question: Why do windshield wipers leave water streaks in the middle when swiping up, but leaves no streaks wiping back down?
comment: That could happen as a result of the angle the blade. Try putting some sand on a surface and using a broom to sweep it both with a pushing motion and a pulling motion. Pulling will probably be more effective. If you're getting a lot of streaks, you might consider replacement.
passages: A "wiperless windshield" is a windshield that uses a mechanism other than wipers to remove snow and rain from the windshield. The concept car Acura TL features a wiperless windshield using a series of jet nozzles in the cowl to blow pressurized air onto the windshield. Also several glass manufacturers have experimented with nano type coatings designed to repel external contaminants with varying degrees of success but to date none of these have made it to commercial applications.
  
  Section::::Repair of stone-chip and crack damage.
   BULLET::::- In higher rainfall areas, the increased camber required to drain water, and open drainage ditches at the sides of the road, often cause vehicles with a high centre of gravity, such as trucks and off-road vehicles, to overturn if they do not keep close to the crown of the road
  
  BULLET::::- Excess dust permeates door-opening rubber moulding breaking the seal
  
  BULLET::::- Lost binder in the form of road dust, when mixed with rain, will wear away the painted surfaces of vehicles
   To minimize production costs for export, the windshield wipers used a pattern where the wipers started in the center and wiped towards the edge of the windshield, instead of from the passenger side towards the driver.
   BULLET::::- Windshield Wipers, Interval: Through Special Order, F-Series pickup buyers can take advantage of the convenience of interval windshield wipers without having to order the complete Convenience Group. By Allowing the driver to select an interval from approximately one to 12 seconds for intermittent sweeps of the wipers, interval wipers can be the ideal feature for driving in a light rain or road spray.
   BULLET::::- United States Patent 3,351,836, Robert W. Kearns, Filing date: Dec 1, 1964, Issue date: Nov 1967, "Windshield Wiper System with Intermittent Operation"
  
  BULLET::::- United States Patent 3,602,790, Robert W. Kearns, Filing date: October 18, 1967, Issue date: August 31, 1971. "Intermittent Windshield Wiper System".
  
  BULLET::::- United States Patent 4,544,870, Robert W. Kearns, Timothy B. Kearns, Filing date: Sep 7, 1982, Issue date: Oct 1, 1985, "Intermittent windshield wiper control system with improved motor speed"
  
  BULLET::::- United States Patent 3,582,747 Robert W Kearns Filing Date May 3, 1968, Issue date: June 1, 1971, "Intermittent windshield wiper system with electrodynamic braking"
   Section::::History.:Foundation, early years.
   Most wipers are of the pivot (or radial) type: they are attached to a single arm, which in turn is attached to the motor. These are commonly found on many cars, trucks, trains, boats, airplanes, etc.
   Section::::Parallel fail-over links.
   The effect that windshield wipers have on a vehicles airflow varies between vehicles; however, they are often omitted from race vehicles and high efficiency concepts in order to maintain the smallest possible coefficient of drag. A much more common option is to replace the windshield wipers with lower profile wipers, or to only remove the windshield wiper on the passenger side of the vehicle, and even to fabricate a deflector to deflect the air up and over the wipers.
   Section::::General Qualification and Licensure.
   Later in 1980, Park Avenue released the "Alien Boy" EP, consisting of the title track and three demo outtakes.
   A minimum of one operational windshield wiper, and also a windshield defogging/demisting system (or anti-fog films) that can keep the windshield clear during wet sessions must be installed on all cars, and used when necessary. The wiper blade(s) and arm(s) may be removed for dry sessions.
  
  Section::::Current Series Format.:Event Protocol.:- Multiple Class Race / Grid.
   Some vehicles are now available with driver-programmable "intelligent" (automatic) windscreen wipers that detect the presence and amount of rain using a rain sensor. The sensor automatically adjusts the speed and frequency of the blades according to the amount of rain detected. These controls usually have a manual override.
  
  Rain-sensing windscreen wipers appeared on various models in the late 20th century, one of the first being the Citroen SM. , rain-sensing wipers are optional or standard on all Cadillacs and most Volkswagens, and are available on many other mainstream manufacturers.
   Section::::Union Affiliation and Organization.
   Micro pitting
  
  Micro pitting is a fatigue failure of the surface of a material commonly seen in rolling bearings and gears.
  
