It was not an alien invasion portal, but strange shapes were appearing in the skies over large parts of Queensland on Tuesday.

Clouds looking like shattered ice cubes appear in the sky over Brisbane. ( Facebook: Melissa Thomas )

Social media was abuzz with pictures of incredible cloud formations as Mother Nature turned on a great show.

Fluffy cotton-ball clouds or cirrocumulus clouds filled the sky for most of the day and were punctuated at one point by a strange portal-like hole over Brisbane.

It sent social media into meltdown with speculation about what it was and even seasoned weather watchers were excited by what they saw.

Harry Clark from the Bureau of Meteorology said the hole in the sky was a fall-streak hole, also called a punch hole cloud.

"They're not common, we do see them from time to time," he said.

"They are pretty spectacular and quite unusual, so it is exciting to see them over the sky at the moment.

"Ice crystals start to form and fall down out of the cloud and as they do so they cannibalise the cloud, so you're left with this little hole.

"It is a pretty spectacular phenomenon and was very visible along the east coast [on Tuesday]."

A stunning cloud formation visible at Bridgeman Downs in northern Brisbane on Tuesday morning. ( Facebook: Aly Webster )

But Mother Nature apparently cannot take all of the credit.

"It is really quite complicated how the initial hole forms, but what you generally need is something to stir up the cloud and start the process of turning the super-cooled liquid water in clouds into ice and for it to start falling out to create the hole," Mr Clark said.

"A plane flying through the cloud is one way of doing that, or even just general waves in the atmosphere might be enough to kick it off."

He said the clouds were so impressive even forecasters were keen to admire them.

"There are some very enthusiastic people in the office when it comes to clouds, so it was nice to be able to sit back and look at some of the more beautiful parts of nature," he said.