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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.
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 on 23 September 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.
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. These are best seen in ocean circulation patterns in the North Atlantic and North Pacific oceans.[ 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 counter-clockwise pattern. Hurricanes and tropical storms (massive low-pressure systems) spin counter-clockwise in the Northern Hemisphere.[ citation needed ]
The shadow of a sundial moves clockwise on latitudes north of the subsolar point. During the day on 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 at north.
When viewed from the Northern Hemisphere, the Moon appears inverted compared to a view from the Southern Hemisphere. [ citation needed ]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.
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.
Earth's Northern Hemisphere comprises the following regions of continents:
In astronomy, declination is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the celestial equator, along the hour circle passing through the point in question.
A solstice is an event occurring when the Sun appears to reach 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 reference to the solstices and the equinoxes.
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 is currently 23°26′12.1″ (or 23.43669°) north of the Equator.
The Tropic of Capricorn is the circle of latitude that contains the subsolar point on the December solstice. It is thus the southernmost latitude where the Sun can be directly overhead. Its northern equivalent is the Tropic of Cancer.
A circle of latitude on Earth is an abstract east–west circle connecting all locations around Earth at a given latitude.
The Southern Hemisphere is the half of Earth that is south of the Equator. It contains all or parts of five continents, four oceans 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.
The midnight sun is a natural phenomenon that occurs in the summer months in places north of the Arctic Circle or south of the Antarctic Circle, when the Sun remains visible at the local midnight.
The thermal equator is a belt encircling the Earth, defined by the set of locations having the highest mean annual temperature at each longitude around the globe. Because local temperatures are sensitive to the geography of a region, mountain ranges and ocean currents ensure that smooth temperature gradients are impossible, the location of the thermal equator is not identical to that of the geographic Equator.
Twilight on Earth is the illumination of the lower atmosphere when the Sun itself is not directly visible because it is below the horizon. Twilight is produced by sunlight scattering in the upper atmosphere, illuminating the lower atmosphere so that Earth's surface is neither completely lit nor completely dark. The word twilight is also used to denote the periods of time when this illumination occurs.
A transit of Deimos across the Sun as seen from Mars occurs when Deimos passes directly between the Sun and a point on the surface of Mars, obscuring a small part of the Sun's disc for an observer on Mars. During a transit, Deimos can be seen from Mars as a small dark spot rapidly moving across the Sun's face.
Earth orbits the Sun at an average distance of 149.60 million km, and one complete orbit takes 365.256 days, during which time Earth has traveled 940 million km. Ignoring the influence of other solar system bodies, Earth's orbit is an ellipse with the Earth-Sun barycenter as one focus and a current eccentricity of 0.0167; since this value is close to zero, the center of the orbit is close, relative to the size of the orbit, to the center of the Sun.
In many cases astronomical phenomena viewed from the planet Mars are the same or similar to those seen from Earth but sometimes they can be quite different. For example, because the atmosphere of Mars does not contain an ozone layer, it is also possible to make UV observations from the surface of Mars.
The 30th parallel north is a circle of latitude that is 30 degrees north of the Earth's equatorial plane. It stands one-third of the way between the equator and the North Pole and crosses Africa, Asia, the Pacific Ocean, North America and the Atlantic Ocean.
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:
On Earth, daytime is roughly the period of the day during which any given point in the world experiences natural illumination from especially 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. During daytime, an observer sees indirect sunlight while in the shade, which includes cloud cover. 'Day' is sometimes used instead of 'daytime', in this case 'day' will mean 'the period of light between dawn and nightfall; the interval from sunrise to sunset', which is synonymous with daytime. However, in this context, in order to be clear "daytime" should be used distinguish it from "day" which typically refers to a 24-hour period.
The summer solstice, also known as midsummer, occurs when one of the Earth's poles has its maximum tilt toward the Sun. It happens twice yearly, once in each hemisphere. For that hemisphere, the summer solstice is when the Sun reaches its highest position in the sky and is the day with the longest period of daylight. Within the Arctic circle or Antarctic circle, there is continuous daylight around the summer solstice. On the summer solstice, Earth's maximum axial tilt toward the Sun is 23.44°. Likewise, the Sun's declination from the celestial equator is 23.44°.
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 of a rotating spheroid is the parallel at which latitude is defined to be 0°. It is the imaginary line on the spheroid, equidistant from its poles, dividing it into northern and southern hemispheres. In other words, it is the intersection of the spheroid with the plane perpendicular to its axis of rotation and midway between its geographical poles.
A season is a division of the year marked by changes in weather, ecology, and the amount of daylight. On Earth, seasons are the result of Earth's orbit around the Sun and Earth's axial tilt relative to the ecliptic plane. 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.
The Antarctic Circle is the most southerly of the five major circles of latitude that mark maps of the 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.