Beetham Tower was humming again on Friday night as the region was battered by Storm Arwen.

Many people took to social media to report a strange noise as the region was hit by gusts of up to 50mph.

@R0binHood tweeted: Can anyone else hear that low buzzing sound in hulme/deansgate area of Manchester? It may just be howling wind but it sounds like a giant white noise machine is blasting out across the city."

The source of the noise was of course Beetham Tower.

READ MORE: Storm Arwen: LIVE updates as snow and strong winds hit UK and Greater Manchester

The 47-floor tower has often made the noise over the years when the region is hit by strong wind.

Others also reported on social media that they could hear the hum.

@danmayor99 tweeted: "Hearing the Beetham Tower hum in the wind is very spooky."

@MarbleToMoon said: "You know its stormy outside when you can hear the wind whistling round Beetham Tower from inside your living room!"

@fiofo tweeted: "Beetham Tower is singing again! I haven't heard it in years, I thought they must've fixed it! Blimey, it must be blowing a gale out there"

@DemonTomatoDave said: "Ooh the Beetham Tower's singing at the top of its lungs tonight."

And @xaret added: "I can hear Beetham Tower whistling with the wind tonight, pretty cool. Sounds like a UFO. Only in Manchester".

It's down to Beetham Tower

But why does the tower make the distinctive noise when it is windy?

Professor Trevor Cox, a professor of acoustic engineering at Salford University previously told the M.E.N. that it's because of the fins at the top of the building.

It's akin to blowing across the top of a bottle and getting a sound.

He said: "When you blow across the top of a beer bottle, the air moving across the edge creates a sound. The same thing is happening with the Beetham Tower, air moving across the edge of the fins on the top of the building create sound."

An early temporary repair to the tower involved putting foam across the edge of the fins, which stopped the noise.

Professor Cox added: "The air movement then excites a resonance, probably of the air gaps between the fins, but the panels might also be flexing. The lattice work on top of building has the panels all spaced the same distance apart, and the resonance at 240Hz is caused by this periodicity."

Basically, the faster the air moves across the fins, the louder the noise. Because of the spacing, it creates a specific sound. In musical note terms, it is "about B below middle c for those who want to play along."