Why is it that the ice that forms on the windscreen is much harder to
shift than that which forms on the other windows of the car?

On Fri, 17 Oct 2008 01:46:07 -0700 (PDT), wrote:

Why is it that the ice that forms on the windscreen is much harder to
shift than that which forms on the other windows of the car?

Yeah.That's true.It is very hard isn't it .
You've not had any yet have you?

wrote in message
...
Why is it that the ice that forms on the windscreen is much harder to
shift than that which forms on the other windows of the car?

Being less vertical, there is less run off of condesing water prior to
freezing, so the windscreen ice tends to be thicker. Often, sometimes, the
windscreen is facing away from the buildings and is more exposed as well.
Well, I just made all that up but it sounds plausible!


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

In article
,
wrote:
Why is it that the ice that forms on the windscreen is much harder to
shift than that which forms on the other windows of the car?

Probably because it's cleaner so the ice gets a better hold. The traffic
film on the others only gets partially removed by washing.

Also the further from vertical the window is the more the ice seems to
form.

--
*The severity of the itch is proportional to the reach *

Dave Plowman London SW
To e-mail, change noise into sound.

On Oct 17, 9:52*am, "Bob Mannix" wrote:

Often, sometimes,

You used to be indecisive but now you're not so sure?

"mike" wrote in message
...
On Oct 17, 9:52 am, "Bob Mannix" wrote:

Often, sometimes,

-You used to be indecisive but now you're not so sure?

ooo that's a tricky one....I think so )


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

On Fri, 17 Oct 2008 01:46:07 -0700 (PDT), wrote:

Why is it that the ice that forms on the windscreen is much harder to
shift than that which forms on the other windows of the car?

Interesting question....often noticed it but never really thought
about why it should be.

I doubt it's that the glass is any colder than the rest, so I'm going
to go for the glass being cleaner, thus allowing the ice to bind more
effectively to the surface. You should notice a difference in the
amount of elbow grease it takes to shift the ice from the area outside
the sweep of the wipers compared to that within it.

Regards,



--
Steve ( out in the sticks )
Email: Take time to reply: timefrom_usenet{at}gmx.net

On Fri, 17 Oct 2008 09:52:35 +0100, "Bob Mannix"
wrote:


wrote in message
...
Why is it that the ice that forms on the windscreen is much harder to
shift than that which forms on the other windows of the car?

Being less vertical, there is less run off of condesing water prior to
freezing, so the windscreen ice tends to be thicker. Often, sometimes, the
windscreen is facing away from the buildings and is more exposed as well.
Well, I just made all that up but it sounds plausible!

Not sure that's entirely true, as I've noticed that it's as easy to
clear ice of the sunroof as it is the side windows. However, your
theory might fit in with that of mine ( the glass being cleaner )
inasmuch as condensing water isn't dispersed by dirt and thus tends to
form beads, which will undoubtedly be harder to remove than the
relatively flat layer of ice on the other glass.
The aspect makes a difference - on mornings where there's a light
frost the glass in the lee of the wind is often quite free of ice.

Regards,



--
Steve ( out in the sticks )
Email: Take time to reply: timefrom_usenet{at}gmx.net

wrote:
Why is it that the ice that forms on the windscreen is much harder to
shift than that which forms on the other windows of the car?

upward slanting surface gets colder.

On Oct 17, 9:48*am, wrote:
Yeah.That's true.It is very hard isn't it .
You've not had any yet have you?

I had to scrape the wife's car today seems too early to me, but we
had no clouds last night and live on top of a hill so wind chill may
have played a part I guess.

On Fri, 17 Oct 2008 12:24:59 +0100, The Natural Philosopher
wrote:

wrote:
Why is it that the ice that forms on the windscreen is much harder to
shift than that which forms on the other windows of the car?

upward slanting surface gets colder.

Yet it's easier to remove the ice from the rear of an estate and a
hatchback...the former having a steeper angle than the windscreen, the
latter more less so.

Regards,


--
Steve ( out in the sticks )
Email: Take time to reply: timefrom_usenet{at}gmx.net

wrote in message
...
Why is it that the ice that forms on the windscreen is much harder to
shift than that which forms on the other windows of the car?

I have a quick clear electrically heated windscreen...the days of doing all
that scraping are well and truely over

wrote in message
...
On Oct 17, 9:48 am, wrote:
Yeah.That's true.It is very hard isn't it .
You've not had any yet have you?

I had to scrape the wife's car today seems too early to me, but we
had no clouds last night and live on top of a hill so wind chill may
have played a part I guess.

You are under the thumb. Tell her to scrape her own screen.

The first ice on a windsceen = bonfire night. I can see a massive party
happening near the 5th of November at my house.

Adam

On Oct 17, 9:46*am, wrote:

Why is it that the ice on the windscreen is harder to
shift than that which forms on the other windows of the car?

