Tropics
The region between the Tropic of Cancer and Tropic of Capricorn.
The tropics are the region of Earth surrounding the equator, where the Sun may shine directly overhead. This contrasts with the temperate or polar regions, where the Sun can never be directly overhead. Because of Earth's axial tilt, the width of the tropics (in latitude) is twice the tilt. The tropics are also referred to as the tropical zone and the torrid zone. Due to the sun's high angle throughout the year, the tropics receive the most solar energy over the course of the year and consequently have the highest temperatures on the planet. The tropics also have the lowest seasonal variation; 'winter' and 'summer' lose their temperature contrast, and seasons are more commonly divided by precipitation variations.
- area_percentage_of_earth_surface
- 39.8%
- landmass_percentage
- 36%
- population_percentage_as_of_2014
- 40%
- projected_population_percentage_by_2050
- 50%
- axial_tilt_current
- 23.4°
- northern_boundary
- Tropic of Cancer (23°26′09.0″ N)
- southern_boundary
- Tropic of Capricorn (23°26′09.0″ S)
Lore & Background
The word 'tropic' comes via Latin from Ancient Greek τροπή (tropē), meaning 'to turn' or 'change direction'. This lent to the marginal parallels where the Sun would be highest overhead as the Earth tilts while still facing the Sun the most, at certain times of the year: the Tropic of Cancer was the parallel where the Sun's position was at its highest during summer in the Northern Hemisphere against where constellation Cancer formerly had been measured as far back in Mesopotamia c. This is no longer the case due to the precession of the equinoxes where overhead positions now lay against the backdrop of Taurus and Sagittarius respectively.
Reader's Guide
The tropics are defined astronomically as the region between the Tropic of Cancer in the Northern Hemisphere at 23°26′09.0″ N and the Tropic of Capricorn in the Southern Hemisphere at 23°26′09.0″ S; these latitudes correspond to the axial tilt of the Earth. The tropical zone includes everywhere on Earth which is a subsolar point at least once during the solar year. The tropics constitute 39.8% of Earth's surface area and contain 36% of Earth's landmass. Because of global warming, the weather conditions of the tropics are expanding with areas in the subtropics, having more extreme weather events such as heatwaves and more intense storms. These changes may make certain parts of the tropics uninhabitable. The tropics maintain wide diversity of local climates, such as rain forests, monsoons, savannahs, deserts, and high altitude snow-capped mountains. The word 'tropical' can specifically refer to certain kinds of weather, rather than to the geographic region; these usages ought not be confused.
Did You Know?
- The tropics are defined as the region between the Tropic of Cancer and the Tropic of Capricorn, which correspond to Earth's axial tilt of about 23.4°.
- The tropics receive the most solar energy over the course of the year and have the highest temperatures on the planet.
- The word 'tropic' comes from the Greek word τροπή (tropē), meaning 'to turn' or 'change direction'.
Frequently Asked Questions
What is the Tropics in physical geography?
The Tropics refer to the latitudinal band on Earth that wraps around the equator, bounded by the Tropic of Cancer to the north and the Tropic of Capricorn to the south. It is the only zone where the Sun can pass directly overhead at some point in the year, which is why it is also called the torrid zone.
What determines the width of the Tropics?
The total north-to-south span of the tropical zone equals exactly twice Earth's current axial tilt of 23.4°, placing the northern boundary at 23°26′09.0″ N. If the tilt were to change over geologic time, the tropical band would widen or narrow accordingly.
Why are the Tropics the hottest region on Earth?
Because the Sun's angle of incidence stays high throughout the entire year, this latitudinal band absorbs more solar energy per unit area than any other zone. It also shows the smallest seasonal temperature variation of any major climate region.
How do the Tropics differ from the temperate and polar zones?
The defining distinction is that the Sun can reach a position directly overhead somewhere within the tropical band, while it never does so at temperate or polar latitudes. This fundamental difference in solar geometry is what drives the tropics' consistently higher temperatures and lower seasonal swings.
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