Why Does Steamy Window-Pans Appear Opaque? Experts Explain

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Discussion Overview

The discussion centers around the phenomenon of steam on window panes and why this condensation appears opaque rather than transparent. Participants explore the underlying mechanisms of light interaction with the water film, including aspects of refraction, droplet formation, and light scattering.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions why the thin film of condensed water is not transparent, suggesting that the film structure may become corrugated or that other mechanisms might prevent transparency.
  • Another participant proposes that distortion through refraction could be a contributing factor to the observed opacity.
  • A different viewpoint mentions that air bubbles within the water layer typically lead to translucency, impacting the clarity of the film.
  • It is noted that the condensation forms many droplets of varying thicknesses, with each droplet acting as a microlens that refracts light in different directions, leading to scattering.
  • One participant highlights that the visibility of condensation is due to light scattering and reflections occurring at the boundaries between air and water droplets.
  • A follow-up question is raised regarding the average size of the droplets and the reasons they do not coalesce into a smooth water plane, suggesting potential energy as a factor.

Areas of Agreement / Disagreement

Participants express multiple competing views on the mechanisms behind the opacity of the steam on window panes, and the discussion remains unresolved regarding the specific contributions of each proposed factor.

Contextual Notes

Participants do not reach a consensus on the exact reasons for the observed opacity, and various assumptions regarding droplet behavior and light interaction remain unverified.

zhana
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Hi,
When I boil some water,and outside is cold,window-pans in my kitchen get steamy.Here comes my question.Shouldn't that thin film of water condensate be light transparent?I wonder why becouse it is nothing else but clear water.
Does the film structure become corrugated somehow or other mechanism preventing transparency is involved?
Experts please explain -Zhana.
 
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no physicist here, but distortion thru refraction seems to be culprit.
 
How clean are your windows? In any case, there are going to be air bubbles throughout the layer- that's what usually makes a film of water translucent.
 
Also, the water condenses in many droplets of differing thicknesses. Each droplet acts like a different microlens. The light that passes through each droplet gets refracted in a different direction, scattering the light.

Njorl
 
Although the water is not visible, and the air is not visible, the border between the two is visible. A familiar example is sunlight reflecting off the surface of the water.

The visibility of condensation, mist and clouds are all results of light scattering through or reflections on the surface of minature droplets of water.
 
Thank You All for your replies,
Njorl's explanation looks promising to me to describe the structure.The film isn't smooth but the window-pan is cowered by many of small water droplets of different sizes attached to the glass surface?
If that is so ,what is the average size of such droplet and why they don't join together and form smooth water plane ?Potential energy?
 

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