question: ELIF: why is the air coming in cold when you open a moving car window, despite it being warm outside?
comment: Imagine that you're covered head to toe in hair and the air that's flowing past you is really strong sticky tape. The more tape flows past you, the more body hair it's ripping off you. The air removes heat from you as it flows past you, cooling you down and making it feel cold.
passages: The importance of the infrared atmospheric window in the atmospheric energy balance was discovered by George Simpson in 1928, based on G. Hettner's 1918 laboratory studies of the gap in the absorption spectrum of water vapor. In those days, computers were not available, and Simpson notes that he used approximations; he writes: "There is no hope of getting an exact solution; but by making suitable simplifying assumptions . . . ." Nowadays, accurate line-by-line computations are possible, and careful studies of the infrared atmospheric window have been published.
  
  Section::::Kinetics of the infrared atmospheric window.
   BULLET::::- In a warm occlusion, the cold air mass overtaking the warm front is warmer than the cool air ahead of the warm front, and rides over the colder air mass while lifting the warm air.
   In warm climates the window is used for exhausting ventilation air. Cooler air enters the cavity at the bottom, from the interior space, is heated during transfer upwards through the cavity and is exhausted at the top of the cavity to the exterior. In cold climates the window is used for intake of ventilation air. Cold air enters the bottom of the cavity, from the outside, is heated during transfer upwards though the cavity, and enters the interior space at the top of the cavity. More complex designs exist, which for example do not transfer ventilated air between the interior and exterior, or which have multiple ventilation channels.
   The fall of the Soviet Union led to massive restructuring and deindustrialization of many of the former Soviet Bloc. When the Kyoto Protocol was negotiated, there were several mechanisms that allowed for trading of emissions credits. These included credits produced under the Joint Initiative (JI) provision: Emission Reduction Unit credits; the Clean Development Mechanism (CDM): Certified Emission Reduction credits; and Assigned Amount Units (AAU) now also widely known as Hot Air in the post Soviet context. These were given to Russia as an incentive to sign the treaty. Critical climate change experts decry these credits as a way for countries to buy their way out of taking action to address climate change. 
   BULLET::::- Influence of window surface temperature on comfort
  
  There are two reasons why people feel discomfort when they are close to a cold window surface. First, a cold window is the reason for outflow of heat, which is produced by the cutaneous covering of the individual. Second, a cold window provokes the circulation of air, which is felt like a draft. 
   Hot air (economics)
  
  Hot air in economics refers to the Assigned Amount Units (AAU) credits given for the reduction of Green House Gas (GHG) emissions among the former Soviet Bloc countries since 1990. 
   BULLET::::- Thermal transmittance (U-factor), best values are around U-0.15 (equal to 0.8 W/m2/K)
  
  BULLET::::- Solar heat gain coefficient (SHGC), ratio of solar heat (infrared) passing through the glass to incident solar heat
  
  BULLET::::- Visible transmittance (VT), ratio of transmitted visible light divided by incident visible light
  
  BULLET::::- Air leakage (AL), measured in cubic foot per minute per linear foot of crack between sash and frame
  
  BULLET::::- Condensation resistance (CR), measured between 1 and 100 (the higher the number, the higher the resistance of the formation of condensation)
   Adam and Jamie tackle not so much a myth as what they call an "urban puzzle". The debate arises because both methods of cooling influence a car's fuel efficiency—air conditioning requires a lot of power to run, but at the same time, open windows create drag. This myth was revisited in "MythBusters Revisited".
  
  Section::::Episode 23 – "Exploding House".
  
  BULLET::::- Original air date: November 16, 2004
  
  Section::::Episode 23 – "Exploding House".:Needle in a Haystack.
   A newer version from Nibe Sweden the F730 takes in additional air from outdoors to the above process - this is a more powerful type of EAHP with an inverter controlled compressor. Out put from the heat pump can vary from 1.1 to 6 kW and the discharged air from this unit can be as low as -15 °C
  
  Section::::NIBE.
  
  F200P 
  
  BULLET::::- Discontinued
  
  F360P 
  
  BULLET::::- Discontinued
  
  F205 F370 F470
  
  F750
  
  F730
  
  Section::::Issues.
   BULLET::::- Open system: Outside air is drawn from a filtered air intake (Minimum Efficiency Reporting Value MERV 8+ air filter is recommended). The cooling tubes are typically long straight tubes into the home. An open system combined with energy recovery ventilation can be nearly as efficient (80-95%) as a closed loop, and ensures that entering fresh air is filtered and tempered.
   Section::::Lineup history.:2007.
  
  BULLET::::- 16 – 18 August 2007
   A "reverse" Rijke effect — namely, that a Rijke tube will also produce audio oscillations if "hot" air flows through a "cold" screen — was first observed by Rijke's assistant Johannes Bosscha and subsequently investigated by German physicist Peter Theophil Rieß.
  
  Section::::Mechanism.
   Since buildings are not totally sealed (at the very minimum, there is always a ground level entrance), the stack effect will cause air infiltration. During the heating season, the warmer indoor air rises up through the building and escapes at the top either through open windows, ventilation openings, or unintentional holes in ceilings, like ceiling fans and recessed lights. The rising warm air reduces the pressure in the base of the building, drawing cold air in through either open doors, windows, or other openings and leakage. During the cooling season, the stack effect is reversed, but is typically weaker due to lower temperature differences.
   Section::::Applications.
  
