These images show how sand falling on Spain after travelling across the Mediterranean Sea from the Sahara Desert is so intense that it has turned the sky orange.

This weather phenomenon, known as a calima, was observed in the municipality of Mojacar, in the southern Spanish province of Almeria, from 14th March. Many other areas of Spain are also reportedly affected by the sand.

The calima is a naturally occurring phenomenon in the region, but this year’s event is said to have been one of the strongest ones ever witnessed, with sand from the Sahara Desert being lifted up into the air in a vortex before travelling sometimes hundreds of miles and being dumped elsewhere. It usually takes place in the Canary Islands, which are part of Spain.

In the images, the sky appears to have been turned orange against the backdrop of the dark streets in the town below.

This calima has been described as one of the most intense ever and Spanish citizens have been advised by the authorities to protect themselves by closing their windows, avoiding going out and if they must, wearing a face mask, since the poor air quality and the dust can adversely affect their health.