emissivity of 0.95 while a shiny piece of tinfoil may have an emissivity of only 0.05. In practical terms, this means that when looking at large areas of ground cover, the engineer in charge of testing must be aware of differing surface textures caused by such things as broom roughed spots, tire rubber tracks, oil spots, loose sand and dirt on the surface and the height of grassy areas.
   During braking, the friction surfaces (brake pads and rims) will experience thermal heating. In normal use this is not a problem, as the brakes are applied with limited force and for a short time, so the heat quickly dissipates to the surrounding air. However, on a heavily laden bike on a long descent, heat energy may be added more quickly than it can dissipate causing heat build-up, which may damage components and cause brake failure.
   Section::::See also.
  
  BULLET::::- Asphalt plant
  
  BULLET::::- Asphaltene
  
  BULLET::::- Bioasphalt
  
  BULLET::::- Bitumen-based fuel
  
  BULLET::::- Bituminous coal
  
  BULLET::::- Bituminous rocks
  
  BULLET::::- Blacktop
  
  BULLET::::- Cariphalte
  
  BULLET::::- Cooper Research Technology
  
  BULLET::::- Duxit
  
  BULLET::::- International Grooving & Grinding Association
  
  BULLET::::- Macadam
  
  BULLET::::- Oil sands
  
  BULLET::::- Pitch drop experiment
  
  BULLET::::- Pitch (resin)
  
  BULLET::::- Road surface
  
  BULLET::::- Tar
  
  BULLET::::- Tarmac
  
  BULLET::::- Sealcoat
  
  BULLET::::- Stamped asphalt
  
  Section::::Sources.
  
  BULLET::::- Barth, Edwin J., "Asphalt: Science and Technology" Gordon and Breach (1962). .
  
  Section::::External links.
  
  BULLET::::- Pavement Interactive – Asphalt
  
  BULLET::::- "Asphalt Magazine"
  
  BULLET::::- CSU Sacramento, The World Famous Asphalt Museum!
   BULLET::::- The characters "Flo" and "Sally" are based on Fran Houser of the Midpoint Café and Dawn Welch of the Rock Café respectively.
  
  BULLET::::- The bridge that McQueen sees Sally driving on resembles several bridges on Route 66, including the Cyrus Avery Route 66 Memorial Bridge in Tulsa, the Colorado Street Bridge in Pasadena, California, and the now-closed bridge over Diablo Canyon at Two Guns, Arizona.
  
  BULLET::::- The character Tex Dinoco isn't a Route 66 resident, but was inspired by the Cadillacs horns at The Big Texan Steak Ranch.
   Temperatures during the previous two days of the incident had remained in the mid-20s Fahrenheit (around -3.5 °C) and light snow was on the ground, but by mid-day on February 24 the temperature had risen to the mid-50s Fahrenheit (around 12.5 °C) and the sun was showing through clear skies.
  
raw_presuppositions: Pavement should be same temperature as the air. Pavement gets heated by the air and actual temperature.
raw_corrections: Pavement absorbs more energy from the infrared light so it is hotter.  Pavement absorbs infrared energy from sunlight in addition to getting heated from the air.