WINTER

Winter is one of the four seasons of temperate zones. Calculated astronomically, the winter solstice ought to be the middle of winter, but temperature lag means that most cultures consider mid-winter to be several weeks later, with some believing that winter begins on the solstice and ends on the equinox. From a meteorological perspective, winter is the season with the shortest days and the lowest average temperatures. It has colder weather and, especially in the higher latitudes or altitudes, snow and ice. The coldest average temperatures of the season are typically experienced in January in the Northern Hemisphere and in July in the Southern Hemisphere.

Aspects
In many parts of the world, winter is associated with snow and ice.
Above, winter in Germany.

Meteorology
Animation of snow cover changing with the seasons.

Meteorological winter is the season having the shortest days and the lowest temperatures. Nighttime predominates the winter season, and in some regions it 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. A rare meteorological phenomenon encountered during winter is ice fog, which comprises ice crystals suspended in the air; it occurs only at very low temperatures, below about −30°C (−22°F)[1].

Accumulations of snow and ice are mostly associated with winter in 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 makes 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 occurs in the southerly Patagonia region of South America. Snow occurs year-round in Antarctica.

Period
The road from Dornbirn, Austria to the mountain village of Ebnit in winter.

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 November 1, on All Hallows, or Samhain. Winter ends and spring begins on Imbolc, or Candlemas, which is February 1 or February 2. This system of seasons 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 through July in the Southern Hemisphere.)

Also, many mainland European countries tend to recognize Martinmas, St. Martin's day (November 11), as the first calendar day of winter. The day falls at midpoint between the old Julian equinox and solstice dates. Also, Valentine's Day (February 14) is recognized by some countries as heralding the first rites of spring, such as flowers blooming.

In Chinese astronomy and other East Asian calendars, winter is taken to commence on or around November 7, with the Jiéqì (known as 立冬 lì dōng—literally, "establishment of winter").

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" is earlier than the solstice definition but later than the daylight (Celtic) definition. Depending on seasonal lag, this period will vary among climatic regions.

Cultural influences such as Christmas creep may have led to the winter season being perceived as beginning earlier in recent years.

Causes
See also: Effect of sun angle on climate

The tilt of the Earth's axis relative to its orbital plane has a dramatic effect on the weather. The Earth is tilted at an angle of 23.44° to the plane of its orbit, and this causes different latitudes on the Earth to directly face the Sun as the Earth moves through its orbit. It is this variation that primarily brings about the 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 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 in winter causes the sunlight to hit that hemisphere at an oblique angle. In regions experiencing winter, the same amount of solar radiation is spread out over a larger area. This effect is compounded by the larger distance that the light must travel through the atmosphere, allowing the atmosphere to dissipate more heat. Compared with these effects, the changes in the distance of the earth from the sun are negligible.

Exceptional cases

* 1684, when the Thames, hosting one of many River Thames frost fairs, and the sea froze up to two miles out around the coast.
* Year Without a Summer was the name for 1816, because the weather was so cold that it reminded people of winter all year.
* In Europe, the winters of 1947,[1] 1962–63, and 1981–82 were considered abnormally cold.

Ecology
The snowshoe hare is one animal that changes color in winter.

To survive the harshness of winter, many animals have developed different behavioral and morphological adaptations for overwintering:

* Migration is a common effect of winter upon animals, notably birds. However, the majority of birds do not migrate—the cardinal and European Robin, for example. Some butterflies also migrate seasonally.
* Hibernation is a state of reduced metabolic activity during the winter. Some animals "sleep" during winter and only come out when the warm weather returns; e.g., gophers, frogs, snakes, and bats.
* Some animals store food for the winter and live on it instead of hibernating completely. This is the case for squirrels, beavers, skunks, badgers, and raccoons.
* Resistance is observed when an animal endures winter but changes in ways such as color and musculature. The color of the fur or plumage changes to white (in order to be confused with snow) and thus retains its cryptic coloration year-round. Examples are the ptarmigan, arctic fox, weasel, white-tailed jackrabbit, and mountain hare.
* Some fur-coated mammals grow a heavier coat during the winter; this improves the heat-retention qualities of the fur. The coat is then shed following the winter season to allow better cooling. The heavier coat in winter made it a favorite season for trappers, who sought more profitable skins.
* Snow also affects the ways animals behave; many take advantage of the insulating properties of snow by burrowing in it. Mice and voles typically live under the snow layer.

