Cloud-watchers near Coffs Harbour were treated to a spectacular fallstreak hole or hole-punch cloud yesterday. These have been discussed here before.

They can form in clouds that contain supercooled water droplets at a temperature below freezing point, but not frozen. A trigger such as a passing aircraft causes ice crystals to form and a chain reaction called the Wegener-Bergeron-Findeisen process makes water droplets around those crystals evaporate – leaving a ‘hole’ around the wispy patch of ice crystals.

Refraction of sunlight by the ice crystals results in the rainbow, while the arrangement of those crystals gives us a bright patch of light in the middle called a sun dog.

I saw a remnant of the Coffs Harbour one or another with a sun dog from my place about 50 Km north of Coffs at 10.30 am.

“More”: http://news.nationalgeographic.com/news/2014/11/141104-hole-punch-cloud-rainbow-atmosphere/

Lucky duck. I’ve never seen one.

:)

Here’s a spectacular one.. I thought that there was some shopping going on at first

Ian said:

Here’s a spectacular one.. I thought that there was some shopping going on at first

Looks like it’s been made by some sort of flying machine.

Michael V said:

Lucky duck. I’ve never seen one.

:)

It was only about a fifth of the width of the one in the first image but very nice.

:)

Ian said:

Cloud-watchers near Coffs Harbour were treated to a spectacular fallstreak hole or hole-punch cloud yesterday. These have been discussed here before.

They can form in clouds that contain supercooled water droplets at a temperature below freezing point, but not frozen. A trigger such as a passing aircraft causes ice crystals to form and a chain reaction called the Wegener-Bergeron-Findeisen process makes water droplets around those crystals evaporate – leaving a ‘hole’ around the wispy patch of ice crystals.

Refraction of sunlight by the ice crystals results in the rainbow, while the arrangement of those crystals gives us a bright patch of light in the middle called a sun dog.

I saw a remnant of the Coffs Harbour one or another with a sun dog from my place about 50 Km north of Coffs at 10.30 am.

“More”: http://news.nationalgeographic.com/news/2014/11/141104-hole-punch-cloud-rainbow-atmosphere/

SuperDooperMagnificent.