If you were in China last week, you could have been forgiven if you believed the end of days had arrived.

For one moment UFO-shaped clouds were floating across the blue skies - and then days later a halo appeared around the Sun, appearing to give it a halo for a few hours.

Both are simple weather phenomena - but both are also strange and unexpected sights that baffled many onlookers.

A lenticular cloud in the shape of a UFO seen in the sky above Jilin province, China: The lens-shaped clouds form at high altitude

The unusual cloud above appeared over Jilin Province, China.

It is known as a lenticular clouds, and their spectacular shapes are popular with UFO believers, who spot the resemblance to flying saucers.

The clouds generally form over mountains - although in rare instances they can be caused by shear winds, and have been spotted over the UK on occasion.

The clouds generally form when stable air flows over the top of a mountain.

The moisture droplets are pushed up a steep slope, condensing into cloud on their way, and forming in a spiral formation over the top.

For people living near mountains, these sightings are a common occurrence.

But when visitors see one - or the cloud forms away from mountains - they are a startling shape.

Straight lines rarely form in nature, so to see such a tightly packed shape is a curious event.

The clouds usually form when air passes over mountain tops - and are popular with UFO believers

A solar halo or 'sundog' is even more rare. This one appeared in the sky above Lhasa, Tibet on Sunday.

Sundogs are made commonly of plate-shaped hexagonal ice crystals in high and cold cirrus clouds.

These crystals act as prisms, bending the light rays passing through them.

The phenonemen is officially called a pathelia but is also known as a 'halo' or 'mock sun'.. The sight is more commonly seen when the sun is low in the sky and not in the middle of the day.

Cultures around the globe have traditionally given great significance and meaning to a sun dog when they see one.

A sun dog is believed to have appeared in the sky before the Battle of Mortimer's Cross, one of the most impossible battles during the War of the Roses in 1461.

The Yorkist leader, who later became Edward IV, convinced his nervous troops that the strange sight was a good omen and won a decisive victory.

Looking up: A girl takes a picture of a 'Sundog' sun halo hovering in the sky above Lhasa, Tibet

The sundog appears above houses in Lhasa, formed through the lens of ice crystals in high and cold cirrus clouds