Cycles, Explained — Natural Cycles Almanac (experiment)

1 · Many clocks at once

Every rhythm is a ring

Think of each natural cycle as a clock with one hand. Fast clocks sit low; slow clocks sit high. The dark bead on each ring shows where that rhythm is right now. When a bead crosses the front line, that rhythm is at its high point: a full moon, the longest day, a solar peak.

Key

Sky rhythms: day, moon, year
The sun's 11-year cycle
Life: periodical cicadas ()
The moon's 18.6-year tilt cycle
The Pacific (El Niño / La Niña): not a clock, so its ring is coloured ochre (El Niño) or plum (La Niña) by the real reading
Bead = where the rhythm is · front line = high point

Travel in time

These rings are idealised: real cycles stretch and shrink a little. Press “1 year / sec” and watch the day and moon rings blur while the sun and cicada rings barely move. That difference in speed is why some patterns take a lifetime to see.

Well established The timing of the day, moon, year, sun and cicada broods is measured and predictable.

2 · How do we know a rhythm is real?

Wrap the years around a circle

Here's a trick scientists use, made visible. Take a long record, one dot per year, and wind it around a post like thread. Each turn of the thread is one guess at the rhythm's length. Big values sit farther out and are darker.

If the guess is right, the big years land on the same side, turn after turn, and the dots line up into a dark column. If the guess is wrong, they scatter all the way round.

Record Guess the rhythm: 11.0 years

Line-up strength:

Key

Dark, far out = a big year · pale, close in = a small year
Up the post = later years
Arrow = where the big years point; longer arrow = stronger line-up
Little chart = line-up strength for every guess. The tallest bump is the rhythm.

Try “Shuffle”. It keeps every value but mixes up the years. A real rhythm vanishes, and the strength that's left is what pure chance gives. This is the idea behind the “wavelet” analysis in the full almanac.

Well established The sunspot rhythm ( years) and the goshawk rhythm ( years) both pass this kind of test.

3 · A lake's winters, coiled

170 years of ice on Lake Mendota

People in Madison have written down the day Lake Mendota froze and the day it opened every winter since . Here every year is one turn of a spring, from the oldest at the bottom to the newest at the top. The thick, bright part of each turn is the time the lake was frozen.

Look up the spring: the frozen arcs get shorter. The lake now averages about days of ice, down from about in the 1800s.

Key

One turn = one year. The brown “Jan 1” label marks New Year's Day; months are labelled round the base.
Thick arc = lake frozen (freeze-up → ice-out)
Arc colour = what the Pacific was doing that winter: El Niño · La Niña · neutral or before records (1950)
Thin line = open water

Notice how the ochre (El Niño) arcs tend to be a bit shorter: they average days against for La Niña winters. That's a real tendency, but a loose one, and plenty of El Niño winters still froze long.

Well established Shorter ice seasons: measured directly, and seen on lakes worldwide. Likely El Niño trims the season, by roughly a week on average here.

4 · The Pacific connection

Does a warm Pacific mean less Great Lakes ice?

El Niño and La Niña are swings in the temperature of the tropical Pacific Ocean. They bend the jet stream, the river of wind that steers storms and cold air across North America. Top row: the Pacific each winter. Bottom row: how much of the Great Lakes froze that winter.

Key

Top bars: up = El Niño (warm Pacific) · down = La Niña (cool)
Bottom bars: height = share of the Great Lakes frozen at the winter's peak; colour = that winter's Pacific state
Glass sheet = a typical winter (% frozen)

What “correlation” means

A correlation measures how often two things move together, from −1 (always opposite) through 0 (no link) to +1 (always together). Here it is for the whole Great Lakes: a faint opposite link. In El Niño winters, ice was below typical. That's not much better than a coin toss. On little Lake Mendota the link is clearer ().

Possible conclusion: the Pacific nudges our winters but doesn't decide them. The Arctic's own swings and plain cold spells often matter more for the big lakes.

