Looking at the globe or world map, we see a grid of thin blue lines. Among them will be the main parallels of the Earth: the equator, two polar circles, as well as the Northern and Southern tropics. We will tell you more about them in our article.
The main parallels of the Earth
All meridians and parallels on the model of our planet, of course, are conditional and imaginary. All of them were mapped for scientific and practical purposes. However, among them there are five very important parallels: the equator, the Arctic circles, the Southern and Northern tropics. The existence of all these fictional lines is directly related to real natural laws (physical and geometric). And knowledge of them is extremely important for a comprehensive study of geographical science.
The equator divides our planet into two equal halves - the Northern and Southern Hemispheres. The location of this line is strictly perpendicular to the axis of Earth's rotation. This is the longest parallel of our planet: its length is 40 thousand kilometers. In addition, the Sun at the equator twice a year is at its zenith, and the entire equatorial region of the Earth receives the largest amount of solar radiation per year.
Arctic circles are parallels that limit phenomena such as the polar day and the polar night on the surface of the planet. These lines correspond to a latitude of 66.5 degrees. In summer, residents living beyond the Arctic Circle have the opportunity to contemplate the polar days (when the Sun does not set at all over the horizon). At the same time, on the other side of the earth, the celestial luminary did not appear at all (polar night). The duration of the polar days and nights depends on how close a particular place is to the poles of the planet.
North tropic
There are two tropics on our planet, and they were not carried out by chance. Once a year the Sun is at its zenith above one of them (June 22), and after another six months - above the other (December 22). In general, the word "tropic" comes from the Greek tropikos, which translates as "turn". Obviously, we are talking about the movement of the sun in the celestial sphere.
The northern tropic is located north of the equator line. It is also called the tropic of Cancer. Where did this name come from? The fact is that two millennia ago the Sun during the summer solstice was in the constellation Cancer (now the heavenly body in this period of the year is in the constellation Gemini).
The exact latitude of the North Tropic - 23 ° 26 ′ 16 ″. However, its position changes over time due to changes in the inclination of the earth's axis, nutation, and some other geophysical processes.
Geography of the North Tropic
The northern tropic crosses three oceans (Pacific, Atlantic, Indian) and three continents (Eurasia, Africa and North America). The parallel runs through the territories of twenty states, including Mexico, Algeria, India and China.
On the latitude of the tropic of Cancer, a number of cities are located. The largest of them:
- Dhaka (Bangladesh);
- Karachi (Pakistan);
- Bhopal (India);
- Guangzhou (China);
- Medina (Saudi Arabia).
In addition, the tropic of Cancer crosses several large rivers: the Nile, Ganges, Mekong, and others. A little south of this parallel is Mecca - the main sacred place of all Muslims in the world.
South tropic and its geography
23 ° 26 ′ 21 ″ - such is the latitude of the South Tropic as of the beginning of this century. The position of this line is also unstable in time. The tropic is very slowly shifting towards the earth's equator.
The parallel also has its second name - the tropic of Capricorn. It crosses only 10 states that are located on three continents of the planet (South America, Africa and Australia). The largest city located on the tropic is Brazilian Sao Paulo. It is curious that this parallel crosses Australia almost in the middle, thereby causing a significant aridity of the climate of this continent.
The tropic of Capricorn is customary to celebrate on the ground in various ways. The most impressive sign announcing the passage of the South Tropic is in Chile. Near the city of Antofagasta in 2000, a huge 13-meter monument was built.
Finally
Now you know where the North Tropic is located, which countries and continents it crosses. It is also called the tropic of Cancer. It marks the northern latitude, above which the Sun can rise at the zenith. The tropic of Capricorn is mirrored to it in the southern hemisphere.