question: According to my weather app, the temperature is 47 degrees, but it feels like 43 degrees. What makes one temperature "feel like" another but not become it?
comment: Wind can make it feel cooler than it really is. Humidity can make it feel warmer than it really is.
passages: Apparent temperature
  
  Apparent temperature is the temperature equivalent perceived by humans, caused by the combined effects of air temperature, relative humidity and wind speed. The measure is most commonly applied to the perceived outdoor temperature. However it also applies to indoor temperatures, especially saunas and when houses and workplaces are not sufficiently heated or cooled.
  
  BULLET::::- The heat index and humidex measure the effect of humidity on the perception of temperatures above . In humid conditions, the air feels much hotter because less perspiration evaporates from the skin.
   Section::::Influencing factors.:Relative humidity.:Interplay of temperature and humidity.
  
  Various types of apparent temperature have been developed to combine air temperature and air humidity. 
  
  For higher temperatures, there are quantitative scales, such as the heat index.
  
  For lower temperatures, a related interplay was identified only qualitatively:
  
  High humidity and low temperatures cause the air to feel chilly.
  
  Cold air with high relative humidity "feels" colder than dry air of the same temperature because high humidity in cold weather increases the conduction of heat from the body.
   The variation in temperature that occurs from the highs of the day to the cool of nights is called diurnal temperature variation. Temperature ranges can also be based on periods of a month, or a year. 
  
  The size of ground-level atmospheric temperature ranges depends on several factors, such as:
  
  BULLET::::- The average temperature
  
  BULLET::::- The average humidity
  
  BULLET::::- The regime of winds (intensity, duration, variation, temperature, etc.)
  
  BULLET::::- The proximity to large bodies of water, such as the sea
   The heat index and its counterpart the humidex both take into account only two variables, shade temperature and atmospheric moisture (humidity), thus providing only a limited estimate of thermal comfort. Wind passing over wet or sweaty skin causes evaporation and a wind chill effect that the heat index does not measure. The other major factor is sunshine; standing in direct sunlight can add up to to the apparent heat compared to shade. There have been attempts to create a universal apparent temperature, such as the wet-bulb globe temperature, "relative outdoor temperature", "feels like", or the proprietary "RealFeel".
  
  Section::::Meteorological considerations.
   ASHRAE 55-2010 defines SET as "the temperature of an imaginary environment at 50% relative humidity,  average air speed, and mean radiant temperature equal to average air temperature, in which total heat loss from the skin of an imaginary occupant with an activity level of 1.0 met and a clothing level of 0.6 clo is the same as that from a person in the actual environment, with actual clothing and activity level."""
   During winter months (Dec-Feb), high temperatures can vary between and , while night time temperatures can reach below . In the summer (Jun-Aug), temperatures peak around . The very high summer humidity (average 70%) and low cloud cover can mean that the heat index temperature is or more higher than the air temperature.
  
  BULLET::::- Climatic classification: zone D, 1416 GR/G
  
  BULLET::::- Atmospheric diffusivity: low, Ibimet CNR 2002
  
  Section::::History.
  
  Section::::History.:Ancient and medieval ages.
   For example, under the standard Köppen system, in the United States, western Washington and Oregon are classed into the same climate zone as southern California, even though the two regions have strikingly different weather and vegetation. Under the old Köppen system cool oceanic climates like that of London or Seattle were classed in the same zone as hot subtropical cities like Savannah, Georgia or Brisbane, Australia. In the United States, locations like Colorado and Kansas, which have long, severe winter climates where plants are completely dormant, were classed into the same climate zone as Louisiana or northern Florida which have mild winters and a green winter landscape.
   BULLET::::- In June 2017, more than 40 airline flights in the United States were grounded, with American Airlines reducing sales on certain flights to prevent the vehicles from being over the maximum weight permitted for safe takeoff and Las Vegas tying its record high at .
  