Annual plants never survive the winter. As for perennials, many small ones profit from 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.

Activities
Snowboarder in the halfpipe.
Main article: Winter sport

Snow activities

Many winter activities involve the use of snow in some form (which sometimes is man-made, using snow cannons):

* Bobsledding — a winter sport in which teams make timed runs down narrow, twisting, banked, purpose-built ice-covered tracks in a steerable sled.
* Skiing — the activity of gliding over snow using fiberglass planks called skis that are strapped to the skiers' feet with ski bindings.
* Sledding — a gravity-powered activity using a sled to glide downhill.
* Snow castle building — for example, constructions such as the SnowCastle of Kemi, the largest in the world.
* Snowball fight — a physical game in which snowballs are thrown with the intention of hitting someone else.
* Snowboarding — an increasingly common sport in which participants strap a composite board to their feet and slide down a snow-covered mountain.
* Snowman building — creating a manlike model out of snow.
* Snowmobiling — driving snowmobiles in snow, across frozen lakes, on public trails, or around mountains.
* Snowshoeing — a means of travel on top of the snow by increasing the surface area of the feet by wearing snowshoes.

Ice activities
Bandy, an early form of ice hockey.

Many other winter activities and sports focus on ice, which may be contained in an ice rink.

* Curling — a team sport using brooms and stones. The object of the game is to slide your stones in a bullseye and get your opponent's stones out of it.
* Ice biking — the continuation of regular cycling activities in the winter and cold weather.
* Ice boating — a means of travel in a specialized boat similar in appearance to a sailboat but fitted with skis or runners (skates) and designed to run over ice instead of (liquid) water.
* Ice climbing — the recreational activity of climbing ice formations such as icefalls and frozen waterfalls.
* Ice diving — a type of penetration diving where the dive takes place under ice.
* Ice fishing — the sport of catching fish with lines and hooks through an opening in the ice on a frozen body of water.
* Ice hockey — a team sport played on the ice with skates, sticks, and a puck. The goal is to send the puck into the opposing team's net.
* Ice racing — automobile racing on ice surfaces.
* Ice sculpture — elaborate sculptures are carved out of blocks of ice.
* Ice skating — a means of traveling on ice with skates, narrow (and sometimes parabolic) bladelike devices molded into special boots.

Psychology
This section does not cite any references or sources. Please help improve this article by adding citations to reliable sources (ideally, using inline citations). Unsourced material may be challenged and removed. (December 2008)
Long, harsh winters are believed to have affected the Russian national character.

Passing seasons change the habits and moods of people. During the winter months in the Northern Hemisphere, a gloominess (nicknamed "winter blues," "February blahs," or "holiday depression") or doldrums is informally noted amongst people. The severest cases of this type of depression are diagnosed as seasonal affective disorder (SAD). Symptoms include excess sleeping, tiredness, depression, and physical aches. Although causes include genetic disposition and stress, the prevailing environmental influence is decreased exposure to light because of the angle of the sun and cloud cover.

Symbolism

Some use winter to suggest death, as in Robert Frost's "Stopping by Woods on a Snowy Evening." Some use it to suggest the absence of hope, as in C.S. Lewis' The Lion, the Witch and the Wardrobe, where it was always winter but never Christmas. Winter is one concerto in Antonio Vivaldi's "The Four Seasons," and there are many examples of four paintings all showing the same scene in different seasons. Ursula K. LeGuin's novel The Left Hand of Darkness is set on a planet named Winter. In Alex Raymond's comic strip Flash Gordon, there is a land called Frigia, where it is always winter. The land of Frigia is also featured in the serial Flash Gordon Conquers the Universe. Other uses of winter in the graphic arts occur in Winsor McCay's Little Nemo in Slumberland. There are many films in which a winter setting plays an important role, Fargo being an example. Novels such as Ethan Frome also use a winter setting to mirror the bleak, frozen feelings that the characters harbor. The film Requiem for a Dream concludes with "Act III: Winter," in which the movie reaches its chilling climax.

Mythology

In various cultures

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. However, Hades tricked Persephone into eating the food of the dead, so Zeus decreed that Persephone would spend six months with Demeter and six months with Hades. During 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.