It is Christmas Morning and already I am on the hard stuff: pate and cheese.
The cheese is a made in Quebec variety. With green tea. Celebrated with an elaborate meal
last night so I will be prudent today... Ha!
So my Christmas wishes for 2025 will automaticaaly post at 5 A.M. tomorrow morning,
the 24th od December. Why that is...
Copilot:
At what date and time for Montreal does it start being Christmas over the dateline?
Here’s the clean, time‑zone‑grounded answer, Louise.
🎄 When does Christmas begin anywhere on Earth, in Montreal time?
The first place on Earth to reach December 25 at 00:00 is Kiritimati (Christmas Island), Kiribati, which uses UTC+14.
Montreal in late December is on Eastern Standard Time (UTC‑5).
The time difference between Montreal and Kiritimati is 19 hours (Kiritimati is ahead).
🕒 Convert midnight Christmas in Kiritimati → Montreal time
Montreal time=Kiritimati time−19 hours
So:Kiritimati: December 25, 00:00
Minus 19 hours → Montreal: December 24 at 05:00
✅ Final Answer
Christmas begins anywhere on Earth at 05:00 AM on December 24 in Montreal.
If you want, I can map out the whole sequence of when each region hits Christmas relative to Montreal—it’s surprisingly fun to see the wave roll across the planet.
...
Please map out the global sequence...
Absolutely, Louise — here is the full global sequence of when Christmas arrives around the world, expressed in Montreal time, using the 19‑hour lead of Kiritimati shown on the page you were viewing.
I’ll keep it clean, chronological, and intuitive — a true “wave of Christmas” sweeping across the planet.
🎄 When Christmas Arrives Worldwide (in Montreal Time)
Montreal = UTC‑5 in December
The world’s time zones range from UTC+14 down to UTC‑12, so Christmas takes 26 hours to sweep across the planet.
Below is the exact order.
🎉 Summary
Christmas begins on Earth at 05:00 AM Dec 24 in Montreal (Kiritimati)
Christmas ends on Earth at 07:00 AM Dec 25 in Montreal (Baker/Howland Islands)
Total sweep: 26 hours
If you want, I can also generate:
A visual timeline
A map‑style textual walkthrough
A Montreal‑centric countdown table for any specific region
Just tell me what format you’d enjoy most.
The Shimmering Specks code Copilot gave me yesterday is veyr useful; I will be
spending some time today understanding it completely. One can make some changes
on the colors:
Making the size of the shimmers smaller:
It's one of those magical evenings where the light is shimmering on the snow. I asked
Copilot for python code with this shimmer effect. One can adjust the parameters and run it
on top of an image:
DeepSeek on Milankovitch cycles:
Describe to me the three Milankovich cycles...
Of course. The Milankovitch cycles (note: often anglicized as "Milankovitch" but originally Milanković) are three cyclical changes in Earth's orbital and rotational characteristics that combine to influence long-term climate patterns, especially the timing of glacial and interglacial periods over hundreds of thousands of years. They are named after Serbian geophysicist and astronomer Milutin Milanković, who mathematically described them in the early 20th century.
Here are the three main cycles, from shortest to longest period:
1. Eccentricity (Orbital Shape Cycle)
What it is: The change in the shape of Earth's orbit around the Sun, from more circular to more elliptical (eccentric).
Time Period: Approximately 100,000 and 400,000 years for the main cycles.
Mechanism: The gravitational pull of other planets, primarily Jupiter and Saturn, slowly stretches and squeezes Earth's orbit.
Climate Effect: Alters the total solar radiation (insolation) Earth receives over a year. When the orbit is highly elliptical, there is a significant difference in solar energy received at perihelion (closest approach) versus aphelion (farthest point). Currently, Earth's orbit is mildly elliptical, with about a 6% difference in solar receipt. At maximum eccentricity, this difference can be around 23%.
2. Obliquity (Axial Tilt Cycle)
What it is: The change in the tilt of Earth's rotational axis relative to its orbital plane. Think of it as the "wobble" in the tilt.
