what is the definition of fall equinox?
599837
An equinox in astronomy is the moment when the Sun passes over the equator. The event occurs twice a year, around March 21 and September 23. The word equinox derives from the Latin word for equal night. The equinoxes are the two days each year when the middle of the Sun is an equal amount of time above and below the horizon for every location on Earth.\n\nIn the Northern Hemisphere, the March equinox is known as the vernal equinox and the September equinox is the autumnal equinox. In the Southern Hemisphere, the names are reversed.
650117
Same as the rest of the Northern Hemisphere:\n\nSpring: March\nSummer: June\nFall/Autumn: September\nWinter: December
876622
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.\n\nAs 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.\n\nSevere 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.\n\nThe 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.\n\nSpringtime 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.
817446
The ecliptic is defined as the path thourgh the sky where the sun appears over the course of the year.  Thus, no matter when you see the sun it is on the ecliptic.  On the equinoxes the ecliptic and the equator of the earth line up, and on those two days you can find the sun on the equator, but the sun is always on the ecliptic.
161048
Spring "officially" starts in the US on the day of the vernal equinox (it falls on March 20 this year)-- but spring-like weather can start before or after the equinox depending on the location.
951750
The two equinoxes (fall and spring) determine when the sun starts moving in the other direction and the two solstices (winter and summer) determine the shortest and longest days.  Your observation should continue to move in the direction as previously observed, but due to daylight savings time, the time will change...so get up earlier than 7 am to see what you want to see (sunrise for you will be at 7:14 am).
275393
The equinox is not a sudden event that flicks a switch or something, it's just the name we give to the instant when the equator is hit with direct sunlight.  It's simply a moment in a gradual cycle.\n\nEquinoxes: sun is directly over equator\nSummer Solstice (North): sun is directly over Tropic of Cancer\nWinter Solstice (North): sun is directly over Tropic of Capricorn
969676
lt is the season before winter.\n\nFall is also known as Autumn. \n\nWhen certain tree loose their leaves completely. Before loosing them lots of tree acquire very bright colour, people take time off to enjoy natures art work on the land scape it is a sight to behold, in many parts of the world.\n\nIn some Indian languages it will be PanKh-rd RooToo(Gujarati). In Gujarati  language, six seasons are accounted for, in USA, Europe, Australia they have four seasons, Summer, Fall or Autumn, Winter and Spring in this order.  \n\nIt starts in the northern Hemisphere early in August, way up north(Alaska) and if you are in Texas you can experience it in late November or early December as you go south fall is very short and it is not very distinct..\n\nIn Bombay India it is hardly experienced as the new  leaves bust  out very fast but you can see lots of leaves falling and leaves all over the place the order is also different Winter comes first and the fall the spring.......
1040359
In the fall.  September or October.
323013
I believe it has to do when solstice falls.  Not exactly sure though.  Good question.
503942
In the fall of this year. Probably between the months of September and October.\nThere is a 66.6% chance of it starting in September and a 33.3% chance of the season starting in October. (Roughly)
1130548
Winter Solstice has the least daylight: Dec 21. March 21 and September 21 are the vernal and autumnal equinoxes (when day = night = 12 hours). June 21 = the day with most daylight (in Northern Hemisphere).
15804
You have the dates wrong, and the dates do shift a bit.  The vernal equinox is usually March 20 but sometimes March 19.  The autumnal equinox is usually September 22 but sometimes September 23.  Theay are always half a solar year apart.  The shift has to do with the fact that the solar year is approximately 365-1/4 days long.  It's the same reason we have leap year.  I hope this answer helps!
273651
You can do that on ANY day of the year.  Nothing special about the equinox.  But nobody bothers to try on other days, thinking it can't be done.
462374
I believe the answer is, in the spring equinox, the earths shifts it axes 20% there by picking up moister from south of the equator, the westerly winds from the pacific ocean, and cold air fom the north.when all these elements colide, the cause a drastic change in moister form the collision from all three factors.It is why in the spring time there ae tornados in the south central states
182670
4 seasons to a year.  A season in the common sense is defeind by tepreature.  but a season in the technical sense is defined by the earth's tilt relative to your hemisphere.  They usually don't match; spring and fall are often too short.\n\nThe equinoxi are at June 21 and December 21; they mark the start of winter and summer in the northern hemisphere.  They are reversed in the southern hemisphere.  SPring and fall are halfway in between.
281704
" The Vernal Equinox "\n(official start of the spring season)\nMarch 20 at 1:26 pm EST\n=================\n10:26 am PST\n=================