The North Temperate Zone, between the Arctic Circle at 66°33′49.9″ N and the Tropic of Cancer at 23°26′10.1″ N, covers 25.99% of Earth's surface.
The Torrid Zone, between the Tropic of Cancer at 23°26′10.1″ N and the Tropic of Capricorn at 23°26′10.1″ S, covers 39.78% of Earth's surface.
The South Temperate Zone, between the Tropic of Capricorn at 23°26′10.1″ S and the Antarctic Circle at 66°33′49.9″ S, covers 25.99% of Earth's surface.
The South Frigid Zone, from the Antarctic Circle at 66°33′49.9″ S and the South Pole at 90° S, covers 4.12% of Earth's surface.
Earth's climatic zones
Ice cap
Tundra
Boreal
Warm temperate
Subtropical
Tropical
On the basis of latitudinal extent, the globe is divided into three broad heat zones.
Torrid Zone
The Torrid Zone is also known as the tropics. This zone is bounded on the north by the Tropic of Cancer and on the south by the Tropic of Capricorn; these latitudes mark the northern and southern extremes in which the Sun passes[lower-alpha 1] directly overhead. This happens once annually on these cusps, but in the tropics proper, the Sun passes overhead twice a year.
Within the northern tropics, the Sun passes overhead its first time for that year before the June solstice, at which time it does so as to the Tropic of Cancer. It passes over these latitudes in turn again, on its apparent southward journey, to and before the September equinox. After then, the center of the Sun at the high point, the zenith, of the sky (which makes for the subsolar point beneath) aligns with successive latitudes in the southern tropics. The Sun passes overhead of these then does so once per year for the Tropic of Capricorn at the December solstice, then passes back again over those latitudes to return to the equator for the March equinox.
In the two temperate zones, consisting of the tepidlatitudes, 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 South Temperate Zone includes Southern Australia (the southern regions of the Australian states of Western Australia and Queensland, the southern regions of the Northern Territory, and the entire territories of the states of New South Wales, South Australia, Tasmania and Victoria), great part of Zealandia (New Zealand), southern South America (large part of the Southern Cone), and Southern Africa (southern Namibia, southern Botswana, great part of South Africa, the entire territories of Lesotho and Eswatini, and the southern tips of Mozambique and Madagascar).
Frigid zones
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 remains one day, the winter solstice, when the Sun is too low to rise, and one day at the summer solstice when the Sun remains above the horizon for 24 hours. In the center of the zone (the pole), the day is one year long, with six months of daylight and six months of night. The frigid zones are the coldest regions of Earth and are generally covered in ice and snow. It receives slanting rays of the Sun, as this region lies farthest from the equator. Summer in this region lasts for about 2 to 3 months, and there is almost 24-hour sunlight during summer. The sun's rays are always slanting, so provide less heat per horizontal surface area.
The concept of a geographical zone was first hypothesized by the ancient Greek scholar Parmenides[2] and lastingly modified by Aristotle.[3] Both philosophers theorized the Earth divided into three types of climatic zones based on their distance from the equator.
Like Parmeneides, 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." Both philosophers reasoned the region from the Arctic Circle to the pole to be permanently frozen. This region thought uninhabitable, was called the "Frigid Zone." The only area believed to be habitable was the northern "Temperate Zone" (the southern one not having been discovered), lying between the "Frigid Zones" 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. Although Aristotle's map was oversimplified, 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.
↑ Strab. 2,2,1-2 in: A. H. Coxon and R. D. McKirahan (eds), The Fragments of Parmenides: A Critical Text With Introduction, and Translation, the Ancient Testimonia and a Commentary, 2nd edn (Phresis: Supplementary Volumes 3; Assen, Dover (NH), 2009), p. 160.
↑ The "Sun passing", "reaching" or similar, implying a movement of the sun, is – in the widest context – conflating subject with object. Astronomy, although it treats the Sun from the Earth's perspective with global, cyclical, limited northward and southern migration (in the sky, the celestial sphere), proves this is due to Earth's axial tilt, and its unlimited east-west movement is due to the Earth's orbit. If seeing and analyzing Earth and the Sun in space, Earth moves such that a geographical zone faces the Sun more or less at a certain date, or moves to align beneath the Sun, due to tilt, a particular latitude.
The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the Solar System as Earth's North Pole.
A solstice is an event that occurs when the Sun reaches its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. Two solstices occur annually, around June 21 and December 21. In many countries, the seasons of the year are determined by the solstices and the equinoxes.
In geography, the temperate climates of Earth occur in the middle latitudes, which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout the year and more distinct seasonal changes compared to tropical climates, where such variations are often small and usually only have precipitation differences.
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at 23°26′10.1″ (or 23.43614°) N and the Tropic of Capricorn in the Southern Hemisphere at 23°26′10.1″ (or 23.43614°) S. The tropics are also referred to as the tropical zone and the torrid zone.
