Northern Hemisphere

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Coordinates: 90°0′0″N0°0′0″E / 90.00000°N 0.00000°E / 90.00000; 0.00000

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Northern Hemisphere shaded blue. The hemispheres appear unequal here because Antarctica is not shown. Global hemispheres.svg
Northern Hemisphere shaded blue. The hemispheres appear unequal here because Antarctica is not shown.
Northern Hemisphere from above the North Pole Northern Hemisphere LamAz.png
Northern Hemisphere from above the North Pole

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. [1]

Owing to Earth's axial tilt of 23.439281°, winter in the Northern Hemisphere lasts from the December solstice (typically December 21 UTC) to the March equinox (typically March 20 UTC), while summer lasts from the June solstice through to the September equinox (typically on 23 September UTC). The dates vary each year due to the difference between the calendar year and the astronomical year. Within the Northern Hemisphere, oceanic currents can change the weather patterns that affect many factors within the north coast. Such events include El Niño–Southern Oscillation.

Trade winds blow from east to west just above the equator. The winds pull surface water with them, creating currents, which flow westward due to the Coriolis effect. The currents then bend to the right, heading north. At about 30 degrees north latitude, a different set of winds, the westerlies, push the currents back to the east, producing a closed clockwise loop. [2]

Its surface is 60.7% water, compared with 80.9% water in the case of the Southern Hemisphere, and it contains 67.3% of Earth's land. [3] Europe and North America are entirely on Earth's Northern Hemisphere.

Geography and climate

Northern hemisphere glaciation during the last ice ages. The setup of 3 to 4 kilometer thick ice sheets caused a sea level lowering of about 120 m. Northern icesheet hg.png
Northern hemisphere glaciation during the last ice ages. The setup of 3 to 4 kilometer thick ice sheets caused a sea level lowering of about 120 m.
Canadian Rockies in North America Snow covered mountains in Mount Robson (Unsplash).jpg
Canadian Rockies in North America

During the 2.5 million years of the Pleistocene, numerous cold phases called glacials (Quaternary ice age), or significant advances of continental ice sheets, in Europe and North America, occurred at intervals of approximately 40,000 to 100,000 years. The long glacial periods were separated by more temperate and shorter interglacials which lasted about 10,000–15,000 years. The last cold episode of the last glacial period ended about 10,000 years ago. [4] Earth is currently in an interglacial period of the Quaternary, called the Holocene. [5] The glaciations that occurred during the glacial period covered many areas of the Northern Hemisphere.

The Arctic is a region around the North Pole (90° latitude). Its climate is characterized by cold winters and cool summers. Precipitation mostly comes in the form of snow. Areas inside the Arctic Circle (66°34′ latitude) experience some days in summer when the Sun never sets, and some days during the winter when it never rises. The duration of these phases varies from one day for locations right on the Arctic Circle to several months near the Pole, which is the middle of the Northern Hemisphere.

Between the Arctic Circle and the Tropic of Cancer (23°26′ latitude) lies the Northern temperate zone. The changes in these regions between summer and winter are generally mild, rather than extreme hot or cold. However, a temperate climate can have very unpredictable weather.

Tropical regions (between the Tropic of Cancer and the Equator, 0° latitude) are generally hot all year round and tend to experience a rainy season during the summer months, and a dry season during the winter months.

In the Northern Hemisphere, objects moving across or above the surface of the Earth tend to turn to the right because of the Coriolis effect. As a result, large-scale horizontal flows of air or water tend to form clockwise-turning gyres. [6] These are best seen in ocean circulation patterns in the North Atlantic and North Pacific oceans.[ citation needed ] Within the Northern Hemisphere, oceanic currents can change the weather patterns that affect many factors within the north coast; such as El Niño. [ citation needed ]

For the same reason, flows of air down toward the northern surface of the Earth tend to spread across the surface in a clockwise pattern. Thus, clockwise air circulation is characteristic of high pressure weather cells in the Northern Hemisphere. Conversely, air rising from the northern surface of the Earth (creating a region of low pressure) tends to draw air toward it in a counterclockwise pattern. Hurricanes and tropical storms (massive low-pressure systems) spin counterclockwise in the Northern Hemisphere. [7]

The shadow of a sundial moves clockwise on latitudes north of the subsolar point and anticlockwise to the south. During the day at these latitudes, the Sun tends to rise to its maximum at a southerly position. Between the Tropic of Cancer and the Equator, the sun can be seen to the north, directly overhead, or to the south at noon, dependent on the time of year. In the Southern Hemisphere, the midday Sun is predominantly in the north.

