Vertical lines parallel to the prime meridian are lines of longitude.
They are lines of longitude or meridians.
The only lines that can run parallel to the Prime Meridian on any map are other meridians of longitude, and the only map on which they can be printed parallel to it is a Mercator Projection. They are not really parallel to the Prime Meridian.
There are no geographic lines that are parallel to the Prime Meridian. Technically, every meridian of longitude is parallel to every other meridian of longitude, but only over an infinitesimal distance north or south of the equator. I'm quite sure that's not what you're looking for.
The lines are parallel on the map are called Latitudes.
No lines are parallel to the Prime Meridian. All of the meridians of longitude are farthest apart at the equator, and all converge at the north and south poles. Parallel lines would be the same distance apart everywhere, and never meet.
Lines of longitude.
There are no geographic lines that are parallel to the Prime Meridian. Technically, every meridian of longitude is parallel to every other meridian of longitude, but only over an infinitesimal distance north or south of the equator. I'm quite sure that's not what you're looking for.
Lines of longitude.
No. Longitudinal lines run parallel to the Prime Meridian. Latitudinal lines run parallel to the Equator.
They go straight up and down in parallel. (This is as opposed to a Robinson Projection where they bow out and away from the Prime Meridian.)
vertical
The Prime Meridian (of 0 degrees west or east) run north-south through Greenwich in London, UK. Lines that run north-south that are parallel to the Prime Meridian (but which meet at the poles) and which describe the distance west or east of this line are called lines of Longitude.Lines of Latitude describe the distance north or south of the equator.
The Prime Meridian is a Longitudinal line. That is, it runs North and South between the poles. Latitudinal lines run parallel to the equator and measure distance North or South of the equator. They run East and West, perpendicular to longitudinal lines. The Prime Meridian is at all latitudes.