Australia Weather News

There was no pot of gold at its end, but the appearance of a rare optical phenomenon allowed amateur photographer Marie Johnson to capture an image she will always treasure.

The Cobar resident could not believe her luck when she spotted a white, fuzzy bow stretching across her western New South Wales property last week.

"I've never seen one. Never, ever seen one in my life," Ms Johnson said.

"This is just sitting right on our farm; it was amazing.

"I've wanted to get some photos of the fog in the background with the old house and … when I turned around, I went, 'Oh my God, look at that.'"

At first she thought she had snapped a "big white rainbow".

"That's why I took the photos and put them up [on social media]," she said.

"Then a few other people came on and travellers, [and I learned] it's called a fogbow.

"I just thought, 'Oh wow, that's amazing.'"

Ms Johnson said the fogbow faded away after about half an hour.

Rainbow's elusive cousin

Bureau of Meteorology senior meteorologist Jonathan Howe said fogbows were made up of fog droplets, which could be 1,000 times smaller than the rain droplets that generated rainbows.

He said fogbows were uncommon in Australia.

"We often see pictures of fog growth from Canada, Europe, northern Asia and that's because of their position relative to the equator," Mr Howe said.

Mr Howe said fogbows were unusual in warmer, drier areas such as western NSW.

"Quite critically, it needs to be fog because mist droplets are quite large," he said.

"Fog in western NSW is probably not as common as the eastern parts of the state. So to see this at Cobar is quite impressive.

"They are more likely in southern parts of the country and particularly in winter, and that's because the sun is a little bit lower on the horizon."

Even more unusual are lunar fogbows, which occur at night.

"They are incredibly rare," Mr Howe said.

"The moon needs to be at a very certain angle, and there needs to be … no clouds in the sky."