Time Period: Approximately 41,000 years.
Mechanism: The tilt oscillates between about 22.1 degrees and 24.5 degrees (it is currently 23.4 degrees and decreasing).
Climate Effect: This is the main driver of seasonal contrast. A greater tilt means more extreme seasons—warmer summers and colder winters at high latitudes. This is critical for ice sheet growth/decay: cooler summers in the high northern latitudes (where most land is) are key to preventing summer melt of ice, allowing glaciers to advance.
3. Precession (Axial Wobble & Orbital Precession)
What it is: A dual motion often called the "wobble" of the spinning top.
Axial Precession: The slow, circling wobble of Earth's rotational axis (like a spinning top winding down), completing a full circle.
Apsidal Precession: The slow rotation of Earth's elliptical orbit itself.
Time Period: Approximately ~23,000 years for the full cycle (often rounded to 26,000 for axial precession alone, but the combined climatic effect cycle is ~23,000 years).
Mechanism: Caused by gravitational tugs from the Sun and Moon on Earth's equatorial bulge.
Climate Effect: Changes the timing of the seasons relative to Earth's position in its orbit. It determines whether a given hemisphere's summer or winter occurs at perihelion (closest to the Sun) or aphelion (farthest). For example, about 11,000 years ago, Northern Hemisphere summer was at perihelion (making it warmer). Today, Northern Hemisphere summer is at aphelion, making it slightly milder.
How They Combine to Drive Ice Ages
The key concept is that these cycles do not cause large changes in the total annual solar energy, but they dramatically redistribute it by latitude and, crucially, by season. The dominant theory is that glaciations are triggered by cool summers in the high northern latitudes, which allow winter snow to persist and accumulate into continental ice sheets over thousands of years.
The 41,000-year obliquity cycle was dominant in climate records until about 1 million years ago.
For the last million years, the 100,000-year eccentricity cycle has become dominant in pacemaking the major ice ages, although its direct effect is the weakest. This suggests a strong nonlinear feedback within the climate system (e.g., ice-albedo feedback, CO₂ release from oceans) that amplifies the small initial trigger.
Important Caveats
Pacemaker, Not Driver: Milankovitch cycles provide the consistent pace for the glacial-interglacial cycles, but they are not the sole cause. The initial orbital change is small; it must be amplified by feedbacks (like changes in greenhouse gas concentrations—CO₂ and CH₄—and ice-albedo feedback) to produce the large temperature swings we see in the paleoclimate record.
Not Relevant for Modern Climate Change: These cycles operate on timescales of tens of thousands of years. The current, rapid global warming is happening 100 times faster than warming at the end of past ice ages and is unequivocally driven by human emissions of greenhouse gases, not by these slow orbital changes.
In summary: The Milankovitch cycles are the long-term astronomical "clockwork" of Earth's climate, altering the geographical and seasonal distribution of solar energy, which, when amplified by Earth's own climate feedbacks, sets the rhythm of the Ice Ages.
* * *
Precession is when a the axis of a rotation rotates in turn to another set of forces...
How does the Earth's excentricity change over 100,000 years?
Here’s the clear, evidence‑based picture, Louise — grounded directly in the sources we just pulled.
🌍 How Earth’s eccentricity changes over ~100,000 years
Earth’s eccentricity is the measure of how stretched (elliptical) or circular its orbit is.
It varies cyclically over long timescales, and the dominant cycle is about 100,000 years.
🔄 1. The orbit oscillates between more circular and more elliptical
According to Milankovitch‑cycle research, Earth’s eccentricity varies between about:
0.005 (very circular)
0.058 (noticeably elliptical)
This range and cycle length are described in the Milankovitch literature.
🕰️ 2. The main cycle is ~100,000 years
Multiple sources confirm that eccentricity follows a roughly 100,000‑year periodicity.
This is the same timescale associated with the pacing of ice ages.
📉 3. What the cycle actually looks like
Over a full 100,000‑year cycle:
Eccentricity increases gradually as gravitational interactions with Jupiter and Saturn stretch Earth’s orbit.