  Section::::Applications.:Rotary thermal wheel.
   Throughout the cooling season, the system works to cool and dehumidify the incoming, outside air. This is accomplished by the system taking the rejected heat and sending it into the exhaust airstream. Subsequently, this air cools the condenser coil at a lower temperature than if the rejected heat had not entered the exhaust airstream. During the heating seasons, the system works in reverse. Instead of discharging the heat into the exhaust airstream, the system draws heat from the exhaust airstream in order to pre-heat the incoming air. At this stage, the air passes through a primary unit and then into a space. With this type of system, it is normal, during the cooling seasons, for the exhaust air to be cooler than the ventilation air and, during the heating seasons, warmer than the ventilation air. It is for this reason the system works very efficiently and effectively. The coefficient of performance (COP) will increase as the conditions become more extreme (i.e., more hot and humid for cooling and colder for heating).
   In a car equipped with air conditioning, outside air, or cabin air if the recirculation flap has been set to close the external air passages, is first forced, often after being filtered by a cabin air filter, through the air conditioner's evaporator coil. This can be thought of as a heater core filled with very cold liquid that is undergoing a phase change to gas (the evaporation), a process which cools rather than heats the incoming air. In order to obtain the desired temperature incoming air may first be cooled by the air conditioning and then heated again by the heater core. In a vehicle fitted with manual controls for the heater and air conditioning compressor, using both systems together will dehumidify the air in the cabin, as the evaporator coil removes moisture from the air due to condensation. This can result in increased air comfort levels inside the vehicle. Automatic temperature control systems can take the best course of action in regulating the compressor operation, amount of reheating and blower speed depending upon the external air temperature, the internal one and the cabin air temperature value or a rapid defrost effect requested by the user.
   Section::::Lineup history.:2008.
  
  BULLET::::- 14–16 August 2008
   For primary defogging, heat is generally provided by the vehicle's engine coolant via the heater core; fresh air is blown through the heater core and then ducted to and distributed over the interior surface of the windshield by a blower. This air is in many cases first dehumidified by passing it through the vehicle's operating air conditioning evaporator. Such dehumidification makes the defogger more effective and faster, for the dried air has a greater capacity to absorb water from the glass at which it is directed.
  
  Section::::Types.:Secondary defogger.
   reaching a relatively high velocity before rising due to heat exchange with heat sources (e.g., occupants, computers, lights). Absorbing the heat from heat sources, the cold air becomes warmer and less dense. The density difference between cold air and warm air creates upward convective flows known as thermal plumes. Instead of working as a stand-alone system in interior space, displacement ventilation system can also be coupled with other cooling and heating sources, such as radiant chilled ceilings or baseboard heating.
  
  Section::::History.
   It is also recommended that the PIR not be placed in such a position that an HVAC vent would blow hot or cold air onto the surface of the plastic which covers the housing's window. Although air has very low emissivity (emits very small amounts of infrared energy), the air blowing on the plastic window cover could change the plastic's temperature enough to trigger a false alarm.
  
  Sensors are also often designed to "ignore" domestic pets, such as dogs or cats, by setting a higher sensitivity threshold, or by ensuring that the floor of the room remains out of focus.
   To cool the air it used latent heat (in other words, cooling by water evaporation). Water inside the device evaporates and in the process transfers heat from the surrounding air. The cool moisture-laden air is then directed to the inside of the car. The evaporate "cooling" effect decreases with humidity because the air is already saturated with water. Therefore, the lower the humidity, such as in dry desert regions, the better the system works. Car coolers were popular, especially among summer tourists visiting or crossing the southwestern United States states of California, Arizona, Texas, New Mexico, and Nevada.
  
  Section::::Operating principles.
   It is likely that Robert Stirling's air engine of 1818, which incorporated his innovative "Economiser" (patented in 1816) was the first air engine put to practical work. The economiser, now known as the regenerator, stored heat from the hot portion of the engine as the air passed to the cold side, and released heat to the cooled air as it returned to the hot side. This innovation improved the efficiency of Stirling's engine and should be present in any air engine that is properly called a Stirling engine.
   Section::::Categories.:Forced-air.
   The rotating wheel heat exchanger is composed of a rotating cylinder filled with an air permeable material resulting in a large surface area. The surface area is the medium for the sensible energy transfer. As the wheel rotates between the ventilation and exhaust air streams it picks up heat energy and releases it into the colder air stream. The driving force behind the exchange is the difference in temperatures between the opposing air streams which is also called the thermal gradient. Typical media used consists of polymer, aluminum, and synthetic fiber.
   Section::::Cooling.
  
  Cooling refers to the process of becoming cold, or lowering in temperature. This could be accomplished by removing heat from a system, or exposing the system to an environment with a lower temperature.
  
  Coolants are fluids used to cool objects, prevent freezing and prevent erosion in machines.
  
  Air cooling is the process of cooling an object by exposing it to air. This will only work if the air is at a lower temperature than the object, and the process can be enhanced by increasing the surface area or decreasing the mass of the object.
  
presuppositions: If the wind outside of a car is hot, and is blowing on you while you drive with the windows down, the air should feel hot, and not cold. 
corrections: The warm wind that blows into the windows blows on the driver as well, removing the heat from you, making it a cooling experience. 
raw_presuppositions: If the wind outside of a car is hot, and is blowing on you while you drive with the windows down, the air should feel hot, and not cold.  The air that blows on you as you drive with the car windows down is warm and therefore is should not cool the driver down. 
raw_corrections: The warm wind that blows into the windows blows on the driver as well, removing the heat from you, making it a cooling experience.  The warm wind that blows into the windows blows on the driver as well, removing the heat from you, making it a cooling experience. 