Our planet is conventionally divided into four hemispheres. How are the boundaries between them defined? What features do the hemispheres of the Earth have?
Equator and meridian
Planet Earth has the shape of a ball slightly flattened at the poles - a spheroid. In scientific circles, its shape is usually called the geoid, that is, "like the Earth." The surface of the geoid is perpendicular to the direction of gravity at any point.
For convenience, the characteristics of the planet use conditional, or imaginary, lines. One of them is the axis. It runs through the center of the Earth, connecting the top and bottom, called the North and South Poles.
Between the poles, at an equal distance from them, there is the next imaginary line, which is called the equator. It is horizontal and is a separator into the Southern (everything below the line) and Northern (everything above the line) hemispheres of the Earth. The equator is just over 40,000 kilometers long.
Another conditional line is the Greenwich, or zero, meridian. This is a vertical line through the Greenwich Observatory. The meridian divides the planet into the Western and Eastern hemispheres, and is also the starting point for measuring geographic longitude.
DifferenceSouthern and Northern Hemispheres
The equator line horizontally divides the planet in half, while crossing several continents. Africa, Eurasia and South America are partially located in two hemispheres at once. The rest of the continents are located within one. Thus, Australia and Antarctica are completely in the southern part, and North America is in the northern part.
The hemispheres of the Earth have other differences. Thanks to the Arctic Ocean at the pole, the climate of the Northern Hemisphere is generally milder than the Southern, where the land is located - Antarctica. The seasons are opposite in the hemispheres: winter in the northern part of the planet comes simultaneously with summer in the south.
The difference is observed in the movement of air and water. To the north of the equator, river flows and sea currents deviate to the right (river banks are usually steeper to the right), anticyclones rotate clockwise, and cyclones counterclockwise. South of the equator, everything is exactly the opposite.
Even the starry sky above is different. The pattern in each hemisphere is different. The main landmark for the northern part of the Earth is the North Star, in the Southern Hemisphere the Southern Cross serves as a landmark. Above the equator, land prevails, and therefore the main number of people live here. Below the equator, the total number of inhabitants is 10%, since the oceanic part predominates.
Western and Eastern hemispheres
To the east of the zero meridian is the Eastern Hemisphere of the Earth. Within its limits is Australia, most of Africa, Eurasia, part of Antarctica. Approximately 82% of the world's population lives here. In the geopolitical and cultural sense, it is called the Old World, as opposed to the New World of the American continents. In the eastern part is the largest peninsula, the deepest trough and the highest mountain on our planet.
The western hemisphere of the Earth is located west of the Greenwich meridian. It covers North and South America, part of Africa and Eurasia. It includes the entire Atlantic Ocean and most of the Pacific. Here is the longest mountain range in the world, the largest volcano, the driest desert, the highest mountain lake and a full-flowing river. Only 18% of the population lives in the western part of the world.
Dateline
As already mentioned, the Western and Eastern hemispheres of the Earth are separated by the Greenwich meridian. Its continuation is the 180th meridian, which outlines the border on the other side. It is the date line, this is where today turns into tomorrow.
Different calendar days are fixed on both sides of the meridian. This is due to the peculiarities of the rotation of the planet. The international date line mostly passes through the ocean, but also crosses some islands (Vanua Levu, Taviuni, etc.). In these places, for convenience, the line is shifted along the land border, otherwise the inhabitants of one island would exist on different dates.
