A new approach to mapping continental tropics based on the relationship between temperature, altitude, and latitude

Abstract

There are several approaches to defining the concepts of the intertropical region and tropical climates. The main definitions use latitude, annual average temperature, daily and annual thermal amplitude, and the general circulation of the atmosphere. This article aims to propose a new approach to the classification of the tropical zone on continents, distinguishing the globe into two domains: tropical and non-tropical, using three variables: annual average temperature, latitude, and altitude. A simplified model of the temperature-latitude relationship, called the trapezoidal model, was proposed, and using piecewise regression, the latitudinal thresholds dividing the globe into the two domains were obtained. The main result of this research is the proposition of mapping the tropics based on the definition that they have a low latitudinal variation in air temperature. In non-tropical regions, on the other hand, there is an inversely proportional linear relationship between temperature and latitude. Other results include: i) In the Southern Hemisphere, the limits are close to the Tropic of Capricorn, while in the Northern Hemisphere, the limits are south of the Tropic of Cancer at low altitudes and north at high altitudes. ii) Continental tropics in the Northern Hemisphere extend to higher latitudes compared to the Southern Hemisphere. iii) The trapezoidal model for describing global temperature allowed the calculation of latitudinal temperature gradients. iv) In the tropics, gradients are low (close to zero), whereas in non-tropical zones, gradients have similar averages (around 0.8°C/φ) but exhibit very different behaviors in the two hemispheres.