winter tires story

[Phil Payne]

> About halfway home, on a straightaway about 3 miles long, I noticed the
> snow was gone, and the road looked wet. This was different. I turned the
> wheel a little, and NOTHING happened. It was black ice, newly frozen and
> totally invisible. And I was going about 50 miles an hour. I barely
touched
> the brakes and they locked up, so I let off instantly. I was running with
> the ABS disabled. The car was still going straight, and nothing that I did
> affected anything. This was really scary. I had no control at all.

Here in North Germany we have a very similar effect with 'Eisregen'.

It freezes - minus 6 to 10 Celcius - for a few days.  Dry.

Then an inversion layer comes over from the sea - cold upper atmosphere,
warm middle layer, clod ground layer.

Then it snows.  The snow melts as it passes through the warm layer and then
refreezes when it hits the ground.

The effects are weird.  It fills all the cracks around a car, encasing it in
polished ice.  You can get the key in the door, but the door is frozen shut.

On the roads, you get instant black ice.  Then - because ice is a good
insulator - the falling supercooled water stops freezing.  The surface that
results is so slippery you can't stand up on it.

--
  Phil Payne
  http://www.isham-research.com
  +44 7785 302 803
  +49 173 6242039