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 .
60-533: Winter is the coldest and darkest season of the year in polar and temperate climates . It occurs after autumn and before spring . The tilt of Earth's axis causes seasons; winter occurs when a hemisphere is 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
120-632: 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,
180-721: A location close to his capital city on the banks of the Euphrates . In the 7th century BC the Chinese had used icehouses to preserve vegetables and fruits. During the Tang dynastic rule in China (618–907 AD) a document refers to the practice of using ice that was in vogue during the Eastern Chou Dynasty (770–256 BC) by 94 workmen employed for "Ice-Service" to freeze everything from wine to dead bodies. Shachtman says that in
240-545: A magician to perform tricks such as producing thunder, lightning, lions, birds, trembling leaves and so forth. In 1620 he gave a demonstration in Westminster Abbey to the king and his courtiers on the power of cold. On a summer day, Shachtman says, Drebbel had created a chill (lowered the temperature by several degrees) in the hall of the Abbey, which made the king shiver and run out of the hall with his entourage. This
300-558: 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
360-434: A winter with a particular year, e.g. "Winter 2018". Solutions for this problem include naming both years, e.g. "Winter 18/19", or settling on the year the season starts in or on the year most of its days belong to, which is the later year for most definitions. Ecological reckoning of winter differs from calendar-based by avoiding the use of fixed dates. It is one of six seasons recognized by most ecologists who customarily use
420-533: Is summer in the Southern Hemisphere , and vice versa. Winter typically brings precipitation that, depending on a region's climate , is mainly rain or snow . 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
480-547: Is 1 or 2 February. In Chinese astronomy and other East Asian calendars , winter is taken to commence on or around 7 November, on Lìdōng , and end with the arrival of spring on 3 or 4 February, on Lìchūn . Late Roman Republic scholar Marcus Terentius Varro defined winter as lasting from the fourth day before the Ides of November (10 November) to the eighth day before the Ides of Februarius (6 February). This system of seasons
540-418: Is based on the length of days exclusively. The three-month period of the shortest days and weakest solar radiation occurs during November, December and January in the Northern Hemisphere and May, June and July in the Southern Hemisphere . Many mainland European countries tended to recognize Martinmas or St. Martin's Day (11 November) as the first calendar day of winter. The day falls at the midpoint between
600-533: Is earlier than the solstice delimited definition, but later than the daylight (Celtic or Chinese) definition. Depending on seasonal lag , this period will vary between climatic regions. Since by almost all definitions valid for the Northern Hemisphere, winter spans 31 December and 1 January, the season is split across years, just like summer in the Southern Hemisphere. Each calendar year includes parts of two winters. This causes ambiguity in associating
660-640: Is often a subjective perception . A lower bound to temperature is absolute zero , defined as 0.00 K on the Kelvin scale, an absolute thermodynamic temperature scale. This corresponds to −273.15 °C on the Celsius scale , −459.67 °F on the Fahrenheit scale , and 0.00 °R on the Rankine scale . Since temperature relates to the thermal energy held by an object or a sample of matter, which
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#1732772687004720-518: Is often defined by meteorologists to be the three calendar months with the lowest average temperatures. This corresponds to the months of December, January and February in the Northern Hemisphere , and June, July and August in the Southern Hemisphere . The coldest average temperatures of the season are typically experienced in January or February in the Northern Hemisphere and in June, July or August in
780-466: Is referred to as the eve of the birth of Mithra , who symbolised light, goodness and strength on Earth. In Greek mythology , Hades kidnapped Persephone to be his wife. Zeus ordered Hades to return her to Demeter , the goddess of the Earth and her mother. Hades tricked Persephone into eating the food of the dead, so Zeus decreed that she spend six months with Demeter and six months with Hades. During
840-428: Is the kinetic energy of the random motion of the particle constituents of matter, an object will have less thermal energy when it is colder and more when it is hotter. If it were possible to cool a system to absolute zero, all motion of the particles in a sample of matter would cease and they would be at complete rest in the classical sense. The object could be described as having zero thermal energy. Microscopically in
900-406: Is the process of cooling an object by exposing it to air . This will only work if the air is at a lower temperature than the object, and the process can be enhanced by increasing the surface area , increasing the coolant flow rate, or decreasing the mass of the object. Another common method of cooling is exposing an object to ice , dry ice , or liquid nitrogen . This works by conduction ;
