Geographical zone

Each of the five main latitude regions of the earth's surface is said to be a geographical zone, divided by the major circles of latitude. The differences between them relate to climate, and the behaviour of the sun. They are as follows:

*The North Frigid Zone, north of the Arctic Circle
*The North Temperate Zone, between the Arctic Circle and the Tropic of Cancer
*The Torrid Zone, between the Tropics of Cancer and Capricorn
*The South Temperate Zone, between the Tropic of Capricorn and the Antarctic Circle
*The South Frigid Zone, south of the Antarctic Circle

In the Torrid Zone, also known as the Tropics, the sun is directly overhead at least once during the year - at the edges of the tropics this occurs at the summer solstice, and over the equator, at the equinoxes. This is the hottest part of the earth, and there are two annual seasons: a dry and a wet. The Torrid Zone includes most of Africa, southern India, southern Asia, Indonesia, New Guinea, northern Australia, southern Mexico, Central America and northern South America.

In the two Temperate Zones, the sun is never directly overhead, and the climate is mild, generally ranging from warm to cool. The four annual seasons, Spring, Summer, Autumn and Winter occur in these areas. The North Temperate Zone includes Great Britain, Europe, northern Asia, North America and northern Mexico. The South Temperate Zone includes southern Australia, New Zealand, southern South America and South Africa.

The two Frigid Zones, or polar regions, experience the midnight sun and the polar night for part of the year - the edge of the zone experiences one day at the solstice when the sun doesn't rise or set for 24 hours, while in the centre of the zone (the pole), the day is literally one year long, with six months of daylight and six months of night. The Frigid Zones are the coldest parts of the earth, and are covered with ice and snow. The North Frigid Zone (the Arctic) includes northern Canada and Alaska, Greenland, northern Scandinavia, northern Russia, and the Arctic ice. The South Frigid Zone (The Antarctic) is filled by the continent of Antarctica; the next closest mainland is the southern tip of Chile and Argentina, followed by New Zealand.

The edges of the Temperate Zones are also sometimes referred to as the Subtropics, Subarctic and Subantarctic.

History

The idea of a geographical zone was first hypothesized by the ancient Greek scholar Aristotle. He said that the earth was divided into three types of climatic zones, based on their distance from the equator.

Thinking that the area near the equator was too hot for habitation, Aristotle dubbed the region around the equator (from 23.5° N to 23.5° S) as the "Torrid Zone." He reasoned that from the Arctic Circle to the pole was permanently frozen. He called this uninhabitable zone the "Frigid Zone." The only area that Aristotle believed was livable was the "Temperate Zone", lying between the "Frigid Zone" and the "Torrid Zone". One of the reasons Aristotle believed that the Temperate Zone was the best for life could come from the fact that he lived in that zone.

As knowledge of the earth's geography improved a second "Temperate Zone" was discovered south of the equator, and a second "Frigid Zone" was discovered around the Antarctic.

Aristotle's map was vastly oversimplified, although the general idea was correct. Today, the most commonly used climate map is the Köppen climate classification, developed by German climatologist and amateur botanist Wladimir Köppen (1846-1940), which divides the world into six major climate regions, based on average annual precipitation, average monthly precipitation, and average monthly temperature.

ee also

*Circles of latitude
*Climate classification
*Tropics
*Temperate
*Polar region