Hello All,

As it's Christmas, I've had plenty of time on my hands! Here's a why is
it puzzle!

Why does water vapour condense at the bottom of a window pane first, and
then climb up the window.

Surely if the window is cold, then water vapour should condense on all
the window at the same time?

I thought maybe it's because with a upstairs window, the top of the pane
is by the eves, so warmer. Though that doesn't explain about downstairs
window.

I can see that there's 3 events that could effect condensation on windows:

1) The direction the window is facing, as north facing windows are more
prone to condensation.

2) The air that circulate around a house.

3) Actual properties of the glass is such that when it's in a vertical
position, it's colder at the bottom than the top.

Perhaps I should start another uni project !

Joe
Wolverhampton

"Joe Egginton" wrote in message
...
Hello All,

As it's Christmas, I've had plenty of time on my hands! Here's a why
is it puzzle!

Why does water vapour condense at the bottom of a window pane first,
and then climb up the window.

Surely if the window is cold, then water vapour should condense on all
the window at the same time?

I would guess it's airflow down the cold pane as the air in contact with
the pane is cooled and sinks to be replaced by warmer air from the top
of the pane. The glass and air in contact are probably cooler at the
bottom of a pane hence more condensation, perhaps there is even some
evaporation at the top.

Tom

I have a contact in Australia. I'll ask him what happens there - could
be some clues as to whether or not this phenomenon is gravity related
or is something much more subtle to do with the earth's orientation in
space.

Joe. Maybe you could publish an interim thesis at the beginning of
April.

Jack

Yes,

But maybe that might not be altogether conclusive. Just maybe the well known
'northerly force of evaporation' can more readily overcome the weaker
gravitational downwards force towards the higher altitudes of a window even
in antipodeal locations.

Hmmm.

Ross

wrote in message
oups.com...
I have a contact in Australia. I'll ask him what happens there - could
be some clues as to whether or not this phenomenon is gravity related
or is something much more subtle to do with the earth's orientation in
space.

Joe. Maybe you could publish an interim thesis at the beginning of
April.

Jack