Always assuming there is truth in the question, the fact that the
screen would be cleaner, better polished and in the streamline would
all tend to make the windscreen a more difficult surface to form on
rather than the easier one presumed by most of your correspondents.

However, once crystals form they will be easier to grow and harder to
remove.

I just give the screen a squirt of de-icer from a made up solution
(spray on ether based crap just wastes time and patience.) One of
those kitchen cleaner spray bottles is ideal.

Hit the bonnet too as that is a source of cold air and moisture.

It's cheap, effective and quick.

What is most annoying is that the stuff is always at its greatest cold
and thickness on the days I am late for work. The timing is excellent.

If I was going to work at 4 am, it would be nothing more than dew with
potential to annoy. If I was going off at 10 am it would be melting.

How does it know that that 6:30 to 8:00 am is the sweet spot? Barrsud!

"Weatherlawyer" wrote in message
...
On Oct 17, 9:46 am, wrote:

Proper toughened ice.

http://en.wikipedia.org/wiki/Pykrete

Adam

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "ARWadsworth"
saying something like:


"Weatherlawyer" wrote in message
...
On Oct 17, 9:46 am, wrote:

Proper toughened ice.

http://en.wikipedia.org/wiki/Pykrete

I read "Pyke, the Unknown Genius" a couple of years ago. Strange bod,
altogether.

On Oct 20, 6:10*pm, "ARWadsworth"
wrote:
"Weatherlawyer" wrote in message

...
On Oct 17, 9:46 am, wrote:

Proper toughened ice.

http://en.wikipedia.org/wiki/Pykrete

I wonder why that isn't used in Yukon where the mining camps rely on
ice roads for heavy traffic.

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Weatherlawyer
saying something like:

Proper toughened ice.

http://en.wikipedia.org/wiki/Pykrete

I wonder why that isn't used in Yukon where the mining camps rely on
ice roads for heavy traffic.

Impractical in term of cost for all but the shortest of roads.

|"Weatherlawyer" wrote in message
...
|On Oct 17, 9:46 am, wrote:
|
| Why is it that the ice on the windscreen is harder to
| shift than that which forms on the other windows of the car?
|
|Always assuming there is truth in the question, the fact that the
|screen would be cleaner, better polished and in the streamline would
|all tend to make the windscreen a more difficult surface to form on
|rather than the easier one presumed by most of your correspondents.

Have a look at the shape of your car. In particular, note the *slope* of
the pieces of glass in the windows.

Modern aerodynamic styling favours a shallow angle windscreen to ease the
airflow with a rather steeper back window. To provide the maximum space for
passengers, the side windows are almost vertical.

What has this got to do with it? On a clear night, surfaces cool below air
temperature by radiation to outer space. Vertical windows have a low
exposure to the sky and so will not cool below air temperature so much. If
your car is parked near the house (as mine is), the heat from the house may
well outbalance the radiation loss to such sky as the windows on that side
see and so they will not freeze at all.

The more sloping front and back windows will lose more heat to the sky and
so cool further below air temperature. It is this that encourages the
thicker and harder ice layer to form. Because ice is a very good radiator
at infra-red wavelengths, once that ice layer starts to form a "feedback"
sets in to magnify the effect.

It also depends on the dew point. If the dew point is below freezing, hoar
frost will form directly on the glass. If it is just above, water will form
first and then freeze. This last is much harder to remove than frost alone.
Likewise, if it has been raining and the rainwater film freezes.
--
- Yokel -
oo oo
OOO OOO
OO 0 OO
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) ( /\ ) (

"Yokel" posts via a spam-trap account which is not read.

Have a look at the shape of your car. In particular, note the *slope* of
the pieces of glass in the windows.

Modern aerodynamic styling favours a shallow angle windscreen to ease the
airflow with a rather steeper back window. To provide the maximum space for
passengers, the side windows are almost vertical.

What has this got to do with it? On a clear night, surfaces cool below air
temperature by radiation to outer space. Vertical windows have a low
exposure to the sky and so will not cool below air temperature so much. If
your car is parked near the house (as mine is), the heat from the house may
well outbalance the radiation loss to such sky as the windows on that side
see and so they will not freeze at all.

The more sloping front and back windows will lose more heat to the sky and
so cool further below air temperature. It is this that encourages the
thicker and harder ice layer to form. Because ice is a very good radiator
at infra-red wavelengths, once that ice layer starts to form a "feedback"
sets in to magnify the effect.

It also depends on the dew point. If the dew point is below freezing, hoar
frost will form directly on the glass. If it is just above, water will form
first and then freeze. This last is much harder to remove than frost alone.
Likewise, if it has been raining and the rainwater film freezes.

Sounds very odd to me if an object radiates that doesn't have to go up
to the Sky at all..

When the clouds clear the infra red is lost to space when the clouds are
there its reflected back!..

Sure this isn't anything to do with dew or water particles and the
incline of the surface?..
--
Tony Sayer