Frostflowers: Fractal, Feathered or Fern-like?

This is the time of year for Jack Frost and his ice patterns!

The swirls in the photo above graced the roof of my car some days ago and made me wonder how they came to form in the way that they do.

I am, alas, no scientist, but it seems that small environmental changes, for example in air temperature, air movement, in the number of water molecules or in the quantity of dust particles, cause an ice pattern to grow, perhaps by developing long frond-like arms, thereby deviating from its original flower-like design.

But what causes these formations in the first place? Well, in the case of windows, it seems that frost patterns emerge when a pane of glass is exposed to sub-zero temperatures on the outside and moist air on the inside. Water vapour in the atmosphere condenses and becomes frost on the internal surface of the glass. These days with central heating, we rarely see frost patterns inside our homes, but I recall the high sash windows of my teenage years and the chilly patterns that delighted us on winter mornings.  

• The Story of Snow: what we sometimes miss
• Fern pattern
• Frost photos

Natural Phenomena ~ Perseid Meteor Showers in Suffolk

OK, so these aren't *real* stars ... (Ipswich Waterfront by Night)

A mini meteor shower of Tweets announced that folk were outside gazing at shooting stars last night here in the Ipswich area. We went outside, and it was only seconds before David spotted something star-like zooming across the sky. At that point the only moving items I could see were aeroplanes: their flashing lights proved something of a distraction. I came in for a while, but we both ventured out again later and this time we both met with success.

The BBC announced that we are approaching the 'high point of the annual Perseid meteors' as we orbit through debris from comet 'Swift-Tuttle'.

Suffolk, of course, was not the only place from which to watch the spectacle. You can read about the phenomenon in Galloway here.