LibertyBell

https://www.timeanddate.com/astronomy/equilux.html This article explains why day and night aren't equal on the equinox too. Equinox—Close, but Not Quite Equal Many of us think that an even balance of day to night happens during an equinox. After all, the word translates as “equal night.” So, a little confusion is understandable. But there’s a subtle time difference between an equinox and an equilux. Approx. equilux dates Latitude March September 60° North Mar 18 Sep 25 55° North Mar 17 Sep 25 50° North Mar 17 Sep 25 45° North Mar 17 Sep 25 40° North Mar 17 Sep 26 35° North Mar 16 Sep 26 30° North Mar 16 Sep 27 25° North Mar 15 Sep 27 20° North Mar 14 Sep 28 15° North Mar 12 Sep 30 10° North Mar 8 Oct 4 5° North Feb 24 Oct 17 Equator No equal day and night 5° South Apr 14 Aug 29 10° South Apr 1 Sep 10 15° South Mar 28 Sep 14 20° South Mar 26 Sep 16 25° South Mar 25 Sep 17 30° South Mar 24 Sep 18 35° South Mar 24 Sep 19 40° South Mar 23 Sep 19 45° South Mar 23 Sep 19 50° South Mar 23 Sep 20 55° South Mar 23 Sep 20 60° South Mar 22 Sep 20 Equal Light “Equilux” is drawn from the Latin terms for equal (equi) and light (lux). So how do we find out which dates fit the description and qualify as truly equal day and night? To measure the day/night split in a 24-hour span, astronomers use common definitions of sunrise and sunset. Simply put, sunrise is defined as when the first bit of the Sun’s disk appears and sunset is when the last bit of the disk vanishes. Calculating the length of day between those two moments, we find that two dates every year reach equilux in most latitudes. In the Northern Hemisphere, these happen a few days before the spring equinox (vernal equinox) and a few days after the autumn equinox. South of the equator, it's the other way around. A location's equilux dates depend on the latitude (see table). Locations on or near the equator never experience equal day and night. Imagine a Disk But why aren’t day and night of equal length at an equinox? To answer that question, it helps to think of the Sun in two different ways—as a disk and as a point. To pinpoint the days of equilux, the Sun is considered a disk, and we measure daytime from the first appearance of the Sun’s disk to the last bit slipping below the horizon. A Point at the Center of the Sun To calculate an equinox, on the other hand, the Sun is thought of as a single point, set in the center of the disk. An equinox occurs when the subsolar point—the spot on the Earth directly beneath the Sun—crosses the equator, equally straddling the Southern and Northern Hemispheres. On those days, the center point of the Sun indeed rises and sets 12 hours apart. But since we measure sunrise and sunset by thinking of the Sun as a disk, the top edge of the Sun appears a little earlier and sets a bit later than the center point. This difference creates a few extra minutes of daylight on the date of an equinox at most latitudes.

This is one of the reasons it doesn't match up with the solstice most of the time: https://www.timeanddate.com/news/astronomy/earth-fast-rotation-2025 Earth Will Spin Unusually Quickly in July and August Since 2020, Earth has notched up unprecedentedly short days midway through the year. It will happen again in 2025 around July 9, July 22, and August 5. Surprise! In recent years, Earth has been spinning a bit more quickly. Scientists are unsure why. ©NASA’s Goddard Space Flight Center Earth’s Variable Spin Speed Our planet is an almost-but-not-quite-perfect timekeeper. Every day, from the point of view of the Sun, Earth completes one full rotation on its axis in exactly 86,400 seconds, give or take a millisecond or so. 86,400 seconds is another way of saying 24 hours. A millisecond (ms) is 0.001 seconds—considerably less than a blink of an eye, which lasts around 100 milliseconds. The only way to measure these tiny day-to-day variations in Earth’s spin speed is with atomic clocks, which were introduced in the 1950s. The number of milliseconds above or below 86,400 seconds is known as length of day (LOD). Look it up: How long was yesterday? Earth Speeds Up Until 2020, the shortest LOD ever recorded by atomic clocks was -1.05 ms. This means that Earth completed one rotation with respect to the Sun in 1.05 milliseconds less than 86,400 seconds. Since then, however, Earth has managed to shatter this old record every year by around half a millisecond. The shortest day of all was -1.66 ms on July 5, 2024. Earth is expected to get close to this again in 2025 around July 9, July 22, and August 5. From the archive: Earth in a hurry (2020) The following table shows the shortest LOD in every year for the past five years, together with three possible dates for the shortest LOD in 2025. Shortest Length of Day, 2020–2025 Year Date LOD 2020 July 19 -1.47 ms 2021 July 9 -1.47 ms 2022 June 30 -1.59 ms 2023 July 16 -1.31 ms 2024 July 5 -1.66 ms 2025 July 9 -1.30 ms (prediction) 2025 July 22 -1.38 ms (prediction) 2025 August 5 -1.51 ms (prediction) Sources: timeanddate.com, IERS, USNO. Estimates are based on observations and models, and include systematic corrections and smoothing. Why Three Possible Dates? Short-term variations in LOD are affected by the orbit of the Moon. Our planet spins quicker when the Moon’s position is far to the north or south of Earth’s equator. The Moon will be around its maximum distance from Earth’s equator on the three possible dates for the shortest LOD in 2025. The following links for our Moon Light World Map show the Moon’s position—indicated by the Moon symbol—at 12:00 UTC on July 9, July 22, and August 5. Why Is All This Happening? Why has Earth accelerated, and when will it slow down again? These are difficult questions. Long-term variations in Earth’s spin speed are affected by a long list of factors that includes the complex motion of Earth’s core, oceans, and atmosphere. “Nobody expected this,” says Leonid Zotov, a leading authority on Earth rotation at Moscow State University. “The cause of this acceleration is not explained.” Most scientists believe it is something inside the Earth. Ocean and atmospheric models don’t explain this huge acceleration. Leonid Zotov

and I guarantee that NYC will be a lot closer to JFK than it would be to the Northern Bronx ;-) The Northern Bronx is like a lower Hudson Valley climate to me I remember 2/5/2010 we had 1.5 inches here and Staten Island had 6 inches. That's why we have snowfall ranges, for that storm 1-6 inches would have been a far range for the southern half of the city.