Likely A real but modest influence; scientists find it's strongest in very strong El Niño years.

5 · The sun's eleven-year breath

Storms on the sun, lights in our sky

The sun gets busier and calmer about every 11 years, and we count sunspots to track it. Around the sun are all 25 counted cycles since 1755, as arches. Taller arches were stronger cycles. The bead on the newest arch is where we are now: just past the peak of Cycle 25.

Near and just after a peak, the sun throws out more storms. When a big one reaches Earth, the aurora (northern lights) can be seen from the Great Lakes. The curtains above are stronger when recent years have had more of those storms.

Key

Arch = one solar cycle; height = how many sunspots at its peak
Bead = today, on Cycle 25
Curtains = recent aurora-strength storms

What next: the next few years, on the falling side of the cycle, are still good for aurora sightings. Big storms often come after the peak.

Well established Sun → storms → aurora. Not supported here The popular idea that solar lows bring cold winters didn't hold up in our test (view 11).

6 · Moons that drift

Twelve moons, or thirteen?

Each ring is one year, with January at the front, stacked from at the bottom upward. Each ball is a full moon (dark = supermoon). Follow the thread from moon to moon: it slides about 11 days earlier each year, because twelve moon-months are a little shorter than a year. Every two or three years the drift leaves room for a 13th full moon; those rings glow.

Key

Ring = a year (front = January) · ball = a full moon · big ball = supermoon (moon closest to Earth)
Thick coloured ring = a year with 13 full moons
Thread = moon-to-moon order, showing the drift

How nations name the moons

Many nations around the Great Lakes publish their own moon calendars, and each is its own. Some tie each name to a calendar month (like the Ojibwe calendar published by GLIFWC). Others count real moons from a season, such as the Menominee, whose year begins with the sugaring moon. Those calendars handle the 13th moon differently. The names describe things you can watch for: sap running, strawberries, wild rice, ice forming.

Names as published by each nation, with links in the full almanac. Spellings and months differ between communities.

Well established Moon timing is exact astronomy. Traditional knowledge Moon names are each nation's own record of the seasons.

7 · Life on schedule

The birds' year in Wisconsin

The year runs around this ring like a clock, with January at the front. Each circle of little towers is one of bird species; a taller tower means more of that species around that week. Watch the two waves: one in spring (May) and one in fall (September), as birds pass through.

Key

Around the ring = weeks of the year (front = January)
Each circle of towers = one species (point to see which)
Taller and darker = more of that species that week (each scaled to its own peak)
Pointer = this week

Influence: many songbirds time their journeys by day length, which never changes from year to year, while leaves and insects follow temperature, which does. As springs warm, the food can peak before the birds arrive. Scientists call that a “mismatch.”

Well established Migration timing (eBird, millions of checklists). This shows a typical year, not one particular year.

8 · Hunters and hunted

Wolves and moose on Isle Royale

On an island in Lake Superior, wolves and moose have been counted every winter since 1959. This line is their story. Moving right means more moose, moving up means more wolves, and the line moves toward you as the years pass.

When the line curls around, that's a predator–prey cycle: plenty of moose → wolves increase → moose fall → wolves fall → moose recover. The wolves trail the moose by a few years.

Key

Right = more moose · up = more wolves · toward you = later years
Colour runs from plum (1959) to dark brown (recent)
Point at the line for the year and counts

The island's story also has breaks: a disease in wolves in the 1980s, a near-collapse of the wolves by 2018, and new wolves brought in from 2018 on. Real cycles get interrupted.

Well established Wolves and moose drive each other here. The exact rhythm isn't steady enough to forecast.

9 · The web of influences

What affects what

Every ball is something in nature; every line with moving sparks is an influence, flowing from cause to effect. Layers go from the sky at the top, through ocean and air, to lakes and weather, down to living things.

Key: how sure is each link?

