question: The difference in seasons in northern and southern hemispheres
comment: Seasons are the result of the tilt of the Earth. Earth spins on a slight angle compared to the circle of its orbit around the Sun. This means that at different times of year, the poles are pointed towards or away from the Sun. This affects how much daylight the poles get, with the impact decreasing as you get towards the equator. In the Winter time, the pole is pointed away from the sun, so days are shorter, there is less sunlight and the weather gets colder. In the Summer time, the pole is pointed toward the sun, so days are longer, there is more sunlight and temperatures rise. When the North Pole is pointed towards the sun, it means the South Pole must be pointed away from the sun and vice versa.
passages: The seasonal cycle in the polar and temperate zones of one hemisphere is opposite to that of the other. When it is summer in the Northern Hemisphere, it is winter in the Southern, and vice versa.
  
  Section::::Causes and effects.:Tropics.
   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.
  
  Section::::Geography and climate.
   Orbital eccentricity can influence temperatures, but on Earth, this effect is small and is more than counteracted by other factors; research shows that the Earth as a whole is actually slightly warmer when "farther" from the sun. This is because the Northern Hemisphere has more land than the Southern, and land warms more readily than sea.
  
  Any noticeable intensification of southern winters and summers due to Earth's elliptical orbit is mitigated by the abundance of water in the Southern Hemisphere.
  
  Section::::Causes and effects.:Maritime and hemispheric.
   Section::::Four-season calendar reckoning.:Astronomical.
  
  Astronomical timing as the basis for designating the temperate seasons dates back at least to the Julian calendar used by the ancient Romans. It continues to be used on many modern Gregorian calendars worldwide, although some countries like Australia, New Zealand, Pakistan and Russia prefer to use meteorological reckoning. The precise timing of the seasons is determined by the exact times of transit of the sun over the tropics of Cancer and Capricorn for the solstices and the times of the sun's transit over the equator for the equinoxes, or a traditional date close to these times.
   While phenology fairly consistently points to an earlier spring across temperate regions of North America, a recent comprehensive study of the subarctic showed greater variability in the timing of green-up, with some areas advancing, and some having no discernible trend over a recent 44-year period.
  
  Another 40 year phenological study in China found greater warming over that period in the more northerly sites studied, with sites experiencing cooling mostly in the south, indicating that the temperature variation with latitude is decreasing there.
   Six ecological seasons can be distinguished which do not have fixed calendar-based dates like the meteorological and astronomical seasons. Oceanic regions tend to experience the beginning of the hibernal season up to a month later than . Conversely, prevernal and vernal seasons begin up to a month earlier near oceanic and coastal areas. For example, prevernal crocus blooms typically appear as early as February in coastal areas of British Columbia, the British Isles, but generally don't appear until March or April in locations like the Midwest USA or parts of eastern Europe. The actual dates for each season vary by climate region and can shift from one year to the next. Average dates listed here are for mild and cool temperate climate zones in the Northern Hemisphere:
   In recent decades, season creep has been observed, which means that many phenological signs of spring are occurring earlier in many regions by around two days per decade.
  
  Spring in the Southern Hemisphere is different in several significant ways to that of the Northern Hemisphere for several reasons, including:
  
  BULLET::::1. There is no land bridge between Southern Hemisphere countries and the Antarctic zone capable of bringing in cold air without the temperature-mitigating effects of extensive tracts of water;
  
  BULLET::::2. The vastly greater amount of ocean in the Southern Hemisphere at most latitudes;
   Section::::Non-calendar-based reckoning.:Indigenous ecological.
   In the temperate and polar regions, seasons are marked by changes in the amount of sunlight, which in turn often causes cycles of dormancy in plants and hibernation in animals. These effects vary with latitude and with proximity to bodies of water. For example, the South Pole is in the middle of the continent of Antarctica and therefore a considerable distance from the moderating influence of the southern oceans. The North Pole is in the Arctic Ocean, and thus its temperature extremes are buffered by the water. The result is that the South Pole is consistently colder during the southern winter than the North Pole during the northern winter.
   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.
   Therefore, for temperate areas in the northern hemisphere, spring begins on 1 March, summer on 1 June, autumn on 1 September, and winter on 1 December. For the southern hemisphere temperate zone, spring begins on 1 September, summer on 1 December, autumn on 1 March, and winter on 1 June. In Australasia the meteorological terms for seasons apply to the temperate zone that occupies all of New Zealand, New South Wales, Victoria, Tasmania, the south-eastern corner of South Australia and the south-west of Western Australia, and the south east Queensland areas south of Brisbane.
   Regardless of the time of year, the northern and southern hemispheres always experience opposite seasons. This is because during summer or winter, one part of the planet is more directly exposed to the rays of the Sun (see "Fig. 1") than the other, and this exposure alternates as the Earth revolves in its orbit. For approximately half of the year (from around March 20 to around September 22), the Northern Hemisphere tips toward the Sun, with the maximum amount occurring on about June 21. For the other half of the year, the same happens, but in the Southern Hemisphere instead of the Northern, with the maximum around December 21. The two instants when the Sun is directly overhead at the Equator are the equinoxes. Also at that moment, both the North Pole and the South Pole of the Earth are just on the terminator, and hence day and night are equally divided between the two hemispheres. Around the March equinox, the Northern Hemisphere will be experiencing spring as the hours of daylight increase, and the Southern Hemisphere is experiencing autumn as daylight hours shorten.
   Calendar-based reckoning defines the seasons in absolute rather than relative terms. Accordingly, if floral activity is regularly observed during the coolest quarter of the year in a particular area, it is still considered winter despite the traditional association of flowers with spring and summer. Additionally, the seasons are considered to change on the same dates everywhere that uses a particular calendar method regardless of variations in climate from one area to another. Most calendar-based methods use a four-season model to identify the warmest and coldest seasons, which are separated by two intermediate seasons.
  