I think moving half an hour ahead is a fair compromise.

The longest day isn't really on the summer solstice, it's different days in different places depending on your latitude and some other factors. For us it's usually June 26th.

Possibly, but otherwise these weather *wars* will continue. If we could come up with a single number to describe the city it would dampen down biases any one individual station might have (NYC poorly sited, LGA/EWR running too hot, JFK seabreeze interference, etc.)

Do you think at least partially transferring the NWS/NOAA functions to private ownership would help matters? Perhaps we can get a rich billionaire who cares about climate and weather to fund a supercomputing system sufficiently powerful to run 4dVar? I'm being ironic, I don't think any of them care, but the funding has to come from somewhere and we have a few billionaires funding space trips so why not get them to invest in climate and weather too? Note how NASA has partnerships with these private space companies, maybe NWS and NOAA need to do the same thing? Public funding only gets you so far and we are in the era when people want to spend less and save more, so maybe we are on the way to privatizing everything now and shifting the burden to those who can afford it....

The solution is to average out NYC, EWR, JFK, LGA and then you get the full of range of weather in New York City (which covers 5 boroughs). I believe LGA runs too hot now, look at how elevated their lows are compared to everyone else and it has the highest concentration of traffic now, which is much worse now than it was during the 30s-50s period when NYC was hotter (as was JFK.)

tomorrow is the first day of summer around 10:30 am? Just in time!

I also think there is a direct connection between seabreeze summers and winters in which the coast gets less snow, the processes are very similar.

were you living down here back then? I remember you said you lived on Long Island growing up I think.

so similar to 1993 but of a somewhat lower magnitude? That was one of those summers that was hotter the further west you went unlike 1993 which was hot throughout everywhere, my favorite summer before 2010. 1994 was more like 1988.

Yes, it did make landfall here, I wonder why no one ever talks about that, was it a minimal tropical storm when it was making landfall here?

1972 - Hurricane Agnes moved onshore near Cape San Blas FL with wind gusts to 80 mph, and exited Maine on the 26th. There were 117 deaths, mainly due to flooding from North Carolina to New York State, and total damage was estimated at more than three billion dollars. Up to 19 inches of rain deluged western Schuylkill County PA. The rains of Hurricane Agnes resulted in one of the greatest natural disasters in U.S. history. Agnes caused more damage than all other tropical cyclones in the previous six years combined (which included Celia and Camille). (David Ludlum) (The Weather Channel) Didn't Agnes also make a landfall near JFK Tony? 1794: A violent tornado commenced west of the Hudson River in New York. The tornado traveled through Poughkeepsie then crossed the border into Connecticut where it went through the towns of New Milford, Waterbury, North Haven, and Branford. It then continued into Long Island Sound. The tornado did extensive damage, and the funnel was reported by one observer to look like the "aurora borealis." <<< this must have been an F3 at least 1835 - A tornado tore through the center of New Brunswick NJ killing five persons and scattering debris as far as Manhattan Island. The tornado provided the first opportunity for scientists to study firsthand the track of such a storm. (David Ludlum) <<< this sounds like an F3 too also wow, you don't see stuff like this in this region anymore. and this must have been the peak of the heat in 1994, July and August were not this hot for us (but very hot for Philly.) Not historical like 1993, but just a step below it. Highs: EWR: 103 (1994) NYC: 98 (1994) LGA: 97 (1994) JFK: 98 (1994)

people who love blue skies and sunshine. find an a/c to stand near

our modern farming practices are horrible, we need to completely defund the corn and soybean cartels and we need more super derechos to take them down. why is the Pac NW getting the drought and not us? They have an ocean to their west and the flow is west to east and we have an entire continent to our west, shouldn't they be getting the excessive rains and we getting the drought? 1995 was an extremely hot summer in the midwest. The 1990s really were like the 1930s-1950s era for big summer heat, we haven't seen that kind of consistent heat since (though we did see it briefly from 2010-2013.)

Maybe the excessive rainfall from CC has caused this foliage overgrowth..... looking at my front yard, I think this is the correct idea. NYC had much less rainfall and a much drier climate during the 1930s-1960s with less foliage in our parks, so it was much easier to get record heat back then.

westerly flow would mean 100+ right to JFK

Yep, hasn't rained at all since yesterday morning. The switch has flipped.

this really is more of a tropical rainforest type of climate, in that kind of climate, you do not get extremely high temperatures because most of the heat is absorbed by the excess moisture in the atmosphere (which creates those high rainfall events later on in the summer.) Maybe this predominant sea breeze is a function of climate change, as the planet seeks to balance out the differences between land and ocean?

we had it in the morning you're getting it now.

I agree, I guess I am asking that if the chances are higher than normal for both NYC and JFK to hit 100 degrees at least once in July, like they did during the 2010-2013 era.

any early call on July, Don? a continuation of the heat? do you think it will reach the magnitude of 2010-2013 or will it be somewhat less than that?

sounds like a wonderful place to see a rainbow from (we usually see rainbows here just before sunset.)

we had a 5 inch sleet storm here in the middle of March lol