Return of the Pogonip

Following a random, unplanned day of sunshine on Tuesday, yesterday we woke to this.

Trees and grass ‘painted’ as if by Jack Frost himself.  

A product of overnight fog and freezing temperatures this rime ice is sometimes referred-to as radiation fog, valley fog or freezing fog.  It is also called pogonip – a Shoshone word for cloud.    

Ordinarily, fog materializes when there is cooler air coming in contact-with a warmer body of water or moist surface like a swamp or wetland. 

Freezing fog materializes when the air temperature is below freezing and the water droplets in the fog become super-cooled. These super-cooled water droplets stay in liquid state until they drift into contact with a surface they can freeze-to. Grass, twigs, trees, leaves and so-forth. 

 

 

It’s really a rather striking effect and pleasing to the eye. It is also something to be reckoned-with as it can result in ice build-up on roads – especially bridges – which have no ground insulation. It can also build-up on power lines with the result pf power outages. 

Drive carefully on mornings like this.

There will most surely be ice on the roads too.....