No meridian is a great circle. Each meridian is a semi-circle, extending between the poles.
Lines of longitude.
They're not. A "great circle" is a circle drawn on a sphere that has its center at the center of the sphere. -- The only line of latitude that's a great circle is the equator. None of the others are. -- Each meridian of longitude is 1/2 of a great circle. In order to form a complete great circle, you have to glue it together with the other meridian of longitude that's directly opposite it on the other side of the globe. Like the Prime Meridian and 180° longitude, or 34° east longitude and 146° west longitude.
The international date line is near New Zealand. It can also be described as 180 degrees East/West. It circles the globe with the Prime Meridian.
There's no particular set or system of lines that circle the globe north and south.However, the imaginary semi-circular lines that join the north and south polesare the meridians of longitude. Each of them spans half of the globe.
This imaginary circle is called the prime meridian. it is an imaginary line that circles the globe vertically and is typically measured as beginning in Greenwich, England.
There are many things which completely circle the globe. The first thing that comes to mind is the equator, but the artic and Antarctic circles also circle the globe (as well as every other degree of latitude). The taiga forest circles the globe. The atmosphere circles the globe.
Yes, there are great circles on Earth that are entirely in water, such as the Equator or the Prime Meridian. These circles divide the Earth into two equal halves and are significant in navigation and geographical reference.
The opposite side of the globe from the Prime Meridian is called the International Date Line. It is located 180 degrees away from the Prime Meridian and serves as the marker where each new day begins.
The Prime Meridian and the meridian of 180° longitude combine to forma great circle on the Earth. Each of them alone is a semi-circle.Every parallel of latitude also circles the Earth completely, but among those,only the equator is a great circle.
Meridian.
The Prime Meridian
The equator and all lines of longitude are called great circles because the represent the circumference of the earth. The other latitude lines along the globe are smaller then the actually circumference.