960-483: The Great Plains (a long way from the ocean), has a January high of −11.3 °C (11.7 °F) and a low of −21.4 °C (−6.5 °F). In comparison, Vancouver , on the west coast (with a marine influence from moderating Pacific winds), has a January low of 1.4 °C (34.5 °F), with days well above freezing, at 6.9 °C (44.4 °F). Both places are at 49°N latitude and in the same western half of
1020-516: The March equinox . These dates are somewhat later than those used to define the beginning and end of the meteorological winter — usually considered to span the entirety of December, January, and February in the Northern Hemisphere and June, July, and August in the Southern. Astronomically, the winter solstice — being the day of the year that has fewest hours of daylight — ought to be in the middle of
1080-465: 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
1140-567: The Proto-Germanic noun *wintru- , whose origin is unclear. Several proposals exist, a commonly mentioned one connecting it to the Proto-Indo-European root *wed- 'water' or a nasal infix variant *wend- . The tilt of the Earth's axis relative to its orbital plane plays a large role in the formation of weather. The Earth is tilted at an angle of 23.44° to the plane of its orbit, causing different latitudes to directly face
1200-483: 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
1260-583: 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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#17327726870041320-421: The 17th century. The intellectual barrier was broken by Francis Bacon and Robert Boyle who followed him in this quest for knowledge of cold. Boyle did extensive experimentation during the 17th century in the discipline of cold, and his research on pressure and volume was the forerunner of research in the field of cold during the 19th century. He explained his approach as "Bacon's identification of heat and cold as
1380-441: The 1920s expanded the refrigerator market during the 1930s. Home freezers as separate compartments (larger than necessary just for ice cubes) were introduced in 1940. Frozen foods, previously a luxury item, became commonplace. Cold has numerous physiological and pathological effects on the human body , as well as on other organisms. Cold environments may promote certain psychological traits, as well as having direct effects on
1440-513: The 4th century AD, the brother of the Japanese emperor Nintoku gave him a gift of ice from a mountain. The Emperor was so happy with the gift that he named the first of June as the "Day of Ice" and ceremoniously gave blocks of ice to his officials. Even in ancient times, Shachtman says, in Egypt and India, night cooling by evaporation of water and heat radiation, and the ability of salts to lower
1500-451: The Earth, the winter Sun has a lower maximum altitude in the sky than the summer Sun. During winter in either hemisphere, the lower altitude of the Sun causes the sunlight to hit the Earth at an oblique angle. Thus a lower amount of solar radiation strikes the Earth per unit of surface area. Furthermore, the light must travel a longer distance through the atmosphere, allowing the atmosphere to dissipate more heat. Compared with these effects,
1560-611: The Northern Hemisphere, due to the large land masses there. In the Southern Hemisphere, the more maritime climate and the relative lack of land south of 40°S make the winters milder; thus, snow and ice are less common in inhabited regions of the Southern Hemisphere. In this region, snow occurs every year in elevated regions such as the Andes, the Great Dividing Range in Australia, and the mountains of New Zealand, and also in
1620-686: The Southern Hemisphere. Nighttime predominates in the winter season, and in some regions, winter has the highest rate of precipitation as well as prolonged dampness because of permanent snow cover or high precipitation rates coupled with low temperatures, precluding evaporation. Blizzards often develop and cause many transportation delays. Diamond dust , also known as ice needles or ice crystals, forms at temperatures approaching −40 °C (−40 °F) due to air with slightly higher moisture from above mixing with colder, surface-based air. They are made of simple hexagonal ice crystals. The Swedish Meteorological Institute (SMHI) defines thermal winter as when
1680-403: The Sun as the Earth moves through its orbit. This variation brings about seasons. When it is winter in the Northern Hemisphere, the Southern Hemisphere faces the Sun more directly and thus experiences warmer temperatures than the Northern Hemisphere. Conversely, winter in the Southern Hemisphere occurs when the Northern Hemisphere is tilted more toward the Sun. From the perspective of an observer on
1740-663: 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
1800-451: The ability to move. Shivering is one of the first physiological responses to cold. Even at low temperatures, the cold can massively disrupt blood circulation. Extracellular water freezes and tissue is destroyed. It affects fingers, toes, nose, ears and cheeks particularly often. They discolor, swell, blister, and bleed. The so-called frostnip leads to local frostbite or even to the death of entire body parts. Only temporary cold reactions of
1860-401: The body's ability to maintain both core and surface heat of the body. Slipping on icy surfaces is a common cause of winter injuries. Other injuries from the cold include: Rates of influenza , COVID-19 , and other respiratory diseases also increase during the winter. In Persian culture , the winter solstice is called Yaldā (meaning: birth) and has been celebrated for thousands of years. It