When viewed from the Northern Hemisphere, the Moon appears inverted compared to a view from the Southern Hemisphere. [8] [9] The North Pole faces away from the galactic center of the Milky Way. This results in the Milky Way being sparser and dimmer in the Northern Hemisphere compared to the Southern Hemisphere, making the Northern Hemisphere more suitable for deep-space observation, as it is not "blinded" by the Milky Way.[ citation needed ]

Demographics

As of 2015, the Northern Hemisphere is home to approximately 6.4 billion people which is around 87.0% of the earth's total human population of 7.3 billion people. [10] [11] [12]

List of Continents, countries or territories, and oceans in the Northern Hemisphere

Continents
Africa Asia Americas Europe
about two-thirds, from north of Libreville in Gabon in the west to north of Mogadishu in Somalia in the east.the entire continental mainland. Part of Indonesia, and 24 out of 26 atolls of Maldives in the Indian Ocean, are also in the Northern Hemisphere.all of North America, Central America, and the Caribbean islands. About one-fifth of South America, from north of Quito in Ecuador in the west to north of the Amazon River mouth in Brazil in the east.entirely in the Northern Hemisphere [note 1]
Countries or Territories
Africa Asia Americas Europe [note 1]
Entirely
Mostly
Partly
Entirely
Mostly
Partly
Entirely
Mostly
Partly
Entirely
Mostly
Ocean
Arctic Atlantic Indian Pacific
Entirely
Entirely
Mostly
Entirely
Mostly
Entirely
Mostly
Partly

See also

Related Research Articles

<span class="mw-page-title-main">Ice age</span> Period of long-term reduction in temperature of Earths surface and atmosphere

An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and greenhouse periods, during which there are no glaciers on the planet. Earth is currently in the Quaternary glaciation. Individual pulses of cold climate within an ice age are termed glacial periods, and intermittent warm periods within an ice age are called interglacials or interstadials.

<span class="mw-page-title-main">Polar climate</span> Climate Classification

The polar climate regions are characterized by a lack of warm summers but with varying winters. Every month in a polar climate has an average temperature of less than 10 °C (50 °F). Regions with polar climate cover more than 20% of the Earth's area. Most of these regions are far from the equator and near the poles, and in this case, winter days are extremely short and summer days are extremely long. A polar climate consists of cool summers and very cold winters, which results in treeless tundra, glaciers, or a permanent or semi-permanent layer of ice. It is identified with the letter E in the Köppen climate classification.

<span class="mw-page-title-main">Temperate climate</span> Main climate class

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 changes.

<span class="mw-page-title-main">Tropic of Cancer</span> Line of northernmost latitude at which the Sun can be directly overhead

The Tropic of Cancer, which is also referred to 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′10.7″ (or 23.43632°) north of the Equator.

<span class="mw-page-title-main">Tropic of Capricorn</span> Line of southernmost latitude at which the sun can be directly overhead

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.

<span class="mw-page-title-main">Circumpolar star</span> Star that never sets due to its apparent proximity to a celestial pole

A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest pole for the entire night on every night of the year. Others are called seasonal stars.

<span class="mw-page-title-main">Circle of latitude</span> Geographic notion

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.

<span class="mw-page-title-main">Southern Hemisphere</span> Half of Earth that is south of the Equator

The Southern Hemisphere is the half (hemisphere) of Earth that is south of the Equator. It contains all or parts of five continents and four oceans, as well as New Zealand and most of the Pacific Islands in Oceania. Its surface is 80.9% water, compared with 60.7% water in the case of the Northern Hemisphere, and it contains 32.7% of Earth's land.

<span class="mw-page-title-main">Physical oceanography</span> Study of physical conditions and physical processes within the ocean

Physical oceanography is the study of physical conditions and physical processes within the ocean, especially the motions and physical properties of ocean waters.

<span class="mw-page-title-main">Atmospheric circulation</span> Process which distributes thermal energy about the Earths surface

Atmospheric circulation is the large-scale movement of air and together with ocean circulation is the means by which thermal energy is redistributed on the surface of the Earth. The Earth's atmospheric circulation varies from year to year, but the large-scale structure of its circulation remains fairly constant. The smaller scale weather systems – mid-latitude depressions, or tropical convective cells – occur chaotically, and long-range weather predictions of those cannot be made beyond ten days in practice, or a month in theory.

<span class="mw-page-title-main">High-pressure area</span> In meteorology, an anticyclone

A high-pressure area, high, or anticyclone, is an area near the surface of a planet where the atmospheric pressure is greater than the pressure in the surrounding regions. Highs are middle-scale meteorological features that result from interplays between the relatively larger-scale dynamics of an entire planet's atmospheric circulation.

<span class="mw-page-title-main">Westerlies</span> Prevailing winds from the west

The westerlies, anti-trades, or prevailing westerlies, are prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes and trend towards the poles and steer extratropical cyclones in this general manner. Tropical cyclones which cross the subtropical ridge axis into the westerlies recurve due to the increased westerly flow. The winds are predominantly from the southwest in the Northern Hemisphere and from the northwest in the Southern Hemisphere.

