A puzzling optical illusion has been glimpsed off the north Norfolk coast.

Sheringham-based artist Joanna Padfield was one of several people left fascinated this week by the sight of an ocean-going ship hovering in mid-air above the horizon out to sea.

She said she knew there would be some kind of scientific explanation for the sight, but it was nonetheless a strange thing to see.

Eastern Daily Press: Sheringham-based artist Joanna Padfield observed the fata morgana.Sheringham-based artist Joanna Padfield observed the fata morgana. (Image: Joanna Padfield)

She said: "I took this photo around midday on Tuesday (June 8) whilst on a walk along Sheringham seafront, finding inspiration for my next linocut print as I’m focusing on boats around Norfolk.

"I thought the boat looked as though it was hovering above the water but thought it was an optical illusion of some kind."

The ship is believed to be the Esvagt Njord, which services the offshore windfarms run by Equinor, Sheringham Shoal and Dudgeon.

The illusion is called a 'fata morgana' - the Italian name for Morgan the Fairy - a sorceress in medieval legends and the tales of King Arthur. She was said to have powers including changing her shape and creating mirages over water.

The effect is a kind of 'superior mirage' and occurs only when there is a strong thermal inversion - a warm layer of air sitting on top of a cooler layer.

But an inversion alone is not enough to cause a fata morgana. The mirage can only occur when something called a atmospheric duct is formed, which causes rays of light to bend as they pass through it.

Eastern Daily Press: A 'fata morgana' optical illusion was observed off the north Norfolk coast.A 'fata morgana' optical illusion was observed off the north Norfolk coast. (Image: Joanna Padfield)

Fata Morgana is most commonly seen in polar regions in colder weather but can also be observed in deserts, and on hot days.

A sighting of the phenomenon earlier this year off Cornwall made national headlines.

BBC meteorologist David Braine said at the time: "Since cold air is denser than warm air, it bends light towards the eyes of someone standing on the ground or on the coast, changing how a distant object appears."

The mirage is one possible explanation for the Flying Dutchman, a 'ghost ship' from folklore which can never go home and is doomed to sail the seas forever.