  Section::::Four-season calendar reckoning.:Meteorological.
   Floral and animal activity variation near the equator depends more on wet/dry cycles than seasonal temperature variations, with different species flowering (or emerging from cocoons) at specific times before, during, or after the monsoon season. Thus, the tropics are characterized by numerous "mini-seasons" within the larger seasonal blocks of time.
  
  In the tropical parts of Australia in the northern parts of Queensland, Western Australia and the Northern Territory, wet and dry seasons are observed in addition to or in place of temperate season names.
  
  Section::::Non-calendar-based reckoning.:Polar.
   Seasonal weather fluctuations (changes) also depend on factors such as proximity to oceans or other large bodies of water, currents in those oceans, El Niño/ENSO and other oceanic cycles, and prevailing winds.
   The Bengali Calendar is similar but differs in start and end times. It has the following seasons or ritu:
  
  The Tamil calendar follows a similar pattern of six seasons
  
  Section::::"Official" seasons.
   In the tropics, where seasonal dates also vary, it is more common to speak of the rainy (or wet, or monsoon) season versus the dry season. For example, in Nicaragua the dry season (November to April) is called 'summer' and the rainy season (May to October) is called 'winter', even though it is located in the northern hemisphere. In some tropical areas a three-way division into hot, rainy, and cool season is used. There is no noticeable change in the amount of sunlight at different times of the year. However, many regions (such as the northern Indian ocean) are subject to monsoon rain and wind cycles.
   By astronomical convention, the four seasons can be determined by the solstices—the points in the orbit of maximum axial tilt toward or away from the Sun—and the equinoxes, when the direction of the tilt and the direction to the Sun are perpendicular. In the Northern Hemisphere, winter solstice currently occurs around 21 December; summer solstice is near 21 June, spring equinox is around 20 March and autumnal equinox is about 22 or 23 September. In the Southern Hemisphere, the situation is reversed, with the summer and winter solstices exchanged and the spring and autumnal equinox dates swapped.
   Section::::See also.
  
  BULLET::::- Horae, Greek goddesses of seasons
  
  BULLET::::- Indian summer
  
  BULLET::::- Persephone, Greek mythological figure associated with the rebirth of vegetation in the spring
  
  BULLET::::- Sun path
  
  BULLET::::- Vertumnus, Roman god of the seasons
  
  Section::::References.
  
  BULLET::::- Maris, Mihaela, St. Luchian School, Bacau, Romania, "Seasonal Variations of the Bird Species", ref. ecological seasons pp. 195–196 incl. and pp. 207–209 incl.
  
  Section::::External links.
  
  BULLET::::- When do the Seasons Begin? (from the Bad Astronomer)
  
  BULLET::::- Why the Earth has seasons article on h2g2.
  
  BULLET::::- Aboriginal seasons of Kakadu
  
  BULLET::::- Indigenous seasons (Australian Bureau of Meteorology)
  
  BULLET::::- Mt Stirling Seasons
  
  BULLET::::- The Lost Seasons
   During May, June, and July, the Northern Hemisphere is exposed to more direct sunlight because the hemisphere faces the Sun. The same is true of the Southern Hemisphere in November, December, and January. It is Earth's axial tilt that causes the Sun to be higher in the sky during the summer months, which increases the solar flux. However, due to seasonal lag, June, July, and August are the warmest months in the Northern Hemisphere while December, January, and February are the warmest months in the Southern Hemisphere.
   Because the Earth's axis is tilted relative to its orbital plane, sunlight is incident at different angles at different times of the year. In June the Northern Hemisphere is tilted towards the sun, so at any given Northern Hemisphere latitude sunlight falls more directly on that spot than in December (see Effect of sun angle on climate). This effect causes seasons. Over thousands to hundreds of thousands of years, changes in Earth's orbital parameters affect the amount and distribution of solar energy received by the Earth and influence long-term climate. (See Milankovitch cycles).
   Any point north of the Arctic Circle or south of the Antarctic Circle will have one period in the summer called 'polar day' when the sun does not set, and one period in the winter called 'polar night' when the sun does not rise. At progressively higher latitudes, the maximum periods of "midnight sun" and "polar night" are progressively longer.
   Section::::Climate.
  
  The climate patterns of the Northern and Southern Hemispheres generally mirror each other. The trade winds in the southern and eastern Pacific are remarkably steady while conditions in the North Pacific are far more varied with, for example, cold winter temperatures on the east coast of Russia contrasting with the milder weather off British Columbia during the winter months due to the preferred flow of ocean currents.
   Section::::Seasons.:Summer.
   Other climate factors such as wind, humidity, atmospheric pressure, sunlight as well as diurnal temperature variations which can define different climate categories, can also have pronounced influences on the viticulture of an area.
  
  Section::::Mediterranean climates.
  