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The five main latitude regions of the Earth's surface comprise geographical zones, divided by the major circles of latitude. The differences between them relate to climate. 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 Tropical Circles
- The South Temperate Zone, between the Tropic of Capricorn and the Antarctic Circle
- The South Frigid Zone, south of the Antarctic Circle
The apparent movement of the Sun
In the Torrid or tropical Zone, also known as the Tropic, the Sun is directly overhead at least once during the year. In the Northern Hemisphere, the overhead Sun moves north from the Equator until it reaches 23.5 degrees North (Tropic of Cancer) at the June solstice, after which it moves back south to the Equator. In the Southern Hemisphere, the overhead Sun moves south from the Equator until it reaches 23.5 degrees South (Tropic of Capricorn) at the December solstice, after which it moves back north to the Equator.
In the two Temperate Zones, consisting of the tepid latitudes, 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 Southern Africa.
The two Frigid Zones, or polar regions, experience the midnight sun and the polar night for part of the year - at the edge of the zone there is one day at the winter solstice when the Sun does not 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 Zone is the coldest parts of the earth, and is generally covered with ice and snow.
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) 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 liveable was the "Temperate Zone", lying between the "Frigid Zone" and the "Torrid Zone". However, humans have inhabited almost all climates on Earth, including inside the Arctic Circle.
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 oversimplistic, although the general idea was correct. Today, the most commonly used climate map is the Köppen climate classification, developed by Russian climatologist of German descent and amateur botanist Wladimir Köppen (1846–1940), which divides the world into five major climate regions, based on average annual precipitation, average monthly precipitation, and average monthly temperature.