  BULLET::::- In June 2017 again, a heatwave in Iran broke record high temperature. On 28 June 2017, the city of Jask had a dew point of degrees, which is rare. But the highest temperature in Ahvaz soared to degrees and the humidity creates a heat index of .
   BULLET::::- "T" = air temperature, °C
  
  Section::::Alternative approaches.:North American and United Kingdom wind chill index.
   Predicted mean vote is an index that predicts the mean value of the thermal sensation votes (self-reported perceptions) of a large group of persons on a sensation scale expressed from -3 to +3 corresponding to the categories "cold," "cool," "slightly cool," "neutral," "slight warm," "warm," and "hot."
  
  Section::::Definitions.:Comfort zone.
  
  Comfort zone refers to the combinations of air temperature, mean radiant temperature (tr), and humidity that are predicted to be an acceptable thermal environment at particular values of air speed, metabolic rate, and clothing insulation (I)
  
  Section::::Definitions.:Clothing insulation (I).
   Many formulas exist for wind chill because, unlike temperature, wind chill has no universally agreed upon standard definition or measurement. All the formulas attempt to qualitatively predict the effect of wind on the temperature humans "perceive". Weather services in different countries use standards unique to their country or region; for example, the U.S. and Canadian weather services use a model accepted by the National Weather Service. That model has evolved over time.
   Temperature (/TA) is the air temperature in whole degrees Celsius as a two-digit value, with negative temperatures preceded by a minus (-) sign. In the United States, negative temperatures are preceded by the letter M (M).
  
  Wind velocity (/WV) must contain both the wind speed and direction. Direction is reported as a three-digit value in whole degrees true and the wind speed in knots also in three digits.
   BULLET::::- polar-continental air masses, cold and dry in winter, hot and dry in summer; arisen from east and northeast;
  
  BULLET::::- arctic-maritime air masses pervade from North Atlantic Ocean, within the pale of polar circulation. Determine frosty weather and relatively wet in winter, and in spring and autumn frosts;
  
  BULLET::::- tropical-maritime air masses, that pervade from the south and southwest, determine during the winter mists and heavy snow falls, and in summer determine atmospheric instability;
   Even though Priorat DOQ covers a small area, there are several different micro-climates present. Generally, the climate is more extreme than most continental climate areas, though there is a marked contrast between the valleys and the higher areas. There are both freezing winds from the north (mitigated somewhat by the Montsant mountain) and also the warm Mistral wind from the east.
   Hello I Feel the Same is the ninth studio album by American alternative band The Innocence Mission. It was released on October 16, 2015, via Korda Records, a cooperative record label founded by The Ocean Blue, a band with whom the Innocence Mission formed a "long and deep friendship that goes back to some of each band's first shows in Pennsylvania and their major label debut records on Sire and A&M". An edition on translucent green vinyl was released from early January 2016. It is their first studio album since 2010's "My Room in the Trees", making five years the longest gap between studio albums in their career.
   United States temperature extremes
  
  For the United States, the extremes are in Death Valley, California in 1913 and recorded in Prospect Creek, Alaska in 1971.
  
  The largest recorded temperature change in one place over a 24-hour period occurred on January 15, 1972 in Loma, Montana, when the temperature rose from . 
  
  The most dramatic temperature changes occur in North American climates susceptible to Chinook winds. For example, the largest 2-minute temperature change of occurred in Spearfish, South Dakota, a rise from .
  
  Section::::Lack of extremes.
   During summer, Cabo San Lucas is cooler than San José del Cabo by about 1.5 to 3 °C (3 to 5 °F). Sometimes during the summer, when winds blow from the Pacific Ocean instead of the Gulf of California, the differences in temperatures between San José del Cabo and Cabo San Lucas are higher.
   BULLET::::- Albany, Western Australia, Australia ("Csb")
  
  Section::::Group C: Temperate/mesothermal climates.:"Csc": Mediterranean cold summer climates.
  
  Cold summer Mediterranean climates ("Csc") exist in high-elevation areas adjacent to coastal "Csb" climate areas, where the strong maritime influence prevents the average winter monthly temperature from dropping below 0 °C. This climate is rare and is predominantly found in climate fringes and isolated areas of the Cascades and Andes Mountains, as the dry-summer climate extends further poleward in the Americas than elsewhere. Rare instances of this climate can be found in some coastal locations in the North Atlantic and at high altitudes in Hawaii.
  
