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Spring (season)

2007 Schools Wikipedia Selection. Related subjects: Climate and the Weather;
Everyday life

                                                          CAPTION: Seasons

                                                                  Tropical

                                                                Dry season

                                                                Wet season

                                                          CAPTION: Seasons

                                                                 Temperate

                                                                    Spring

                                                                    Summer

                                                                    Autumn

                                                                    Winter

   Spring is one of the four seasons of temperate zones, the transition
   from winter into summer. Astronomically, some Western countries
   consider spring to begin with the spring equinox (around March 20 in
   the Northern Hemisphere, and September 23 in the Southern Hemisphere),
   and ends with the summer solstice (around June 21 in the Northern
   Hemisphere and December 21 in the Southern Hemisphere). Such
   conventions are by no means universal, however. In Chinese astronomy,
   for example, the vernal equinox instead marks the middle of spring,
   which begins around the time of Lichun (around February 4). In the
   Irish Calendar it is counted as the whole months of February, March and
   April. In meteorology, it is (also by convention) instead counted as
   the whole months of March, April, and May in the Northern Hemisphere
   and September, October, and November in the Southern Hemisphere.

   As in summer, the axial tilt of the Earth is toward the Sun, and
   daylight hours are greater than or equal to 12 hours and rapidly
   increasing (especially in higher latitudes). The hemisphere begins to
   warm significantly, causing new plant growth to spring forth, giving
   the season its name (see Effect of sun angle on climate). Snow (if any)
   begins to melt, and rivers and streams swell with runoff and spring
   rains. Most flowering plants bloom this time of year, in a long
   succession beginning even when snow is still on the ground, and
   continuing into early summer. In normally snowless areas, "spring" may
   begin as early as February during warmer years, with subtropical areas
   having very subtle differences, and tropical ones none at all.
   Subarctic areas may not see "spring" at all until May or even June, or
   December in the outer Antarctic.
   Carl Larsson, Våren (The Spring), 1907
   Enlarge
   Carl Larsson, Våren (The Spring), 1907
   Enlarge

   Severe weather most often occurs during the spring, when warm air
   begins to invade from lower latitudes while cold air is still pushing
   from the polar regions. Flooding is also most common in and near
   mountainous areas during this time of year due to snowmelt, many times
   accelerated by warm rains. In the United States, Tornado Alley is most
   active by far this time of year, especially since the Rocky Mountains
   prevent the surging hot and cold airmasses from spreading westward and
   instead force them directly at each other. Besides tornados, supercell
   thunderstorms can also produce dangerously large hail and very high
   winds, for which a severe thunderstorm warning or even tornado warning
   is usually issued. Often, spring storms trigger dozens of warnings, one
   right after the other, often simultaneously along a line hundreds of
   miles or kilometers long. Even more so than winter, the jet streams
   play an important role in severe weather in the springtime.

   The hurricane season officially begins in late spring, on May 15 in the
   northeastern Pacific, and June 1 in the northern Atlantic. Before these
   dates, hurricanes are almost unheard of and even tropical storms are
   rare, one of the earliest ever being Tropical Storm Ana in mid-April
   2003. Even in June, hurricanes are uncommon.

   Springtime is seen as a time of growth, renewal, of new life (both
   plant and animal) being born, and of the cycle of life once again
   starting. It is also used more generally as the start of better times,
   as in Prague Spring.

   Retrieved from " http://en.wikipedia.org/wiki/Spring_%28season%29"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