The Holocene Climate Optimum (HCO) was a warm period that occurred in the interval roughly 9,000 to 5,000 years ago BP, with a thermal maximum around 8000 years BP. It has also been known by many other names, such as Altithermal, Climatic Optimum, Holocene Megathermal, Holocene Optimum, Holocene Thermal Maximum, Hypsithermal, and Mid-Holocene Warm Period.

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.

<span class="mw-page-title-main">Quaternary glaciation</span> Series of alternating glacial and interglacial periods

The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial and interglacial periods during the Quaternary period that began 2.58 Ma and is ongoing. Although geologists describe this entire period up to the present as an "ice age", in popular culture this term usually refers to the most recent glacial period, or to the Pleistocene epoch in general. Since Earth still has polar ice sheets, geologists consider the Quaternary glaciation to be ongoing, though currently in an interglacial period.

The five main latitude regions of Earth's surface comprise geographical zones, divided by the major circles of latitude. The differences between them relate to climate. They are as follows:

  1. The North Frigid Zone, between the North Pole at 90° N and the Arctic Circle at 66°33′48.7" N, covers 4.12% of Earth's surface.
  2. The North Temperate Zone, between the Arctic Circle at 66°33′48.7" N and the Tropic of Cancer at 23°26'11.3" N, covers 25.99% of Earth's surface.
  3. The Torrid Zone, between the Tropic of Cancer at 23°26'11.3" N and the Tropic of Capricorn at 23°26'11.3" S, covers 39.78% of Earth's surface.
  4. The South Temperate Zone, between the Tropic of Capricorn at 23°26'11.3" S and the Antarctic Circle at 66°33'48.7" S, covers 25.99% of Earth's surface.
  5. The South Frigid Zone, from the Antarctic Circle at 66°33'48.7" S and the South Pole at 90° S, covers 4.12% of Earth's surface.
<span class="mw-page-title-main">Sun path</span> Arc-like path that the Sun appears to follow across the sky

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.

<span class="mw-page-title-main">Equator</span> Line halfway between North and South poles

The equator is a circle of latitude, about 40,075 km (24,901 mi) in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles.

<span class="mw-page-title-main">Antarctic Circle</span> Boundary of the Antarctic

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.

<span class="mw-page-title-main">Periglaciation</span>

Periglaciation describes geomorphic processes that result from seasonal thawing of snow in areas of permafrost, the runoff from which refreezes in ice wedges and other structures. "Periglacial" suggests an environment located on the margin of past glaciers. However, freeze and thaw cycles influence landscapes outside areas of past glaciation. Therefore, periglacial environments are anywhere that freezing and thawing modify the landscape in a significant manner.

References

  1. Archinal, Brent A.; A'Hearn, Michael F.; Bowell, Edward G.; Conrad, Albert R.; Consolmagno, Guy J.; et al. (2010). "Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2009" (PDF). Celestial Mechanics and Dynamical Astronomy. 109 (2): 101–135. Bibcode:2011CeMDA.109..101A. doi:10.1007/s10569-010-9320-4. S2CID   189842666. Archived from the original (PDF) on 2016-03-04. Retrieved 2018-09-26.
  2. Society, National Geographic (2019-07-01). "Ocean Currents". National Geographic Society. Retrieved 2020-10-16.
  3. Life on Earth: A – G.. 1. ABC-CLIO. 2002. p. 528. ISBN   9781576072868 . Retrieved 8 September 2016.
  4. "Quaternary Period". National Geographic. 2017-01-06.
  5. "How long can we expect the present Interglacial period to last?". U.S. Department of the Interior.
  6. US Department of Commerce, National Oceanic and Atmospheric Administration. "Boundary Currents – Currents: NOAA's National Ocean Service Education". oceanservice.noaa.gov. Retrieved 2020-07-31.
  7. "Hurricanes: Science and Society: Primary Circulation". www.hurricanescience.org. Retrieved 2021-08-11.
  8. Laura Spitler. "Does the Moon look different in the northern and southern hemispheres? (Beginner) – Curious About Astronomy? Ask an Astronomer". cornell.edu. Retrieved 10 November 2015.
  9. "Perspective of the Moon from the Northern and Southern Hemispheres". Archived from the original on 9 September 2017. Retrieved 22 October 2013.
  10. Calculated from World Population Yearbook 2019(in thousands) World total population: 7,359,970 Northern Hemisphere population: 6,405,030 87.0% Southern Hemisphere population: 954,940 13.0% Note 1) If there is no data for 2019, the latest data was used. Note 2) Countries with land that straddles the equator are divided into half populations in each of the Northern and Southern Hemispheres.
  11. "90% Of People Live In The Northern Hemisphere – Business Insider". Business Insider. 4 May 2012. Retrieved 10 November 2015.
  12. "GIC – Article". galegroup.com. Retrieved 10 November 2015.
  1. 1 2 The continent itself is entirely within the Northern Hemisphere. However, some overseas territories of the countries of France and the United Kingdom are in the Southern Hemisphere.

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