What is the shape of the meridians and parallels on the globe?

The zero parallel is the Equator line, which completely surrounds the Earth in its middle.

The parallels are similar in shape, only smaller.

Thus, their shape resembles a circle, the radius of which decreases from the Equator to the Poles.

The meridians have the shape of a semicircle, since they divide the Earth into the Western and Eastern parts with the middle at the Greenwich meridian.

In other words, we can say that the meridians are depicted in the form of an arc on the globe, and the points of their origin connect the Poles.