  Examples
   Section::::Models.:PMV/PPD method.:Local thermal discomfort.:Draft.
  
  While air movement can be pleasant and provide comfort in some circumstances, it is sometimes unwanted and causes discomfort. This unwanted air movement is called "draft" and is most prevalent when the thermal sensation of the whole body is cool. People are most likely to feel a draft on uncovered body parts such as their head, neck, shoulders, ankles, feet, and legs, but the sensation also depends on the air speed, air temperature, activity, and clothing.
  
  Section::::Models.:PMV/PPD method.:Local thermal discomfort.:Vertical air temperature difference.
   The apparent temperature (AT), invented in the late 1970s, was designed to measure thermal sensation in indoor conditions. It was extended in the early 1980s to include the effect of sun and wind. The AT index used here is based on a mathematical model of an adult, walking outdoors, in the shade (Steadman 1994). The AT is defined as; the temperature, at the reference humidity level, producing the same amount of discomfort as that experienced under the current ambient temperature and humidity.
  
  The formula is:
  
  where:
  
  BULLET::::- "T" = dry bulb temperature (°C)
  
  BULLET::::- "e" = water vapour pressure (hPa)
   The standard wind chill formula for Environment Canada is:
  
  When the temperature is and the wind speed is , the wind chill index is −24. If the temperature remains at −20 °C and the wind speed increases to , the wind chill index falls to −33.
  
  The equivalent formula in US customary units is:
  
  Windchill temperature is defined only for temperatures at or below and wind speeds above .
   BULLET::::- Almaty, Kazakhstan ("Dfa")
  
  BULLET::::- Oral, Kazakhstan ("Dfa")
  
  BULLET::::- Aomori, Aomori Prefecture, Japan ("Dfa")
  
  BULLET::::- Nagano, Nagano Prefecture, Japan ("Dfa")
  
  BULLET::::- Sapporo, Japan ("Dfa", bordering on "Dfb")
  
  BULLET::::- Chicago, Illinois, United States ("Dfa")
  
  BULLET::::- Boston, Massachusetts, United States ("Dfa")
  
  BULLET::::- Minneapolis, Minnesota, United States ("Dfa")
  
  BULLET::::- Toronto, Ontario, Canada ("Dfa", bordering on "Dfb")
  
  BULLET::::- Hamilton, Ontario, Canada ("Dfa", bordering on "Dfb")
  
  BULLET::::- Windsor, Ontario, Canada ("Dfa")
  
  BULLET::::- Bucharest, Romania ("Dfa")
  
  BULLET::::- Rostov-on-Don, Russia ("Dfa")
  
  BULLET::::- Volgograd, Russia ("Dfa")
  
  New York City is on the borderline between this climate and the humid subtropical (Cfa) climate, the line passing through the city.
   There are two variations of a desert climate: a hot desert climate ("BWh"), and a cold desert climate ("BWk"). To delineate "hot desert climates" from "cold desert climates", there are three widely used isotherms: most commonly a mean annual temperature of , or sometimes a mean temperature of in the coldest month, so that a location with a "BW" type climate with the appropriate temperature above whichever isotherm is being used is classified as "hot arid" ("BWh"), and a location with the appropriate temperature below the given isotherm is classified as "cold arid" ("BWk").
   Winters are cold and the air temperature can drop to or below on average of 22 days of the year and on average of 3.7 days of the year, and are often broken up by warm, dry Chinook winds that blow into Alberta over the mountains. These winds can raise the winter temperature by , and as much as in just a few hours, and may last several days. As well, Calgary's proximity to the Rocky Mountains affects winter temperature average mean temperature with a mixture of lows and highs, and tends to result in a mild winter for a city in the Prairie Provinces. Temperatures are also affected by the wind chill factor, Calgary's average wind speed is , one of the highest in Canadian cities.
   Section::::Reliability.:Sayings which may be locally accurate.:Calm conditions.
  