The rare natural phenomenon is known as lenticular clouds, according to Le Dinh Quyet, deputy head of the forecasting department at the Southern Center for Hydro-meteorological Forecasting.

They are dense, stationary clouds which are caused by sudden air movements and can often be found near hills or mountains. 

As moist and stable air flows over a larger eddy, like those caused by mountains, coupled with temperatures dropping below the dew point, lenticular clouds can then be formed.

Last year also saw the same rate phenomenon occur in the area. The images have gone viral on social media in recent times, drawing plenty of attention from viewers online.

Standing at 986 metres above sea level, Ba Den Mountain in Tay Ninh has been dubbed the roof of southern Vietnam. Viewed from a distance, the mountain can stand out amid the blue sky and is sometimes left hidden behind clouds and fog.

From the base to the top of the mountain, visitors are able to stop and explore temples, pagodas, and towers featuring local architecture, which is a mix of Buddhist and folklore culture, with these sites attracting millions of visitors each year.

Source: VOV