Well established: a known mechanism plus the data agree
Likely: published studies show it; details still debated
Unproven: a saying or idea that hasn't held up well
Traditional knowledge: a nation's moon names marking a season
Sparks move from cause to effect. Faster, darker sparks = stronger evidence.

Pick a chain to follow, or click any ball to light up everything that affects it and everything it affects:

Well established to Unproven: each line keeps its own rating. Correlation alone never earns “well established”; it takes a mechanism too.

10 · What lines up next

The next two years, month by month

Each column is a month, starting now. Each stacked layer is one rhythm, and its colour gets stronger the closer that rhythm is to a high point (or a low one). Tall columns are months when several rhythms line up.

Key

Left → right = the next 24 months
Layers, bottom to top:
Stronger colour = that rhythm is near an extreme
Glass column height = overall “line-up” score, weighted toward rhythms with well-established effects

Strongest line-ups ahead

Important: rhythms lining up is interesting, but it's not a prediction that something special will happen. Most line-ups are coincidences in timing. The web of influences (view 9) says which ones actually push on each other.

Well established The dates are exact for sky events; bird and climate layers are typical patterns.

11 · Testing the sayings

Old sayings meet 75 years of records

Each pillar is one claim about winter, from folk sayings to science. We checked every year the claim applied: did winter go the way the claim said? The glass sheet is the coin-flip line at 50%. A claim needs to stand well above it, again and again, to beat luck.

Key

Pillar height = how often winter went the claimed way
Glass sheet = 50%, what a coin flip would score
Colour = where the claim comes from: science · folk saying · fringe idea

Possible conclusion: most sayings land near the coin-flip line. Even the science-based ones are only modestly better than chance in any single winter. Nature's signals are real, but noisy.

Unproven None of these passed the strict test that guards against lucky streaks. Some (like “La Niña means snow”) lean the right way.

12 · The coming winter

Winter : the odds

Forecasts for a whole season can't say “it will be cold on January 12”. They give odds, like a weighted die with three faces: below normal, near normal, above normal. A fair die would be one-third each. The taller the column, the more the die is weighted toward that face.

Key

the colder side (colder, more ice, more snow) · near normal · the milder side (warmer, less ice, less snow), compared with 1991–2020
Thermometer on the left = the Pacific's projected temperature this winter
Glass sheet = 33%, the fair-die line
Groups, left to right:

We write every forecast down before the winter starts and score it afterwards, misses included. The full almanac keeps that record.

Likely Seasonal odds have modest skill: useful for leaning, not for planning a specific day.

Words to know

Cycle (rhythm): Something that rises and falls again and again, like the moon or the seasons.
Period: How long one full cycle takes: 29.5 days for the moon, about 11 years for the sun.
Correlation: How often two things move together, from −1 (opposite) through 0 (unrelated) to +1 (together). It shows a link, not a cause.
Influence (cause): One thing actually pushing on another, with a known way it happens (a mechanism).
Lag: The delay between a cause and its effect, like acorns one fall leading to more ticks two years later.
Anomaly: How far a value is from normal: a winter 2 °C warmer than usual has a +2 °C anomaly.
El Niño / La Niña: Warm and cool swings of the tropical Pacific Ocean every 2–7 years that reshape weather far away.
Odds (probability): How likely something is. 50% is a coin flip; 33% is one face of a three-sided die.
Chance test: Checking whether a pattern could be luck. With hundreds of comparisons, some will look impressive by chance, so we raise the bar.
Traditional knowledge: Knowledge a nation keeps and shares about its land and seasons, here as the moon calendars each nation publishes.

For every chart, number and source, see the Natural Cycles Almanac or dive deeper into the data. 1333 Covenant home ↗

Data: NOAA, NASA/SILSO, USA National Phenology Network, eBird (Cornell Lab), HawkCount, USDA Forest Service, Wisconsin State Climatology Office, Isle Royale project, and the published calendars of the Ojibwe (GLIFWC), Citizen Potawatomi, Menominee and Haudenosaunee nations.