Geographical zone

Geographical zones are large regions on Earth defined by latitude. Latitude is the measurement of how far north or south a place is from the equator. These zones are divided by major circles of latitude. The primary reason these zones exist is because of differences in climate.

By looking at these zones, we can see how heat is distributed across our planet. This distribution is shown clearly in maps of annual average temperatures.

The movement of the Sun creates different heat zones. The most important mechanism is how the Sun's rays hit the Earth's surface. In the middle of the planet, the Sun can pass directly overhead. This creates a very hot area called the Torrid Zone. The Sun reaches its highest point, called the zenith, at different latitudes throughout the year. At the Tropic of Cancer, this happens once annually. At the Tropic of Capricorn, it also happens once per year. In the tropics proper, the Sun passes directly overhead twice every year.

There are five main geographical zones in total. The Torrid Zone, or the tropics, is the largest. It covers 39.78% of the Earth's surface. It sits between the Tropic of Cancer in the north and the Tropic of Capricorn in the south. Next are the two temperate zones. The North Temperate Zone and the South Temperate Zone each cover 25.99% of the Earth. Finally, there are the two frigid zones. The North Frigid Zone and the South Frigid Zone are the smallest. They each cover only 4.12% of the Earth's surface.

The Torrid Zone includes many diverse landmasses. It contains southern Mexico, Central America, and the Caribbean. It covers much of northern South America, including large parts of Brazil. Many African nations are here, such as Sudan, Egypt, and Libya. The zone also includes parts of the Middle East and the southern Indian subcontinent. In the Pacific, it covers most of Southeast Asia and much of Oceania. This includes Melanesia, Micronesia, and Polynesia. Even northern Australia and the island of New Guinea fall within this warm zone.

Temperate zones offer a much milder climate. In these regions, the Sun is never directly overhead. This results in weather that ranges from warm to cool. These zones are famous for having four distinct seasons. These seasons are spring, summer, autumn, and winter. The North Temperate Zone includes North America, Europe, and much of Northern Asia. It also covers North Africa and the northern Middle East. The South Temperate Zone includes southern Australia and New Zealand. It also includes much of southern South America and parts of Southern Africa.

The frigid zones are the coldest parts of the world. They are located at the North and South Poles. These areas are generally covered in ice and snow. Because they are far from the equator, they receive slanting rays from the Sun. These slanting rays provide less heat to the horizontal surface area. This makes the temperature very low. In these zones, people experience the midnight sun and the polar night. At the very center, the Sun stays up for six months and stays down for six months. The North Frigid Zone includes Alaska, Canada, Greenland, and Russia. The South Frigid Zone consists only of Antarctica.

Humans have studied these zones for thousands of years. The ancient Greek scholar Parmenides first hypothesized the idea of geographical zones. Later, the philosopher Aristotle modified this idea. Aristotle theorized three climatic zones based on distance from the equator. He called the central area the "Torrid Zone." He believed this area was too hot for humans to live in. He also thought the frigid zones were permanently frozen and uninhabitable. He believed only the temperate zones were suitable for life. As geography improved, humans discovered that people actually live in almost all climates. We learned about a second temperate zone and a second frigid zone as we explored the southern hemisphere.

Today, we use more complex systems to understand Earth's climate. One major system is the Köppen climate classification. This was developed by Wladimir Köppen, a Russian climatologist and botanist. His system divides the world into five major regions. It does this by looking at average annual precipitation and temperature. This is a more detailed way to study the Earth than the ancient Greek models. It helps us understand how moisture and heat work together to create different environments.