[jamest (OP)]

Michelle writes in and attaches this picture: 'Below is a photo that I too at 02:15 in the morning of 12 June 2024. The photo hasn?t been cropped or changed in any way.

Unfortunately it doesn?t show the cloud as I saw it;  it looked like a tube.

It was an otherwise clear night and quiet cold as we were in the beginning of winter.

The cloud stretched quite a way back behind my house and into the distance in front.

What kind of cloud is this and what causes it?'

[alancalverd]

Conceivably a vapor trail from a single-engine ducted-fan aircraft https://www.flugzeuginfo.net/images/gallery/2013/ea-7optica_aeroelvira_g-bopo_10_oldwarden2013.jpg, or (more likely)  a roll cloud,  on the leading edge of a sea breeze front or (more rarely) downwind of a long straight ridge
https://greencomet.org/wp-content/uploads/2014/02/roll-cloud-Daniela-Mirner-Eberl-290x290.jpg