
They caused panic across Cape Town, as locals feared they were being invaded after a series of perfectly circular 'UFO' clouds gathered above.

Social media was filled with images of the strange formations.

Meteorologists call them lenticular clouds, and they form when strong, wet winds blow over rough terrain - such as the 3,500-foot (1,066-meter) Table Mountain.

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It caused panic across Cape Town, as locals feared they were being invaded after a series of perfectly circular 'UFO' clouds gathered above.

WHAT ARE LENTICULAR CLOUDS? Lenticular clouds are more or less isolated clouds, which form in the Earth's troposphere (the lowest level of the atmosphere). They are saucer- or lens-shaped clouds, which are typically stationary in nature. Lenticular clouds have been divided into three different categories, altocumulus standing lenticular, stratocumulus standing lenticular, and cirrocumulus standing lenticular, depending on the height at which they may be found above the surface of the Earth. On account of their typical shapes, lenticular clouds have been mistakenly identified as Unidentified Flying Objects (UFOs) in the past. Advertisement

The unusual meteorological sighting happened on November 8 and citizens in the South African city rushed to the streets to gaze up at the natural spectacular.

'The aliens have been moniting [sic] cape town for years now,' Instagram user monre44 said.

However, keen to dispel rumors that the formation was an out-of-this-world visit, CNN meteorologist Derek Van Dam said they are 'common clouds' known scientifically as 'stratocumulus standing lenticularis'.

They are saucer- or lens-shaped clouds, which are typically stationary in nature.

On account of their typical shapes, lenticular clouds have been mistakenly identified as Unidentified Flying Objects (UFOs) in the past.

Social media users were eager to photograph the beautiful daytime cloud formations and post their images online.

'Right now above my head! The strangest most amazing UFO shaped clouds,' wrote amazed Instagram user called Arthur Albert.

Shocked Twitter user Monique Jackson added: 'Weird UFO clouds over Cape Town.'

While impressed Di Brown posted on Instagram: 'The cloud looks like a tornado in pause mode. Really very weird skies today.

'Table Mountain showing off and looking spectacular as usual .

'Apparently these cloud formations are called #lenticular clouds. You learn something every day.'

Meteorologist Mr Van Dam wrote on Facebook: 'They form when conditions are just right.

Meteorologists call them lenticular clouds, and they form when strong, wet winds blow over rough terrain, - such as the 3,500-foot (1,066-meter) Table Mountain.

They are saucer- or lens-shaped clouds, which are typically stationary in nature. On account of their typical shapes, lenticular clouds have been mistakenly identified as Unidentified Flying Objects (UFOs) in the past.

'Air flows along the surface of the earth and reaches some sort of obstruction like a mountain or valley.'

eNCA meteorologist Annette Venter said: 'This occurs when stable, moist air flows over a mountain, creating a series of oscillating waves. If the temperature at the crest of the wave equals the dew point temperature, condensation occurs in a lens formation.'

She added: 'As the air falls down the trough of the wave, where the temperature and dew point temperature are not equal, evaporation occurs.

'Thus, a wave cloud, or a series of lenticular clouds, is capable of forming.

'These are often mistaken for UFOs because of the saucer-like shape.'

One amazed Instagram user called Arthur Albert captioned his image: 'Right now above my head! The strangest most amazing UFO shaped clouds', while many took to social media to post pictures.

While Di Brown described the formation as 'spectacular' and posted on Instagram: 'The cloud looks like a tornado in pause mode. Really very weird skies today'