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29-732: It is on average the warmest month in most of the Northern Hemisphere , where it is the second month of summer, and the coldest month in much of the Southern Hemisphere , where it is the second month of winter. The second half of the year commences in July. In the Southern Hemisphere, July is the seasonal equivalent of January in the Northern hemisphere. " Dog days " are considered to begin in early July in

58-632: A counterclockwise pattern. Hurricanes and tropical storms (massive low-pressure systems) spin counterclockwise in the Northern Hemisphere. 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,

87-568: Is a seasonal variation in the lengths of the day and night. There is also a seasonal variation in temperatures, which lags the variation in day and night. Conventionally, winter in the Northern Hemisphere is taken as the period from the December solstice (typically December 21 UTC ) to the March equinox (typically March 20 UTC), while summer is taken as the period from the June solstice through to

116-789: Is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the Phanerozoic eon. It follows the Neogene Period and spans from 2.58 million years ago to the present. The Quaternary Period is divided into two epochs: the Pleistocene (2.58 million years ago to 11.7 thousand years ago) and

145-500: 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. 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 continents of North America and mainland Eurasia are located entirely in

174-716: The Gelasian Stage, which was formerly considered part of the Neogene Period and Pliocene Epoch. This was later revised to 2.58 mya. The Anthropocene was proposed as a third epoch as a mark of the anthropogenic impact on the global environment starting with the Industrial Revolution , or about 200 years ago. The Anthropocene was rejected as a geological epoch in 2024 by the International Union of Geological Sciences (IUGS),

203-718: The Holocene (11.7 thousand years ago to today); a proposed third epoch, the Anthropocene , was rejected in 2024 by IUGS , the governing body of the ICS. The Quaternary is typically defined by the Quaternary glaciation , the cyclic growth and decay of continental ice sheets related to the Milankovitch cycles and the associated climate and environmental changes that they caused. In 1759 Giovanni Arduino proposed that

232-515: The Northern Hemisphere , when the hot sultry weather of summer usually starts. Spring lambs born in late winter or early spring are usually sold before 1 July. July's birthstone is the ruby , which symbolizes contentment. Its birth flowers are the larkspur and the water lily . The zodiac signs are Cancer (until July 22) and Leo (July 23 onward). This list does not necessarily imply either official status nor general observance. (All Baha'i, Islamic, and Jewish observances begin at

261-465: 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

290-547: 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

319-528: The last glacial period ended about 10,000 years ago. Earth is currently in an interglacial period of the Quaternary , called the Holocene . 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

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348-611: 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. 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. Quaternary The Quaternary ( / k w ə ˈ t ɜːr n ə r i , ˈ k w ɒ t ər n ɛr i / kwə- TUR -nə-ree, KWOT -ər-nerr-ee )

377-571: The Northern Hemisphere, together with about two-thirds of Africa and a small part of South 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

406-552: The Pleistocene includes a portion of what was, prior to 2009, defined as the Pliocene . Quaternary stratigraphers usually worked with regional subdivisions. From the 1970s, the International Commission on Stratigraphy (ICS) tried to make a single geologic time scale based on GSSP 's, which could be used internationally. The Quaternary subdivisions were defined based on biostratigraphy instead of paleoclimate . This led to

435-606: The Sun can be seen to the north, directly overhead, or to the south at noon, depending 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. The North Pole faces away from the Galactic Center of the Milky Way . This results in the Milky Way being sparser and dimmer in

464-644: The emergence of the straits of Bosphorus and Skagerrak during glacial epochs, which respectively turned the Black Sea and Baltic Sea into fresh water lakes, followed by their flooding (and return to salt water) by rising sea level; the periodic filling of the English Channel , forming a land bridge between Britain and the European mainland; the periodic closing of the Bering Strait , forming

493-728: The establishment of the Glacial Theory. In time, thanks to the refinement of geology, it has been demonstrated that there were several periods of glacial advance and retreat and that past temperatures on Earth were very different from today. In particular, the Milankovitch cycles of Milutin Milankovitch are based on the premise that variations in incoming solar radiation are a fundamental factor controlling Earth's climate. During this time, substantial glaciers advanced and retreated over much of North America and Europe, parts of South America and Asia, and all of Antarctica. There

522-652: 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

551-418: The geological strata of northern Italy could be divided into four successive formations or "orders" ( Italian : quattro ordini ). The term "quaternary" was introduced by Jules Desnoyers in 1829 for sediments of France 's Seine Basin that clearly seemed to be younger than Tertiary Period rocks . The Quaternary Period follows the Neogene Period and extends to the present. The Quaternary covers

580-450: The governing body of the ICS. The 2.58 million years of the Quaternary represents the time during which recognisable humans existed. Over this geologically short time period there has been relatively little change in the distribution of the continents due to plate tectonics . The Quaternary geological record is preserved in greater detail than that for earlier periods. The major geographical changes during this time period included

609-596: The land bridge between Asia and North America ; and the periodic flash flooding of Scablands of the American Northwest by glacial water. The current extent of Hudson Bay , the Great Lakes and other major lakes of North America are a consequence of the Canadian Shield 's readjustment since the last ice age; different shorelines have existed over the course of Quaternary time. The climate

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638-481: The presence of traces of the passage of a glacier at a considerable distance from the Alps. This idea was initially disputed by another Swiss scientist, Louis Agassiz , but when he undertook to disprove it, he ended up affirming his colleague's hypothesis. A year later, Agassiz raised the hypothesis of a great glacial period that would have had long-reaching general effects. This idea gained him international fame and led to

667-523: The problem that the proposed base of the Pleistocene was at 1.805 million years ago, long after the start of the major glaciations of the northern hemisphere. The ICS then proposed to abolish use of the name Quaternary altogether, which appeared unacceptable to the International Union for Quaternary Research (INQUA). In 2009, it was decided to make the Quaternary the youngest period of the Cenozoic Era with its base at 2.588 mya and including

696-628: The sundown before the date listed, and end at sundown of the date in question unless otherwise noted.) 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 . Due to Earth's axial tilt of 23.439281°, there

725-399: The time span of glaciations classified as the Pleistocene , and includes the present interglacial time-period, the Holocene . This places the start of the Quaternary at the onset of Northern Hemisphere glaciation approximately 2.6 million years ago ( mya ). Prior to 2009, the Pleistocene was defined to be from 1.805 million years ago to the present, so the current definition of

754-448: The weather patterns that affect many factors within the north coast. 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

783-489: 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. Within the Northern Hemisphere, oceanic currents can change

812-580: Was a major extinction of large mammals globally during the Late Pleistocene Epoch. Many forms such as sabre-toothed cats , mammoths , mastodons , glyptodonts , etc., became extinct worldwide. Others, including horses , camels and American cheetahs became extinct in North America . The Great Lakes formed and giant mammals thrived in parts of North America and Eurasia not covered in ice. These mammals became extinct when

841-464: Was one of periodic glaciations with continental glaciers moving as far from the poles as 40 degrees latitude . Glaciation took place repeatedly during the Quaternary Ice age  – a term coined by Schimper in 1839 that began with the start of the Quaternary about 2.58 Mya and continues to the present day. In 1821, a Swiss engineer, Ignaz Venetz , presented an article in which he suggested

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