Yesterday in Ireland, on one of the warmest days of the year so far, Dubliners were treated to a natural wonder.

Spotted In Dublin! http://t.co/4XqZyPuE8a pic.twitter.com/a4b0tmeKjx

— 98FM (@98FM) June 30, 2015

The skies above Dublin city filled with altocumulus lenticularis – clouds that bear a striking resemblance to flying saucers.

UFO Clouds are Awesome @LovinDublin @lecooldublin @DublinTown @DublinDiaries @dublin pic.twitter.com/N3xpjjdm7P

— Cathy Burke (@CloudBurke) June 30, 2015

Lenticular clouds normally form perpendicular to the direction of the wind, in conditions where stable, moist air collides with mountains or large man-made structures.

RT @LiveNaasWeather The day #Dublin came under siege of UFOS! Altocumulus Lenticularis Clouds! pic.twitter.com/XFDkcCFZDL

— Adrian Linares (@Adriansweather) June 30, 2015

Satellite imaging offered a birds-eye view of the clouds above Dublin yesterday.

High resolution visible satellite imagery of Dublin lenticular clouds from today. http://t.co/5gEfFlw1sr pic.twitter.com/UMAbty6WsE

— Tim Ballisty (@IrishEagle) June 30, 2015

The unique shapes the cloud formation takes on are thought to be one of the most common explanations for apparent UFO sightings.

Spectacular shot of todays #Lenticular #Clouds over Ballyfermot #Dublin 10 by Amanda Devlin. #Ireland pic.twitter.com/NQix5oraA3

— Kildare Weather (@LiveNaasWeather) June 30, 2015

Have you ever seen lenticular clouds in person? Let us know in the comment section, below.

Related: Dublin, Weather