  It is also known as grey staining, micro spalling or frosting.
  
  Section::::Pitting and micropitting.
  
  The difference between pitting corrosion and micropitting is the size of the pits after surface fatigue. Pits formed by micropitting are approximately 10-20 μm in depth, and micropitted metal often has a frosted or gray appearance. Normal pitting creates larger and more visible pits. Micropits are originated from the local contact of asperities produced by improper lubrication.
  
  Section::::Causes.
   Davidson (who had previously recorded with the Sage-produced Rancid Vat in 1985) played bass on the Jesus And Mary Chain's 1993 EP "Sound of Speed".
  
  Section::::Influence and legacy.
   In 1917, the Tri-Continental Corporation was founded by John R. Oishei and introduced one of the first windshield wipers, known as Rain Rubber, for the slotted, two-piece windshields found on many of the automobiles of the time.
   Early wipers were often driven by a vacuum motor powered by manifold vacuum. This had the drawback that manifold vacuum varies depending on throttle position, and is almost non-existent under wide-open throttle, when the wipers would slow down or even stop. That problem was overcome somewhat by using a combined fuel/vacuum booster pump.
  
  Some cars, mostly from the 1960s and 1970s, had hydraulically-driven wipers, most notably the '61-'69 Lincoln Continental.
   Some larger cars are equipped with hidden wipers (or depressed-park wipers). When wipers are switched off in standard non-hidden designs, a "parking" mechanism or circuit moves the wipers to the lower extreme of the wiped area near the bottom of the windscreen, but still in sight. For designs that hide the wipers, the windscreen extends below the rear edge of the hood, and the wipers park themselves below the wiping range at the bottom of the windscreen, but out of sight.
  
  Section::::Other features.:Rain-sensing wipers.
   Windshield washer fluid
  
  Windshield washer fluid (also called windshield wiper fluid, wiper fluid, screen wash (in the UK), or washer fluid) is a fluid for motor vehicles that is used in cleaning the windshield with the windshield wiper while the vehicle is being driven.
  
  Section::::Delivery system.
   The rain-sensing wipers system currently employed by most car manufacturers today was originally invented and patented in 1978 by Australian, Raymond J. Noack, see U.S. Patents 4,355,271 and 5,796,106. The original system automatically operated the wipers, lights and windscreen washers.
  
  Section::::Bladeless alternatives.
  
  A common alternative design used on ships, called a clear view screen, avoids the use of rubber wiper blades. A round portion of the windscreen has two layers, the outer one of which is spun at high speed to shed water.
   Section::::Process characteristics.:Heat transfer characteristic.
   BULLET::::- Routine ‘backwashing’, is used to achieve this. Depending on the specific application of the membrane, backwashing is carried out in short durations (typically 3 to 180 s) and in moderately frequent intervals (5 min to several hours). Turbulent flow conditions with Reynolds numbers greater than 2100, ideally between 3000 - 5000 should be used. This should not however be confused with ‘backflushing’, a more rigorous and thorough cleaning technique, commonly practiced in cases of particulate and colloidal fouling.
   BULLET::::- At values of 2000  Re  4000, there is a "critical zone" of flow, a transition from laminar to turbulence, where the value of "f" increases from its laminar value of 64 / Re to its smooth pipe value. In this regime, the fluid flow is found to be unstable, with vortices appearing and disappearing within the flow over time.
   Another instance when the diffusion-like term will be nearly zero is in the case of sharp wetting fronts, where the denominator of the diffusion-like term formula_42, causing the term to vanish. Notably, sharp wetting fronts are notoriously difficult to resolve and accurately solve with traditional numerical Richards' equation solvers.
  
  Finally, in the case of dry soils, formula_6 tends towards formula_44, making the soil water diffusivity formula_8 tend towards zero as well. In this case, the diffusion-like term would produce no flux.
  
raw_presuppositions: Windshield wipers leave streaks when swiping up but not down.
raw_corrections: Windshield wipers that are angled incorrectly can leave streaks when swiping up but not down.