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1920-403: The cold of the latter, the nitre by adding to its own cold, but the salt by supplying activity to the cold snow." This explanation on the cold inducing aspects of nitre and salt was tried then by many scientists. Shachtman says it was the lack of scientific knowledge in physics and chemistry that had held back progress in the beneficial use of ice until a drastic change in religious opinions in
1980-555: The continent. A similar but less extreme effect is found in Europe: in spite of their northerly latitude, the British Isles lack non-mountain weather stations with a below-freezing mean January temperature. Meteorological reckoning is the method of measuring the winter season used by meteorologists based on "sensible weather patterns" for record keeping purposes, so the start of meteorological winter varies with latitude. Winter
2040-648: The daily mean temperatures are below 0 °C (32 °F) for five consecutive days. According to the SMHI, winter in Scandinavia is more pronounced when Atlantic low-pressure systems take more southerly and northerly routes, leaving the path open for high-pressure systems to come in and cold temperatures to occur. As a result, the coldest January on record in Stockholm , in 1987, was also the sunniest. Accumulations of snow and ice are commonly associated with winter in
2100-470: The description of quantum mechanics , however, matter still has zero-point energy even at absolute zero, because of the uncertainty principle . Cooling refers to the process of becoming cold, or lowering in temperature . This could be accomplished by removing heat from a system, or exposing the system to an environment with a lower temperature. Coolants are fluids used to cool objects, prevent freezing and prevent erosion in machines. Air cooling
2160-464: The effect of the changes in the distance of the Earth from the Sun (due to the Earth's elliptical orbit) is negligible. The manifestation of the meteorological winter (freezing temperatures) in the northerly snow-prone latitudes is highly variable, depending on elevation, position versus marine winds, and the amount of precipitation. For instance, within Canada (a country of cold winters), Winnipeg , on
2220-652: 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
2280-425: The freezing temperature of water was practiced. The ancient people of Rome and Greece were aware that boiled water cooled quicker than the ordinary water; the reason for this is that with boiling of water carbon dioxide and other gases, which are deterrents to cooling, are removed; but this fact was not known till the 17th century. Shachtman says that King James VI and I supported the work of Cornelis Drebbel as
2340-645: The heat is transferred from the relatively warm object to the relatively cold coolant. Laser cooling and magnetic evaporative cooling are techniques used to reach very low temperatures. In ancient times, ice was not adopted for food preservation but used to cool wine which the Romans had also done. According to Pliny , Emperor Nero invented the ice bucket to chill wines instead of adding it to wine to make it cold as it would dilute it. Some time around 1700 BC Zimri-Lim , king of Mari Kingdom in northwest Iraq had created an "icehouse" called bit shurpin at
2400-412: The identically named common cold . No scientific evidence of this has been found, although the disease, alongside influenza and others, does increase in prevalence with colder weather. Bibliography Northern Hemisphere Due to Earth's axial tilt of 23.439281°, there is a seasonal variation in the lengths of the day and night. There is also a seasonal variation in temperatures, which lags
2460-458: The insulating effects of snow by being buried in it. Larger plants, particularly deciduous trees , usually let their upper part go dormant, but their roots are still protected by the snow layer. Few plants bloom in the winter, one exception being the flowering plum , which flowers in time for Chinese New Year . The process by which plants become acclimated to cold weather is called hardening . Humans are sensitive to winter cold, which compromises
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2520-522: The last day of February. In many countries in the Southern Hemisphere , including Australia , New Zealand , and South Africa , winter begins on 1 June and ends on 31 August. In Celtic nations such as Ireland (using the Irish calendar ) and in Scandinavia, the winter solstice is traditionally considered as midwinter, with the winter season beginning 1 November, on All Hallows , or Samhain . Winter ends and spring begins on Imbolc , or Candlemas , which
2580-410: The mid-19th century to the 1930s, when the refrigerator was introduced into the home. Most municipally consumed ice was harvested in winter from snow-packed areas or frozen lakes, stored in ice houses , and delivered domestically as iceboxes became more common. In 1913, refrigerators for home use were invented. In 1923 Frigidaire introduced the first self-contained unit. The introduction of Freon in
2640-419: The old Julian equinox and solstice dates. Also, Valentine's Day (14 February) is recognized by some countries as heralding the first rites of spring, such as flowers blooming. The three-month period associated with the coldest average temperatures typically begins somewhere in late November or early December in the Northern Hemisphere and lasts through late February or early March. This "thermological winter"