It reaches a maximum (more elliptical).
Then it decreases again as orbital resonances shift, returning the orbit toward a more circular shape.
This rise‑and‑fall pattern repeats, though not perfectly smoothly — it’s a combination of several overlapping cycles (95k, 125k, and 400k years), but the 100k cycle dominates.
❄️ 4. Why it matters
Changes in eccentricity alter:
How much solar energy Earth receives over the year
The contrast between seasons
The strength of precession’s effect on climate
This is why eccentricity is a major driver of the glacial–interglacial rhythm over the last few million years.
📌 Summary (in one sentence)
Earth’s eccentricity slowly oscillates between nearly circular and mildly elliptical over a dominant 100,000‑year cycle, strongly influencing long‑term climate patterns.
If you want, I can plot:
eccentricity over the last 800,000 years,
eccentricity over the next 200,000 years,
or a simplified sinusoidal model showing the 100k‑year cycle.
Just tell me which direction you want to explore.
What shape corresponds to a glacial period?
Here’s the clean, evidence‑based answer, Louise — grounded in what Milankovitch‑cycle science actually says.
🧊 What shape corresponds to a glacial period?
A glacial period corresponds to the part of Earth’s orbital‑climate cycle where global ice volume is high, temperatures are low, and ice sheets expand.
In climate data, this shows up as a long, slow cooling and ice‑growth phase, followed by a sharp, rapid warming into an interglacial.
This pattern is often described as:
A “sawtooth” shape
Long, gradual descent into a glacial period
Short, abrupt rise out of it (deglaciation)
This sawtooth pattern is visible in ice‑core and sediment records of past glacial cycles, which are paced by orbital variations described in Milankovitch theory.
🌍 Why the shape is sawtooth
Milankovitch cycles — eccentricity, obliquity, and precession — modulate how sunlight is distributed across seasons and latitudes.
Research shows:
Glacial buildup is slow because cooling and ice‑sheet growth are self‑reinforcing.
Deglaciation is fast because once summer insolation increases enough, ice sheets collapse rapidly.
This asymmetric response is discussed in studies of Pleistocene glacial cycles.
🧭 Summary
Glacial periods correspond to the long, downward slope of the sawtooth curve — the slow cooling and ice‑growth phase.
Interglacials correspond to the sharp upward spike.
If you want, I can show you:
a graph of the last 800,000 years of glacial cycles,
a simplified sawtooth model,
or how eccentricity, tilt, and precession combine to produce that shape.
More eccentric vs less so; which is it for a glacial age?
Here’s the crisp, evidence‑based answer, Louise — grounded directly in the sources we just pulled.
❄️ Glacial ages occur when Earth’s orbit is less eccentric (more circular)
The key mechanism is this:
When eccentricity is low (orbit nearly circular), precession has very little effect, so summer insolation at high latitudes stays low for many thousands of years.
Persistently weak summers allow ice sheets to grow, pushing Earth into a glacial period.
This relationship is described in Milankovitch‑cycle science, which links eccentricity changes to glacial–interglacial pacing.
🌍 Why low eccentricity favors glaciation
1. Low eccentricity = weak seasonal contrast
When the orbit is nearly circular:
Earth–Sun distance barely changes through the year.
Summers at 65°N (the critical latitude for ice-sheet stability) stay cooler.
Cool summers → snow survives → ice sheets grow.
2. Precession becomes ineffective
Precession (the wobble of Earth’s axis) only matters when eccentricity is high.
When eccentricity is low, precession can’t significantly change summer sunlight.
So the climate gets “stuck” in a cold configuration.
3. Ice ages cluster around eccentricity minima
This is why the 100,000‑year eccentricity cycle aligns with the pacing of major glacial cycles:
eccentricity minima create long intervals where ice sheets can expand.
🌡️ What about high eccentricity?
High eccentricity (more elliptical orbit):
Increases the effect of precession.
Can produce very strong summers in one hemisphere.
