When looking at a world map, we notice the existence of some “imaginary lines” drawn in the horizontal direction. Two of them are known as Tropic of Cancer and Tropic of Capricorn, respectively. But what are these lines?
The tropics of the Earth are parallel, that is, lines drawn cartographically in the east-west direction, parallel to the equator line. As such, they have specific latitudes. In the case of the Tropic of Cancer, the latitude is 23º27' N (23 degrees and 27 minutes north), while in the Tropic of Capricorn the latitudes are 23º27' S (23 degrees and 27 minutes south).
The fact that both tropics have the same latitude, but in different hemispheres, means that both are at the same distance from the Equator line, which delimits half of the Earth, that is, the area that has an equal distance between the extreme north and the extreme south of our planet.
Thus, everything found between the tropics is called intertropical, while localities located to the north or south of the tropics are called subtropical.
But what are the tropics of Cancer and Capricorn for?
thanks to the solstices and equinoxes, the sun affects its radiation in different ways throughout the year. In some periods, it is more inclined to the north, in others, to the south, and there are also times when the two hemispheres are equally illuminated.
The tropics serve to demarcate the limit of this difference, that is, the Tropic of Cancer is the most northerly zone where the sun shines perpendicularly. Likewise, the Tropic of Capricorn is the belt in the southern hemisphere where perpendicular illumination is at its maximum.
Do not stop now... There's more after the advertising ;)
When this zone of illumination reaches one of the tropics, it is observed the position of the sun over the zenith, which is the highest point in the sky in a vertical observation.
Therefore, this is the function of the tropics, to mark the areas of the Earth that receive the maximum solar radiation during the year. Thus, it is possible to say that the intertropical bands are more illuminated by the sun than the subtropical ones, which makes them, in general, warmer.
Monument dedicated to the Tropic of Cancer in Taiwan
In addition to this function, the tropics also help in the demarcation of seasons. When the sun's vertical axis hits a tropic, the seasons change. When it occurs in the Tropic of Cancer, there is summer in the northern hemisphere and winter in the southern hemisphere, the reverse happening when the sun reaches the Tropic of Capricorn.
Sign indicating that the Tropic of Capricorn passes there, in Australia
The Tropic of Cancer “cuts” in the imaginary sense the following countries: Saudi Arabia, Algeria, Bahamas, Bangladesh, Chad, China, Egypt, UAE, United States, India, Libya, Mali, Mauritania, Mexico, Myanmar, Niger, Oman and Taiwan.
The Tropic of Capricorn passes through South Africa, Argentina, Australia, Brazil, Botswana, Chile, Mozambique, Madagascar, Namibia and Paraguay.
By Rodolfo Alves Pena
Graduated in Geography
