Northern Hemisphere

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 the Earth's axial tilt, 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 September 23 UTC). The dates vary each year due to the difference between the calendar year and the astronomical year.

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.[2]

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

Global hemispheres
Northern Hemisphere shaded blue. The hemispheres appear to be unequal in this image due to Antarctica not being shown, but in reality are the same size.
Northern Hemisphere Azimuthal projections
Northern Hemisphere from above the North Pole

Geography and climate

The Arctic is the region north of the Arctic Circle. Its climate is characterized by cold winters and cool summers. Precipitation mostly comes in the form of snow. The Arctic experiences 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 North Pole, which is the middle of the Northern Hemisphere.

Between the Arctic Circle and the Tropic of Cancer 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) 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. These are best seen in ocean circulation patterns in the North Atlantic and North Pacific oceans.

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 counter-clockwise pattern. Hurricanes and tropical storms (massive low-pressure systems) spin counter-clockwise in the Northern Hemisphere.

The shadow of a sundial moves clockwise in the Northern Hemisphere (opposite of the Southern Hemisphere). During the day, the Sun tends to rise to its maximum at a southerly position except between the Tropic of Cancer and the Equator, where the sun can be seen to the north, directly overhead, or to the south at noon dependent on the time of year.

When viewed from the Northern Hemisphere, the Moon appears inverted compared to a view from the Southern Hemisphere.[3][4] 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.

Demographics

The Northern Hemisphere is home to approximately 6.57 billion people which is around 90% of the earth's total human population of 7.3 billion people.[5][6]

List of continents

See also

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.
  2. ^ Life on Earth: A - G.. 1. ABC-CLIO. 2002. p. 528. ISBN 9781576072868. Retrieved 8 September 2016.
  3. ^ 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.
  4. ^ "Perspective of the Moon from the Northern and Southern Hemispheres". Retrieved 22 October 2013.
  5. ^ "90% Of People Live In The Northern Hemisphere - Business Insider". Business Insider. 4 May 2012. Retrieved 10 November 2015.
  6. ^ "GIC - Article". galegroup.com. Retrieved 10 November 2015.

External links

Media related to Northern Hemisphere at Wikimedia Commons

June

June is the sixth month of the year in the Julian and Gregorian calendars, the second of four months to have a length of 30 days, and the third of five months to have a length of less than 31 days. June contains the summer solstice in the Northern Hemisphere, the day with the most daylight hours, and the winter solstice in the Southern Hemisphere, the day with the fewest daylight hours (excluding polar regions in both cases). June in the Northern Hemisphere is the seasonal equivalent to December in the Southern Hemisphere and vice versa. In the Northern Hemisphere, the beginning of the traditional astronomical summer is 21 June (meteorological summer begins on 1 June). In the Southern Hemisphere, meteorological winter begins on 1 June.At the start of June, the sun rises in the constellation of Taurus; at the end of June, the sun rises in the constellation of Gemini. However, due to the precession of the equinoxes, June begins with the sun in the astrological sign of Gemini, and ends with the sun in the astrological sign of Cancer.

Martian dichotomy

The most conspicuous feature of Mars is a sharp contrast, known as the Martian dichotomy, between the Southern hemisphere and the Northern. The two hemispheres' geography differ in elevation by 1 to 3 km. The average thickness of the Martian crust is 45 km, with 32 km in the northern lowlands region, and 58 km in the southern highlands.

The boundary between the two regions is quite complex in places. One distinctive type of topography is called fretted terrain. It contains mesas, knobs, and flat-floored valleys having walls about a mile high. Around many of the mesas and knobs are lobate debris aprons that have been shown to be rock glaciers.Many large valleys formed by the lava erupted from the volcanoes of Mars cut through the dichotomy.The Martian dichotomy boundary includes the regions called Deuteronilus Mensae, Protonilus Mensae, and Nilosyrtis Mensae. All three regions have been studied extensively because they contain landforms believed to have been produced by the movement of ice or paleoshorelines questioned as formed by volcanic erosion.The northern lowlands comprise about one-third of the surface of Mars and are relatively flat, with as many impact craters as the southern hemisphere. The other two-thirds of the Martian surface are the highlands of the southern hemisphere. The difference in elevation between the hemispheres is dramatic. Three major hypotheses have been proposed for the origin of the crustal dichotomy: endogenic (by mantle processes), single impact, or multiple impact. Both impact-related hypotheses involve processes that could have occurred before the end of the primordial bombardment, implying that the crustal dichotomy has its origins early in the history of Mars.

Southern Hemisphere

The Southern Hemisphere is the half of Earth that is south of the Equator. It contains all or parts of five continents (Antarctica, Australia, about 90% of South America, a third of Africa, and several islands off the continental mainland of Asia), four oceans (Indian, South Atlantic, Southern, and South Pacific) 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.Owing to the tilt of Earth's rotation relative to the Sun and the ecliptic plane, summer is from December to March and winter is from June to September. September 22 or 23 is the vernal equinox and March 20 or 21 is the autumnal equinox. The South Pole is in the center of the southern hemispherical region.

Spring (season)

Spring is one of the four temperate seasons, following winter and preceding summer. There are various technical definitions of spring, but local usage of the term varies according to local climate, cultures and customs. When it is spring in the Northern Hemisphere, it is autumn in the Southern Hemisphere and vice versa. At the spring (or vernal) equinox, days and nights are approximately twelve hours long, with day length increasing and night length decreasing as the season progresses.

Spring and "springtime" refer to the season, and also to ideas of rebirth, rejuvenation, renewal, resurrection and regrowth. Subtropical and tropical areas have climates better described in terms of other seasons, e.g. dry or wet, monsoonal or cyclonic. Cultures may have local names for seasons which have little equivalence to the terms originating in Europe.

Time in Peru

Peru Time (PET) is the official time in Peru. It is always 5 hours behind Coordinated Universal Time (UTC−05:00). Peru has only one time zone and does not observe daylight saving time. During the winter (summer in the Northern Hemisphere), Peruvian Time is the same as North American Central Time, while during the summer (winter in the Northern Hemisphere) it is akin to Eastern Time.

Winter

Winter is the coldest season of the year in polar and temperate zones (winter does not occur in most of the tropical zone). It occurs after autumn and before spring in each year. Winter is caused by the axis of the Earth in that hemisphere being oriented away from the Sun. Different cultures define different dates as the start of winter, and some use a definition based on weather. When it is winter in the Northern Hemisphere, it is summer in the Southern Hemisphere, and vice versa. In many regions, winter is associated with snow and freezing temperatures. The moment of winter solstice is when the Sun's elevation with respect to the North or South Pole is at its most negative value (that is, the Sun is at its farthest below the horizon as measured from the pole). The day on which this occurs has the shortest day and the longest night, with day length increasing and night length decreasing as the season progresses after the solstice. The earliest sunset and latest sunrise dates outside the polar regions differ from the date of the winter solstice, however, and these depend on latitude, due to the variation in the solar day throughout the year caused by the Earth's elliptical orbit (see earliest and latest sunrise and sunset).

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