These strong summers melt ice sheets, helping trigger interglacials.
So:
Low eccentricity → glacial periods
High eccentricity → easier deglaciation / interglacials
This is consistent with the eccentricity range (0.005–0.058) over 100,000‑year cycles.
📌 Final answer
Glacial ages correspond to low eccentricity — when Earth’s orbit is most circular.
If you want, I can show you:
a plot of eccentricity vs glacial cycles,
eccentricity over the last 800,000 years,
or a simple model showing why low eccentricity suppresses precession’s warming effect.
Just tell me where you want to go next.
Where are we now with respect to eccentricity?
Here’s the clear, up‑to‑date answer, Louise — grounded directly in the search results.
🌍 Where Earth’s eccentricity is right now
Earth’s current orbital eccentricity is approximately:
𝑒≈0.0167
This value appears in multiple sources, including the definition of Earth’s orbital eccentricity and the J2000 reference value of 0.01671022 from NASA data.
So today, Earth’s orbit is:
Only slightly elliptical
Much closer to the circular end of its long‑term range (0.005–0.058)
📉 Where this sits in the 100,000‑year cycle
Earth’s eccentricity oscillates between 0.005 (very circular) and 0.058 (more elliptical) over ~100,000‑year cycles.
With today’s value of 0.0167, we are:
👉 Near the low end of the cycle
Earth’s orbit is currently much more circular than average.
This matters because:
Low eccentricity weakens precession’s effect,
Which tends to favor glacial conditions (in the long-term Milankovitch sense),
Though modern climate is dominated by human forcing, not orbital forcing.
🧭 Summary
Current eccentricity: ~0.0167
Position in cycle: Near a minimum (orbit nearly circular)
Long-term trend: Eccentricity is slowly decreasing toward its next minimum
If you want, I can show you:
a plot of eccentricity over the last 800,000 years,
where eccentricity will be in 10,000 or 50,000 years,
or how eccentricity interacts with precession to shape glacial cycles.
When should Ice Age conditions peak?
Here’s the clearest, evidence‑based answer we can give right now, Louise — grounded directly in the search results.
🧊 When should Ice Age conditions peak naturally?
Based on current Milankovitch‑cycle research, the next major glacial maximum — the peak of an Ice Age — would naturally occur tens of thousands of years from now, with the onset beginning roughly 10,000 years from today.
Here’s what the sources say:
🌍 1. Natural orbital forcing would push Earth toward glaciation in ~10,000 years
Multiple studies indicate that, without human influence, Earth would begin drifting back into glacial conditions around 10,000 years from now:
Scientists note that “Earth would shift toward another ice age in about 10,000 years”.
Space.com reports that “the next ice age is coming in 10,000 years — unless climate change prevents it”.
This refers to the onset of glaciation — the beginning of ice‑sheet growth.
🧊 2. The peak of glaciation comes much later
In past cycles, the time from glacial onset to full glacial maximum is typically:
60,000–80,000 years after onset
Because ice sheets grow slowly and require persistent low summer insolation
So if onset would naturally begin in ~10,000 years, the peak of the next Ice Age would naturally occur roughly:
👉 70,000–90,000 years from now
This matches the pacing of the 100,000‑year eccentricity cycle that governs the major glacial–interglacial rhythm.
🔥 But — human climate forcing changes the picture
Every source emphasizes that anthropogenic greenhouse gases may delay or prevent the next glacial cycle:
Human emissions “have already diverted the climate from its natural course”.
Researchers warn that greenhouse gases may “delay or even alter this process in unpredictable ways”.
So the natural timeline is clear, but the real future depends on human emissions.
📌 Summary
Natural onset of next Ice Age: ~10,000 years from now
Natural peak glaciation: ~70,000–90,000 years from now
But: Human climate forcing may delay or prevent the cycle
If you want, I can show you:
a timeline of the next 100,000 years of orbital forcing,
how eccentricity, tilt, and precession combine to produce glacial peaks,
or a graph of past 800,000 years of glacial maxima for comparison.
