That's like asking "How many marks are there on a ruler ?"
There are 360 degrees of longitude around the Earth. Some maps and globes
have a line every 10 degrees, some have a line every 15 degrees, some have
a line every 30 degrees, and some don't have any lines printed on them at all.
The mapping software that I use will print 1,800 lines in every degree, if I feel
that I need them for some reason. And no matter how many lines there are on
your map, there are always longitudes between the lines, just like there are
lengths between the marks on the ruler.
There is no official, standard set of 'lines' that everybody has to use. You can have
as few or as many lines on your map as you feel comfortable with.
Longitude is measured from zero 180° east, and from zero to 180° west, for a total
of 360° . You're free to draw as few or as many lines in those ranges as you like to
have on your maps.
Some commercially-printed maps and globes print a line every 30°, some a line
every 20°, or 15°, or 10°, and some don't print any lines at all. The mapping
software that I use will print a line for me every 2" if I want it, which adds up
to 648,000 lines around the Earth if I want them all printed.
There is no standard set of "lines" that everybody must use. The questrion is
exactly the same as asking: "How many lines of length are there on a ruler ?"
Latitude lines are parallel but not longitude lines.
The horizontal lines are called latitudes and the vertical lines are called longitudes.
There are 360 longitudes
The horizontal lines are called latitudes and the vertical lines are called longitudes.
longitudes or meridians
There can be infinitely many lines: think of the longitudes through he North and South poles. However, there can be only one straight line.
Many imaginary lines run through India. Latitudes and longitudes for instance.
meridians or lines of longitude
All longitudes converge at the north and south poles.
They are lines of longitude and latitude, often just longitudes and latitudes.
Longitudinal or longitude lines are the imaginary lines that are perpendicular to the equator. Latitudinal or latitude lines are parallel to the equator.
The lines joining the two poles are longitudes.