question: Why do sunlight reflections, particularly those off of cars, seem to flicker?
comment: I'm pretty sure it's due to the air getting hot and therefore moving up. The movement makes the light flicker. Pretty normal sight in summer. Difficult to tell from what you described. The tubes probably do not heat the air up the way the cars do.
passages: Flicker can also be perceived from naturally modulated light sources like candle light or a sunlit water surface or it may be experienced while driving along a row of trees lit by the sun. TLMs and resulting flicker can be seen also while driving with a certain speed along a street or through a tunnel lit by lighting equipment positioned with a regular spacing.
  
  Section::::Visibility.
  
  Temporal light modulations become visible if the modulation frequency is below the flicker fusion threshold and if the magnitude of the TLM exceeds a certain levels.
   As an example, when a picture is taken indoors, the brightness of outdoor objects seen through a window may be 70 or 80 times brighter than objects inside the room. If exposure levels are set for objects inside the room, the bright image of the windows will bleed past the window frames when convolved with the Airy disc of the camera being used to produce the image.
  
  Section::::Practical implementation.
   Temperature variations in the air can also cause refraction of light. This can be seen as a heat haze when hot and cold air is mixed e.g. over a fire, in engine exhaust, or when opening a window on a cold day. This makes objects viewed through the mixed air appear to shimmer or move around randomly as the hot and cold air moves. This effect is also visible from normal variations in air temperature during a sunny day when using high magnification telephoto lenses and is often limiting the image quality in these cases.
   Such internal scattering is also present in the human eye, and manifests in an unwanted veiling glare most obvious when viewing very bright lights or highly reflective surfaces. In some situations, eyelashes can also create flare-like irregularities, although these are technically diffraction artifacts.
   Stray light is a major issue in the design of a coronagraph, used for observing the Sun's corona.
  
  Section::::Sources.
  
  There are many sources of stray light. For example:
  
  BULLET::::- "Ghost orders" in diffraction gratings. These can be caused by periodic variations in the spacing of grooves in ruled gratings, for instance.
  
  BULLET::::- Light scattered towards a telescope from particles along the optical path to a star.
  
  BULLET::::- Light emitted by components of the optical system.
  
  BULLET::::- Infrared optical systems are, obviously, especially susceptible due to thermal radiation.
   The meteorologist Sakuhei Fujiwhara wrote "Atmospheric Light Phenomena" in 1933, but in it, he wrote that he did not know the cause of shiranui, and due to some who profited from delighting sightseers, he pointed out the possibility that they are from noctiluca.
   BULLET::::- The inner-ear condition Ménière's disease can be aggravated by flicker. Sufferers of vertigo are recommended to not use fluorescent lights.
  
  BULLET::::- Polymorphous light eruption is a condition affecting the skin thought to be caused by an adverse reaction to ultraviolet light. Its prevalence across Europe is 10-20% of the population. Artificial light sources may provoke the condition, and compact fluorescent light have been shown to produce an eruption.
   BULLET::::1. Reflection of star lights
  
  BULLET::::2. Luminous jellyfish
  
  BULLET::::3. Fire from undersea active volcano
  
  BULLET::::4. Light of fishing boats
   BULLET::::- Auroral light (northern and southern lights, aurora borealis and aurora australis)
  
  BULLET::::- Belt of Venus
  
  BULLET::::- Brocken Spectre
  
  BULLET::::- Circumhorizontal arc
  
  BULLET::::- Circumzenithal arc
  
  BULLET::::- Cloud iridescence
  
  BULLET::::- Crepuscular rays
  
  BULLET::::- Earth's shadow
  
  BULLET::::- Earthquake lights
  
  BULLET::::- Glories
  
  BULLET::::- Green flash
  
  BULLET::::- Halos, of Sun or Moon, including sun dogs
  
  BULLET::::- Heiligenschein or halo effect, partly caused by the opposition effect
  
  BULLET::::- Light pillar
  
  BULLET::::- Mirages (including Fata Morgana)
  
  BULLET::::- Rainbows
  
  BULLET::::- Shadow set
  
  BULLET::::- Sun dogs
  
  BULLET::::- Tyndall effect
  
  Section::::A list of optical phenomena.:Other optical phenomena.
  
  BULLET::::- Dichromatism
  
  BULLET::::- Gegenschein
  
  BULLET::::- Iridescence
  
  BULLET::::- Opposition effect
  
  BULLET::::- Sylvanshine
   One form of flare is specific to digital cameras. With the sun shining on an unprotected lens, a group of small rainbows appears. This artifact is formed by internal diffraction on the image sensor, which acts like a diffraction grating. Unlike true lens flare, this artifact is not visible in the eyepiece of a digital SLR camera, making it more difficult to avoid.
  
