Triangle UFOs are being reported across the globe, but mainly in the USA.

Each time they are reportedly black in colour, of an enormous size, relatively low flying, at slow speeds and utterly silent.

Reports on underside lights can vary with one type having a light at each corner and a larger middle one.

The other type reported tends to have five or seven lights in a V shape along two of the sides.

Many witnesses report feeling a sense of fear or awe at the siting and sometimes numbness and memory loss.

The latest sighting reported to the Mutual UFO Network, a US database of UFO reports from across the globe, happened in Glasgow, in Scotland.

The witness, who has not been named by MUFON, said it happened at 9.40pm yesterday as he parked in his drive.

He said: "My attention was taken by something that appeared to be visibly moving through the darkness of the night sky about 50 to 100 feet above me. 

"Noticeable to me, due to three dim, but visible glowing orange rings that outlined a triangular shaped object. 

"I would say that the object I was viewing from my perspective, was passing over me showing its undercarriage. 

"The object was not illuminated by any other lights , only by the orange rings as I indicated earlier. 

"The object appeared to be dark in colour as it was being viewed by myself from the ground and was a dark night sky above. 

"This said, the outline of the object was visible enough to the naked eye and unmistakably triangular."

He estimated it was moving at only 20 to 30 mph.

He added: "It moved silently, with no air movement felt, travelling west, to an easterly direction the object passed out of my sight over the neighbouring property. 

"I did run to the main road which was some 20 metres from my viewing position in the drive... to try and capture an image. 

"However a combination of the time to set the camera on my phone, and trying to pinpoint object in a now brightly lit street, ended the encounter with only my account as documented here."

The witness was also left in awe.

He added: "I feel personally as though I have encountered something remarkable."

He said he reported it to police in the area.

A year ago Express.co.uk revealed the number of triangle UFO sightings received by MUFON were on the increase.

In some cases they are reportedly as big as a football pitch.

The most infamous mass triangle UFO sighting was the Phoenix Lights incident of March 13 1997 over Arizona.

Five lights were seen in a formation by thousands of people over three hours from 7.30pm to 10.30pm.

The sightings took place a cross a 300-mile area from Phoenix to Tucson.

It was blamed by officials as military flares at the time.

Some witnesses later reported memory loss experiences.

Another mysterious case was the Belgian UFO wave from November 1989. 

Thirty different groups of witnesses, and three groups of police officers, reported seeing on November 29 a large object flying at low altitude. 

The craft was described as "flat, of triangular shape, with lights underneath", and being silent as it slowly moved across Belgium towards the Netherlands and Germany.

Some alien hunters believe they are the motherships of aliens visiting Earth.

However, many conspiracy theorists believe they are actually secret aircraft developed by the US Air Force (USAF) and other military which are being tested or used.

The TR-3B is alleged by conspiracy theorists to be a secret "black project" spy craft of the US Government that can be flown into space.

It is described as having lights at each corner and one in the centre.

The allegations are that these crafts are created at top-secret military bases like Area 51 in Nevada, by reverse engineering alien technology.

Although MUFON investigates the bizarre triangle sightings, it still urges caution.

Roger Marsh, MUFON director of communications, said: “Please remember that most UFO sightings can be explained as something natural or man-made.”

Scott Brando runs website ufoofinterest.org which exposes hoax UFO sightings.

He is sceptical any unexplainable sightings have been made.

He says the Phoenix Lights Incident was explained as aircraft and military flares.

He told Express.co.uk: “The Phoenix lights were explained with two different events. The first was the flight of five planes in V-shape formation.

"This is what the witness saw in that day.

"The second event was the launch of military flares over Estrella mountains."

He said of the Belgian UFO Wave: "The Belgian UFO wave began as a normal sighting (some lights in the sky) and then spread virally, but it took more time because at that time the 

media coverage had no internet like now."

Referring to triangle UFOs generally, he added: “About other similar sightings I'd like to see some reports by MUFON, however many formation of sky lanterns or the launch of skydivers

Golden Knights were often mistaken for UFOs.”