2700-413: The prevernal season as early as late January in mild temperate climates. To survive the harshness of winter, many animals have developed different behavioral and morphological adaptations for overwintering : Some annual plants never survive the winter. Other annual plants require winter cold to complete their life cycle; this is known as vernalization . As for perennials , many small ones profit from
2760-477: The right and left hands of nature". Boyle also refuted some of the theories mooted by Aristotle on cold by experimenting on transmission of cold from one material to the other. He proved that water was not the only source of cold but gold, silver and crystal, which had no water content, could also change to severe cold condition. In the United States from about 1850 till end of 19th century export of ice
2820-468: 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 the Northern Hemisphere, together with about two-thirds of Africa and
2880-424: The season, but seasonal lag means that the coldest period normally follows the solstice by a few weeks. In some cultures, the season is regarded as beginning at the solstice and ending on the following equinox . In the Northern Hemisphere, depending on the year, this corresponds to the period between 20, 21 or 22 December and 19, 20 or 21 March. In an old Norwegian tradition, winter begins on 14 October and ends on
2940-482: 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 and depend on latitude. They differ 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 ). The English word winter comes from
3000-493: The skin are without consequences. As blood vessels contract, they become cool and pale, with less oxygen getting into the tissue. Warmth stimulates blood circulation again and is painful but harmless. Comprehensive protection against the cold is particularly important for children and for sports. Extreme cold temperatures may lead to frostbite , sepsis , and hypothermia , which in turn may result in death. A common, but false, statement states that cold weather itself can induce
3060-512: The southerly Patagonia region of South Argentina. Snow occurs year-round in Antarctica . In the Northern Hemisphere , some authorities define the period of winter based on astronomical fixed points (i.e., based solely on the position of the Earth in its orbit around the Sun), regardless of weather conditions. In one version of this definition, winter begins at the winter solstice and ends at
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#17327726870043120-411: The term hibernal for this period of the year (the other ecological seasons being prevernal, vernal, estival, serotinal, and autumnal). The hibernal season coincides with the main period of biological dormancy each year whose dates vary according to local and regional climates in temperate zones of the Earth. The appearance of flowering plants like the crocus can mark the change from ecological winter to
3180-420: The time her daughter is with Hades, Demeter became depressed and caused winter. In Welsh mythology , Gwyn ap Nudd abducted a maiden named Creiddylad . On May Day, her lover, Gwythr ap Greidawl , fought Gwyn to win her back. The battle between them represented the contest between summer and winter. Cold Cold is the presence of low temperature , especially in the atmosphere. In common usage, cold
3240-561: 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 the September equinox (typically on 23 September UTC). The dates vary each year due to the difference between
3300-448: 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
3360-489: 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
3420-461: Was an incredible spectacle, says Shachtman. Several years before, Giambattista della Porta had demonstrated at the Abbey "ice fantasy gardens, intricate ice sculptures" and also iced drinks for banquets in Florence . The only reference to the artificial freezing created by Drebbel was by Francis Bacon . His demonstration was not taken seriously as it was considered one of his magic tricks, as there
3480-450: Was filled with ice. In 1825, ice harvesting by use of a horse drawn ice cutting device was invented by Nathaniel J. Wyeth. The cut blocks of uniform size ice was a cheap method of food preservation widely practiced in the United States. Also developed in 1855 was a steam powered device to haul 600 tons of ice per hour. More innovations ensued. Devices using compressed air as a refrigerants were invented. Iceboxes were in widespread use from
3540-507: Was no practical application then. Drebbel had not revealed his secrets. Shachtman says that Lord Chancellor Bacon, an advocate of experimental science, had tried in Novum Organum , published in the late 1620s, to explain the artificial freezing experiment at Westminster Abbey, though he was not present during the demonstration, as " Nitre (or rather its spirit) is very cold, and hence nitre or salt when added to snow or ice intensifies
3600-409: Was second only to cotton. The first ice box was developed by Thomas Moore, a farmer from Maryland in 1810 to carry butter in an oval shaped wooden tub. The tub was provided with a metal lining in its interior and surrounded by a packing of ice. A rabbit skin was used as insulation. Moore also developed an ice box for domestic use with the container built over a space of 6 cubic feet (0.17 m ) which
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