A creepy cloud formation was reportedly photographed today hovering over England and users on the social news Web site Reddit began spreading the picture.  

User chriswalkerb, from Yorkshire, England, posted the photograph and asked other Redditors: Creepy cloud hovering over england can anyone explain? In return, he receieved 712 comments and counting. However, no one had an exact answer. 

As an air mass blows across a mountain range at perpendicular angle to the range, it creates a standing wave, much like a river running over an underwater rock have standing waves. As the air rises, the temperature decreases and the moisture saturates the air to create the standing lenticular cloud. It gets it shape as a cigar, because air descends rapidly on the other side when it loses temperature again (loss of thermal energy in the formation of droplets). So it re-enforces the strength of the wave, making it exponentially stronger rather than weaker (like in a river). Thus you can often see lenticular clouds in formation, up to tens of miles downwind of the mountain range, replied one verbose user.

Where abouts in the UK are you living? Apart from the rain we've had the last week or two, and the odd shower, the south east has been pretty much dry since september [sic]? asked another. 

Other users simply began citing the computer game, The Sims. 

Although this cloud might look fake, the BBC has in the past documented other strange lenticular clouds over Yorkshire. Click here to see. 

On Dec. 21, a series of tsunami-shaped clouds hovered over Birmingham, Alabama. The clouds rolled like waves from west to east during the morning hours.

DVICE explained the phenomenon as such: Experts have now explained the phenomenon as perfect examples of Kelvin-Helmholtz waves, when a fast layer moves over a slower layer and drags the top along creating a curled shape. You'll recognize Kelvin-Helmholtz waves when put in context of the ocean. This kind of turbulence forms when the top layer - air - moves faster than the water layer below. This creates what we all know as wave crests or breaks when the water surges forward.

Though the cloud posted by chriswalkerb is quite unusual, it is certainly not the first strange sky formation. Environmental Graffiti has 30 photos of the Creepiest Clouds on Earth.  

So what was the creepy cloud formation glooming over England? The mystery continues.