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Monday, September 22, 2014

Happy Autumnal Equinox!


Autumn begins on Tuesday, September 23, 2014
and ends on Sunday, December 21, 2014


Things I  didn't know about Fall, did you?
Meteorologists consider September 1 the first day of Autumn.
But for those who prefer defining the seasons by astronomy, the autumnal equinox, which occurs
Monday night at 10:29 p.m. ET,
marks the end of summer and
the beginning of Fall in Earth’s Northern Hemisphere.
1. Nearly equal daylight in both hemispheres
During the fall equinox, the sun can be seen at zenith before its direct rays shift into the Southern Hemisphere for the next six months. Neither of Earth’s hemispheres is tilted toward the sun, which results in roughly 12 hours of daylight and darkness at all
latitudes      


2. Sunrise at due east, Sunset at due west 
Except at the North and South Pole, all latitudes on Earth see the sun rise at due east and set at due west on the September equinox. Until the winter solstice in December, the sun will continue to rise and set farther to the south
3. Fastest loss of daylight
Mid-latitudes of the Northern Hemisphere see the greatest loss of daylight around the fall equinox.  At higher latitudes, the decrease in daylight is even more pronounced.
4. Not quite equal day and night
A common misconception is that the equinox means equal day and night everywhere on Earth. In reality, this isn’t quite true.  Not until September 26, 2014 are sunrise and sunset exactly 12 hours apart. The main reason for this is atmospheric refraction, an optical phenomenon that allows us to see the sun even when it’s below the horizon. Most places in the Northern Hemisphere therefore don’t see an exact 12-hour day until after the autumnal equinox, typically between Sept. 25-28.
5. Fastest Sunsets and shortest twilight of the year
Careful sun observers may notice that around the fall equinox it gets dark not only earlier but also faster. And they’re right – the fastest transitions between day and night occur around the two equinoxes. This happens because the sun crosses the horizon at a slightly steeper angle than it does on the solstices. As a result, we see the sun appear and disappear from the horizon more quickly. The difference is subtle closer to the equator, but is much more noticeable in high latitudes.
6. A warmer version of the Spring Equinox
Due to seasonal temperature lag, the Autumnal Equinox in the Northern Hemisphere is generally much warmer than the Spring equinox in March – even though both days receive the same amount of incoming solar energy. Since oceans cover 71 percent of the planet, and water takes longer than air to heat up and cool down, it takes a while for the Northern Hemisphere to respond to a drop in incoming solar energy. This is why even though the days are shorter, it’s not uncommon to get a period of summer-like weather in October.
Yet, while Autumn is known for its pleasant weather, the September Equinox is a melancholy reminder that we’ll be seeing much less of the sun for the next six months.

More lovely Fall images for you to enjoy

now sit and relax......



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