Warmer, wet and the Equinox explained
This morning it is partly cloudy with a chance of rain. Fog early. High of 70F. Winds from the West at 5 to 15 mph. Chance of rain 20%.
Tonight it will be clear with an expected low of 43F. Winds from the WNW at 5 to 10 mph.
The readings from my own weather instruments are:
The humidity is 92% with a Dew Point of 62ºF, Temp is 62.8ºF and the wind chill is 62.8ºF.
Our wind direction is South between 0.2 MPH and 1.0 MPH.
Our Barometric pressure is 29.59 HPA 1000 and falling with a weather graphic indicating rain.
The UV rating is 0 out of 16, Sunrise is at 6:26 a.m. sunset is 6:36 PM and Moon Rise is at 4:49 a.m. EDT and the moon phase is waning crescent.
For the pilots out there raw metar is:
METAR KAUG 221053Z AUTO 23003KT 10SM FEW042 SCT070 SCT100 17/17 A2953 RMK AO2 RAB35E46 SLP997 P0000 T01670167
Visibility is 10.0 miles/16.1 Kilometers with scattered clouds to 7000 ft / 2133 m.
We received rain in the amount of 0.14 here over the past 24 hours
The Autumnal Equinox is tonight at 10:29 P.M.
If you want to know more of what an Equinox is, go to Wickipedia and read all about it. What appears below is what I took to be the "high points" of it, but there is more.
• Vernal equinox and autumnal equinox: these classical names are direct derivatives of Latin (ver = spring and autumnus = autumn). These names are based
on the seasons, and can be ambiguous since seasons of the northern hemisphere
and southern hemisphere are opposites, and the vernal equinox of one hemisphere is the autumnal equinox of the other.
• Spring equinox and fall equinox or autumn equinox: these are more colloquial names based on the seasons, and are also therefore ambiguous across hemispheres.
• March equinox and September equinox:
names referring to the times of the year when such equinoxes occur. These are without the ambiguity as to which hemisphere is the context, but are still not universal as not all people use a solar-based calendar where the equinoxes occur every year in the same month (as they do not in the Islamic calendar and Hebrew calendar, for example), and the names are not useful for other planets (
Mars, for example), even though these planets do have seasons.
• Northward equinox
And southward equinox:
names referring to the apparent motion of the Sun at the times of the equinox. The least culturally biased terms.
• Vernal point and autumnal point are the points on the celestial sphere where the Sun is located on the vernal equinox and autumnal equinox respectively.
Usually this terminology is fixed for the Northern hemisphere.
• First point (or cusp) of Aries and first point of Libra are names formerly used by astronomers and now used by navigators and
astrologers.
Navigational ephemeris tables record the geographic position of the First Point of Aries as the reference for position of navigational stars. Due to the precession of the equinoxes, the astrological signs of the tropical zodiac where these equinoxes are located no longer correspond with the actual constellations once ascribed to them. The equinoxes are currently in the constellations of Pisces And Virgo.
In sidereal astrology (notably Hindu astrology), by contrast, the first point of Aries remains aligned with Ras Hammel "the head of the ram", i.e. the Aries constellation.
Length of equinoctial day and night Hours_of_daylight_vs_latitude_vs_day_of_year_cmglee
Enlarge Contour plot of the hours of daylight as a function of latitude and day of the year, showing approximately 12 hours of daylight at all latitudes during
the equinoxes
On the day of the equinox, the center of the Sun spends a roughly equal amount of time above and below the horizon at every location on the Earth, so night and day are about the same length. The word equinox derives from the Latin words aequus (equal) and nox (night). In reality, the day is longer than the
night at an equinox. Day is usually defined as the period when sunlight reaches the ground in the absence of local obstacles. From the Earth, the Sun appears
as a disc rather than a point of light, so when the center of the Sun is below the horizon, its upper edge is visible. Furthermore, the atmosphere refracts light, so even when the upper limb of the Sun is 0.4 degrees below the horizon, its rays curve over the horizon to the ground. In sunrise/sunset tables, the assumed semidiameter (apparent radius) of the Sun is 16 minutes of arc and the atmospheric refraction is assumed to be 34 minutes of arc. Their combination means that when the upper limb of Sun is on the visible horizon, its center is 50 minutes of arc
below the geometric horizon, which is the intersection with the celestial sphere of a horizontal plane through the eye of the observer. These effects make the day about 14 minutes longer than the night at the Equator and longer still towards the Poles. The real equality of day and night only happens in places far enough from the Equator to have a seasonal difference in day length of at least 7 minutes, actually occurring a few days towards the winter side of each equinox.
Because the Sun is a spherical (rather than a single-point) source of light, the actual crossing of the Sun over the Equator takes approximately 33 hours.
At the equinoxes, the rate of change for the length of daylight and night-time is the greatest. At the poles, the equinox marks the start of the transition from 24 hours of nighttime to 24 hours of daylight (or vice versa). Far north of the
Arctic Circle, At Longyearbyen, Svalbard, Norway, there is an additional 15 minutes more daylight every day about the time of the Spring equinox, whereas in Singapore (which is just one degree of Latitude north of the Equator), the amount of daylight in each daytime varies by just a few seconds.
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