What is Fall: Definition and 922 Discussions

Autumn, also known as fall in North American English, is one of the four temperate seasons. Outside the tropics, autumn marks the transition from summer to winter, in September (Northern Hemisphere) or March (Southern Hemisphere), when the duration of daylight becomes noticeably shorter and the temperature cools considerably. Day length decreases and night length increases as the season progresses until the Winter Solstice in December (Northern Hemisphere) and June (Southern Hemisphere). One of its main features in temperate climates is the shedding of leaves from deciduous trees.
Some cultures regard the autumnal equinox as "mid-autumn", while others with a longer temperature lag treat the equinox as the start of autumn. In the English-speaking world, autumn traditionally began with Lammas Day and ended around Hallowe'en, the approximate mid-points between midsummer, the autumnal equinox, and midwinter. Meteorologists (and Australia and most of the temperate countries in the southern hemisphere) use a definition based on Gregorian calendar months, with autumn being September, October, and November in the northern hemisphere, and March, April, and May in the southern hemisphere.
In North America, autumn traditionally starts with the September equinox (21 to 24 September) and ends with the winter solstice (21 or 22 December). Popular culture in the United States associates Labor Day, the first Monday in September, as the end of summer and the start of autumn; certain summer traditions, such as wearing white, are discouraged after that date. As daytime and nighttime temperatures decrease, trees change colour and then shed their leaves. In traditional East Asian solar term, autumn starts on or around 8 August and ends on or about 7 November. In Ireland, the autumn months according to the national meteorological service, Met Éireann, are September, October and November. However, according to the Irish Calendar, which is based on ancient Gaelic traditions, autumn lasts throughout the months of August, September and October, or possibly a few days later, depending on tradition. In the Irish language, September is known as Meán Fómhair ("middle of autumn") and October as Deireadh Fómhair ("end of autumn"). Persians celebrate the beginning of the autumn as Mehregan to honor Mithra (Mehr).

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  1. H

    Roller coasters: would we fall out without restraints?

    I ask because as you might have heard recently a person fell out of a roller coaster when her restraint came open last week in Ohio. I was always told that the physics of these ride designs made it so that the people would be safe even without a restraint. I'm skeptical about a few things...
  2. O

    Is this Fall schedule doable for a Physics/Math student aiming for all A's?

    Fall Schedule 2013, URGENT HELP Hello all, I am new to the Physics forum (hence if this post is in the wrong place, you know why). My current dilemma is my schedule for this Fall, I go to a mid-sized state university with a small Physic department. My school does not offer PhD or even a...
  3. J

    Take fall semester off to study for PGRE?

    So the way my schedule is looking, I will be finished after a fall semester. Now I want to do an REU during that summer leading into the fall, so I won't really be studying then, which is from what I understand, when most people do their studying for the PGRE. Would it be best to postpone my...
  4. S

    Why do objects fall through curvature of spacetime?

    Just wondering, if the way to describe the movement of objects through spacetime is to say that they fall through the curves created in 4D spacetime, then is it a stupid question to ask why objects don't rise through spacetime? Or is this the same thing and rising and falling are one of the same...
  5. W

    So I'm going to take Jackson in the fall.

    I've heard many horror stories. Any tips? Any specific parts of Griffiths I should be extra keen on? Is the answer...*sigh*... "all of it backwards and forwards"?
  6. H

    Minimum acceleration needed for box to not fall from accelerating cart

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  7. M

    Suggest Classes for Fall Semester Electrical Engineering Degree

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  8. E

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  9. X

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  10. C

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  11. C

    Distance from earth an object would have to fall from to reach speed x

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  12. F

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  13. M

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  14. J

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    Yes, yes I did my homework - I googled this and got many results but none seem to answer my query. I am not a historian so bear with me. I had a picture in my mind that civilizations seem to appear after we discovered agriculture and thereafter each civilization advanced and continued to...
  15. D

    Time for Object to Fall Based on Center of Gravity

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  16. P

    Exploring Free-Fall Acceleration: Understanding the Basics in a Logical Method

    hi, thanks for taking time to read my first post. i'm trying to solve a little mystery and would like to do so in a methodical and logical way. it is my basic understanding that free-fall acceleration is a constant on Earth of 9.8m/sec2 that if an object is released from a height it...
  17. Gliese123

    Will all proteins fall apart by exaggerated heat?

    Like the topic; if you boil proteins (or vitamines for that matter), will the molecular structure break? For example warm milk etc.
  18. X

    What do you think of my schedule for fall 2013?

    Electricity and Magnetism 1-Griffith level Quantum Mechanics-1 Griffith Mathematical Physics II topics are mostly PDE's and complex Analysis And either Solid State physics or intro to Cosmology. Both classes are senior or junior level Do you guys think this is a decent schedule for a...
  19. J

    Physics IA, Statics, and Cal III in the fall - doable?

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  20. L

    QM: Potential Energy & Particle Free Fall

    In classical mechanics is defined potential and kinetical energy for particular particle. For example, in case of free fall potential energy of the particle is ##mgh## and kinetic energy is ##\frac{m\upsilon^2}{2}##. In QM there isn't potential of the particle, but potential of part of the...
  21. B

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    Say I have a special type of black hole, an infinetly small one. I am standing still in deep space and i let a point mass to fall. What is it's equation of motion? I'm interested in the equation itself not just an explanation. It should be sth like this x=f(t).
  22. J

    Can You Engineer an Egg Drop Device to Survive a 14m Fall?

    Homework Statement I have to make an egg drop device. I was fishing for ideas. It needs to be the fastest time and survive the fall. If I win I get 4 points E.C.. Homework Equations Impulse = Ft Position function for falling object s(t) = -16t^2 +Vo + So s'(t) = -32t F = ma p =...
  23. sergiokapone

    How High Must a Rod Fall to Hit a Table Elastically at Both Ends?

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  24. L

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  25. K

    Change in Gravity Affecting Free Fall

    In high school physics, which I am in, we learn that to find the distance that and object falls can be found with the equation, x=v0t+1/2gt2. We also learn that the force of gravity between two objects can be found by Fg=Gm1m2/r2 and thus acceleration due to gravity can be derived to be g=Gm/r2...
  26. D

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  27. harrylin

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  28. A

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  29. J

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  30. B

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  31. N

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  32. W

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  33. K

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  34. rjbeery

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  35. S

    Time for a Droplet of Water to Fall .25m from Hole

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  36. T

    When does a ball enter free fall?

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  37. AakashPandita

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  38. D

    Why Do Objects Fall if Gravity Isn't a Force in General Relativity?

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  39. S

    Free Fall Questions Homework: Gravity, Drag, Force & Parachutes

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  40. B

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  41. D

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  42. S

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  43. N

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  44. E

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  45. mishima

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  46. H

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  47. Anna Blanksch

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  48. A

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  49. S

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