The Tropic of Cancer, also known as the Northern Tropic, is the most northerly circle of latitude on Earth at which the Sun can be directly overhead. This occurs on the June solstice, when the Northern Hemisphere is tilted toward the Sun to its maximum extent. It also reaches 90 degrees below the horizon at solar midnight on the December Solstice. Using a continuously updated formula, the circle is currently 23°26′10.1″ (or 23.43614°) north of the Equator.
The Tropic of Capricorn is the circle of latitude that contains the subsolar point at the December solstice. It is thus the southernmost latitude where the Sun can be seen directly overhead. It also reaches 90 degrees below the horizon at solar midnight on the June Solstice. Its northern equivalent is the Tropic of Cancer.
A circle of latitude or line of latitude on Earth is an abstract east–west small circle connecting all locations around Earth at a given latitude coordinate line.
A polar circle is a geographic term for a conditional circular line (arc) referring either to the Arctic Circle or the Antarctic Circle. These are two of the keynote circles of latitude (parallels). On Earth, the Arctic Circle is currently drifting northwards at a speed of about 14.5 m per year and is now at a mean latitude of 66°33′49.9″ N; the Antarctic Circle is currently drifting southwards at a speed of about 14.5 m per year and is now at a mean latitude of 66°33′49.9″ S. Polar circles are often equated with polar regions of Earth. Due to their inherent climate environment, the bulk of the Arctic Circle, much of which is sea, is sparsely settled whereas this applies to all of Antarctica which is mainly land and sheltered ice shelves.
The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from 23°26′10.1″ (or 23.43615°) to approximately 35° north and south. The horse latitudes lie within this range.
The polar regions, also called the frigid zones or polar zones, of Earth are Earth's polar ice caps, the regions of the planet that surround its geographical poles, lying within the polar circles. These high latitudes are dominated by floating sea ice covering much of the Arctic Ocean in the north, and by the Antarctic ice sheet on the continent of Antarctica and the Southern Ocean in the south.
The middle latitudes are a spatial region on Earth located between the Tropic of Cancer to the Arctic Circle (66°33'39"), and Tropic of Capricorn (-23°26'22") to the Antarctic Circle (-66°33'39"). They include Earth's subtropical and temperate zones, which lie between the two tropics and the polar circles. Weather fronts and extratropical cyclones are usually found in this area, as well as occasional tropical cyclones or subtropical cyclones, which have traveled from their areas of formation closer to the Equator.
The climes in classical Greco-Roman geography and astronomy were the divisions of the inhabited portion of the spherical Earth by geographic latitude.
Rainfall and the tropical climate dominate the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year, roughly following the solar equator. The tropical rain belt is an area of active rain that is positioned mostly around the tropics.
Daytime as observed on Earth is the period of the day during which a given location experiences natural illumination from direct sunlight. Daytime occurs when the Sun appears above the local horizon, that is, anywhere on the globe's hemisphere facing the Sun. In direct sunlight the movement of the sun can be recorded and observed using a sundial that casts a shadow that slowly moves during the day. Other planets and natural satellites that rotate relative to a luminous primary body, such as a local star, also experience daytime, but this article primarily discusses daytime on Earth.
Sun path, sometimes also called day arc, refers to the daily and seasonal arc-like path that the Sun appears to follow across the sky as the Earth rotates and orbits the Sun. The Sun's path affects the length of daytime experienced and amount of daylight received along a certain latitude during a given season.
The equator is a circle of latitude that divides a spheroid, such as Earth, into the Northern and Southern hemispheres. On Earth, the Equator is an imaginary line located at 0 degrees latitude, about 40,075 km (24,901 mi) in circumference, halfway between the North and South poles. The term can also be used for any other celestial body that is roughly spherical.
A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's tilted orbit around the Sun. In temperate and polar regions, the seasons are marked by changes in the intensity of sunlight that reaches the Earth's surface, variations of which may cause animals to undergo hibernation or to migrate, and plants to be dormant. Various cultures define the number and nature of seasons based on regional variations, and as such there are a number of both modern and historical cultures whose number of seasons varies.
The solar equator is the latitude on Earth at which the Sun is observed directly overhead at midday. Due to the obliquity of Earth's axis, the solar equator varies during the year, from the Tropic of Capricorn on the December solstice to the Tropic of Cancer on the June solstice. On the day of either equinox, the Sun's position is at the zenith when viewed from the geographic equator. The Sun can never be observed directly overhead from outside of the tropics.
The Antarctic Circle is the most southerly of the five major circles of latitude that mark maps of Earth. The region south of this circle is known as the Antarctic, and the zone immediately to the north is called the Southern Temperate Zone. South of the Antarctic Circle, the Sun is above the horizon for 24 continuous hours at least once per year and the centre of the Sun is below the horizon for 24 continuous hours at least once per year ; this is also true within the equivalent polar circle in the Northern Hemisphere, the Arctic Circle.
The Arctic Circle is one of the two polar circles, and the most northerly of the five major circles of latitude as shown on maps of Earth at about 66° 34' N. Its southern equivalent is the Antarctic Circle.
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