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The Tropic of Cancer is one of the imaginary lines that are drawn on the surface of the Earth. It is located in the northern hemisphere and delimits the north of the intertropical zone; its southern limit is the Tropic of Capricorn. The Tropic of Cancer also joins the northernmost points where the sun reaches its zenith at the June solstice.
the parallels
Like the equator, the Tropic of Capricorn, and the Arctic and Antarctic circles, the Tropic of Cancer is a parallel. Parallels are lines formed by the intersection of the Earth’s surface with an imaginary plane perpendicular to the Earth’s axis of rotation (see the following figure).
The parallels define the latitude of the geographic coordinates and is the angle between any point of the parallel and the point of the equatorial line (the parallel with the greatest circumference, which passes through the center of the Earth, as shown in the figure) located on it. meridian (line formed by the intersection of the Earth’s surface with an imaginary plane that contains the Earth’s axis of rotation), angle with vertex at the center of the Earth. The terrestrial parallel that defines the Tropic of Cancer has a latitude of 23º 26′ 14″ north of the equator (see the following figure).
How is the Tropic of Cancer drawn?
The Tropic of Cancer is defined as the northernmost point at which the Sun reaches its zenith on the boreal summer solstice (between June 20 and 21). At that time, the sun’s rays fall vertically on the points on the earth’s surface that form the Tropic of Cancer.
The upper figure shows that the sun’s rays fall vertically on the Tropic of Capricorn, a situation that occurs in the southern summer (between December 20 and 21). Both tropics delimit the intertropical zone of the terrestrial surface. The Tropic of Cancer passes through Mexico, through the Sahara desert, China, Saudi Arabia, Egypt and India.
Etymology of the Tropic of Cancer
The origin of the name of the Tropic of Cancer goes back to antiquity; when it received its name 20 centuries ago, the boreal summer solstice occurred while the sun was in the constellation Cancer. Currently, the sun is in the constellation of Taurus at the boreal summer solstice. The term tropic comes from the Greek tropos , whose meaning is to go back; At the solstice, the sun appears to reverse the direction in which it travels the path it describes in the sky.
Importance of the Tropic of Cancer
The delimitation of the intertropical zone of the Earth by the Tropic of Cancer and the Tropic of Capricorn has several implications, particularly related to the amount of solar radiation that the Earth receives in this zone, insolation, and its incidence in the seasons and in the activities that take place.
The maximum insolation occurs when the sun’s rays fall vertically on the earth’s surface. This situation only occurs in the intertropical zone, moving throughout the year between both tropics as the Earth moves around the sun and due to the inclination of the Earth’s axis of rotation with respect to the vertical position to the translation plane. .
It is in the boreal summer solstice when the earth’s surface receives the greatest solar energy in the area where the Tropic of Cancer is drawn, between June 20 and 21. This date is associated with summer both in that area and in the regions to the north.
Sources
- Hector Israel Ramirez Torres, Flor Araceli Ruiz Peña, Monica Chaparro Esquivel, (2015). General Geography: An interactive approach for high school graduates . Editorial Group Patria, Mexico, 2015.
- Vicent J. Martínez, David Galadí-Enríquez, Joan Antoni Miralles. Fundamental Astronomy . University of Valencia, Spain, 2005.
