Nepedia
Back to Discover
Advanced Reader
🗺️

Tropics

geography Maturity 5-7 Next article →

The tropics are a massive geographic region surrounding the Earth's equator. This zone is defined by the sun's position in the sky. It is the area where the sun can shine directly overhead at least once a year.

World map indicating tropics and subtropics
World map indicating tropics and subtropics

Because of this high sun angle, the tropics receive more solar energy than any other region. This constant energy makes the tropics the hottest part of our planet. The region is quite large, covering 39.8% of the Earth's total surface area. It also contains 36% of the world's landmass.

axial tilt vs tropical and polar circles
axial tilt vs tropical and polar circles

The boundaries of the tropics are created by the Earth's axial tilt. The Earth is tilted at an angle of approximately 23.4 degrees. This tilt creates two specific lines of latitude that mark the edges of the tropical zone. The northern boundary is known as the Tropic of Cancer. The southern boundary is known as the Tropic of Capricorn.

axial tilt vs tropical and polar circles
axial tilt vs tropical and polar circles

These lines represent the northernmost and southernmost latitudes where the sun can ever be seen directly overhead. As the Earth's tilt changes over time, these tropical circles also shift. The term "tropic" comes from the Ancient Greek word meaning "to turn" or "to change direction." This refers to how the sun's position changes as the Earth tilts throughout the year.

Climate in the tropics works differently than in temperate or polar regions. In those other areas, seasons are defined by changes in temperature and daylight. In the tropics, temperature variation is very low throughout the year. Instead, seasons are usually defined by precipitation, or rainfall. Many tropical areas experience a distinct wet season and a dry season.

Monthly zonal mean precipitation
Monthly zonal mean precipitation

The wet season, sometimes called the green season, brings most of the annual rainfall. During this time, heavy rains can cause rivers to overflow their banks. This flooding can lead to soil erosion and increased instances of malaria. However, the rain also improves air and water quality and helps vegetation grow rapidly.

While many think of the tropics as purely wet, the region contains many different climates. The tropics maintain a wide diversity of local environments. You can find lush rainforests and seasonal tropical forests. There are also wide savannahs, grasslands, and even deserts.

Tropical wet forests
Tropical wet forests

For example, the Sahara Desert and the Atacama Desert are located within the geographical tropics but are classified as dry or arid. You can even find high-altitude, snow-capped mountains like Mount Kilimanjaro or the Andes within these latitudes. This diversity means the tropics are not just one single type of environment.

The biological diversity in the tropics is incredibly high. Biogeographers divide the tropics into two main areas: the Paleotropics and the Neotropics. The Paleotropics include Africa, Asia, and Australia. The Neotropics include Central America, South America, and the Caribbean.

Tropical wet forests
Tropical wet forests

Together, these regions are sometimes called the Pantropic. Many species in these areas are endemic, meaning they are found nowhere else on Earth. This is especially true in rainforests like the Amazon or the forests of Madagascar. Many important plants originate here, including cacao, coffee, rubber trees, and many citrus fruits.

Humanity is deeply connected to the tropical regions. Currently, 40% of the world's population lives in the tropics. This number is projected to reach 50% by the year 2050. Because so many people live here, changes in the environment are very important. However, the tropics are currently facing challenges from global warming. The region has warmed by 0.7 to 0.8 degrees Celsius over the last century. Scientists predict further warming of 1 to 4 degrees Celsius by the year 2100.

Kota Kinabalu by Dale Preston
Kota Kinabalu by Dale Preston

This warming can cause more intense storms and heatwaves, which may make some areas uninhabitable.

Historically, people have held many different views of the tropics. This concept is often called "tropicality." Some people viewed the tropics as a "Garden of Eden" or a tropical paradise. Others saw the region as a wild and unconquerable nature.

Juruá River in Brazil
Juruá River in Brazil

In the past, some Western scholars even theorized that the hot, humid climate made the regions less suitable for human civilization. Today, these views are being replaced by more sophisticated scientific understandings. We now recognize the tropics as a complex and vital system for the entire planet's health.

696 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (8)
File:World map indicating tropics and subtropics.png
World map indicating tropics and subtropics.png
File:Koppen-Geiger Map v2 A 1991–2020.svg
Koppen-Geiger Map v2 A 1991–2020.svg
File:axial_tilt_vs_tropical_and_polar_circles.svg
axial_tilt_vs_tropical_and_polar_circles.svg
File:Bora Bora.jpg
Bora Bora.jpg
File:Kota Kinabalu by Dale Preston.jpg
Kota Kinabalu by Dale Preston.jpg
File:Monthly zonal mean precipitation.png
Monthly zonal mean precipitation.png
File:Tropical wet forests.svg
Tropical wet forests.svg
File:Juruá River in Brazil.jpg
Juruá River in Brazil.jpg
More to explore

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.