My best guess would be that although condensation would transitorily occur
at all levels, the warmer air at ceiling level would be evaporating the
condensate faster than it could deposit.

Ross

"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 thought maybe it's because with a upstairs window, the top of the pane
is by the eaves, 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