  Section::::See also.
  
  BULLET::::- Bokeh, a source of circles around out-of-focus bright points, also due in part to the internals of the lens.
  
  BULLET::::- Diffraction spike, a type of lens flare seen in some telescopes
   Section::::Experimental considerations.
   There are several atmospheric conditions which may cause the effect, most commonly a type of halo, caused by the 
   Section::::Experimental setup.
   BULLET::::- Other colours in the sky, such as glowing skies at dusk and dawn. These are from additional particulate matter in the sky that scatter different colors at different angles.
  
  BULLET::::- Halos, afterglows, coronas, and sun dogs. These are from scattering, or refraction, by ice crystals and from other particles in the atmosphere. They depend on different particle sizes and geometries.
   Flare is the diffraction of light in the human lens, resulting in "rays" of light emanating from small light sources, and can also result in some chromatic effects. It is most visible on point light sources because of their small visual angle.
   There are much more factors that determine the visibility of TLMs as flicker:
  
  BULLET::::- The shape properties of the light waveform (e.g. sinusoidal, rectangular pulse and its duty cycle); see Figure 1;
  
  BULLET::::- The average light level of the light source and its contrast with the background light level within the environment;
  
  BULLET::::- The viewing angle and changes in direction of view by the observer;
  
  BULLET::::- Physiological factors such as age and fatigue.
   Section::::Motion.
  
  A reporting of motion of the LF was common among astronauts who experienced the flashes. For example, Jerry Linenger reported that during a solar storm, they were directional and that they interfered with sleep since closing his eyes would not help. Linenger tried shielding himself behind the station's lead-filled batteries, but this was only partly effective.
   Section::::Modern lights.
   Section::::Colorimetric purity.
   Light trails is another photographic effect where motion blur is used. Photographs of the lines of light visible in long exposure photos of roads at night are one example of effect. This is caused by the cars moving along the road during the exposure. The same principle is used to create star trail photographs.
   Further background and explanations on the different TLA phenomena are given in a recorded webinar “"Is it all just flicker?"”. Models for the visibility of flicker and stroboscopic effect from the temporal behavior of luminous output of LEDs are in the doctoral thesis of Perz.
  
  Section::::Root causes.
  
  The root cause of TLAs is the variation of the light intensity of lighting equipment. Important factors that can contribute and that determine the magnitude and type of light modulation of lighting equipment are:
   Some phenomena are yet to be conclusively explained and may possibly be some form of optical phenomena. Some consider many of these "mysteries" to simply be local tourist attractions that are not worthy of thorough investigation.
  
  BULLET::::- Hessdalen lights
  
  BULLET::::- Min Min lights
  
  BULLET::::- Light of Saratoga
  
  BULLET::::- Naga fireballs
  
  Section::::Further reading.
  
  BULLET::::- Thomas D. Rossing and Christopher J. Chiaverina, Light Science: Physics and the Visual Arts, Springer, New York, 1999, hardback,
  
  BULLET::::- Robert Greenler, Rainbows, Halos, and Glories, Elton-Wolf Publishing, 1999, hardback,
   Shortly after sunset and before sunrise, artificial satellites often look like stars—similar in brightness and size—but move relatively quickly. Those that fly in low Earth orbit cross the sky in a couple of minutes. Some satellites, including space debris, appear to blink or have a periodic fluctuation in brightness because they are rotating. Satellite flares can appear brighter than Venus, with notable examples including the International Space Station (ISS) and Iridium Satellites.
   Referring to the Marfa Lights View Park east of Marfa, James Bunnell states, "you might just see mysterious orbs of light suddenly appear above desert foliage. These balls of light may remain stationary as they pulse on and off with intensity varying from dim to almost blinding brilliance. Then again, these ghostly lights may dart across the desert...or perform splits and mergers. Light colors are usually yellow-orange but other hues, including green, blue and red are also seen. Marfa Mystery Lights (MLs) usually fly above desert vegetation but below background mesas."
  
  Section::::History.
   Veiling glare
  
  Veiling glare is an imperfection of performance in optical instruments (such as cameras and telescopes) arising from incoming light that strays from the normal image-forming paths, and reaches the focal plane. The effect superimposes a form of noise onto the normal image sensed by the detector (film, digital sensor, or eye viewing through an eyepiece), resulting in a final image degraded by loss of contrast and reduced definition.
  
  Section::::Scenes.
  