Time and Tide Wait for Gnomon By Roger Bailey NASS 2006 Vancouver

Time and TideWait for Gnomon

ByRoger BaileyNASS 2006 Vancouver

Newcomer’s Tide Questions

• Tides are caused by the gravitational attraction of the sun and moon but….

• Why are there sometimes two tides a day?• Why are tides really high and low twice a

month?• Why are the really low tides in the middle of the

night in the winter and midday in summer?• Is there better information available than the

newspaper tide tables?• Can sundial science answer the “Whys”

WHY?

Sundial Science: What Can You Learn from a Stick & Shadow

• Daily cycle of sun– Sunrise, sunset, noon– Time, Hours, Longitude

• Yearly cycle of Sun– Solstices, Equinox– Date, Declination,

Latitude

• Monthly lunar cycle– Lunar Day ~25 hours– Phases, eclipses,

obliquity – Saros cycle ~18 years

Tides?

Moon Dials

• A sundial can be used as a moondial– When the moon is full– 12 noon for the full moon is 12 midnight– Adding ~ 48 minutes for each day past full– Subtracting ~48 minutes for each day

before full moon (actually 48 +/-7)• Full moon declination ~ opposite sun

+/-• Exactly opposite for lunar eclipse• Exactly equal for solar eclipse

Moon Madness: SML 1999

• Proposed dual frequency harmonic sinusoidal tidal sensing correction system for a Moondial

• Daily tidal variation dampened

• Monthly tidal changes adjusted moondial hour angles

WellDampenedLevel Sensing

Tidal Sea

Patents Applied for: R. Bailey, R. Goldberg, H. Robinson

Aluna: Tidal Powered Moon Clock

• “Imagine a breathtaking sculpture that combines cutting edge design and technology with an ancient knowledge of the Earth's natural rhythms.”

• “A monumental timepiece for the planet, a beacon for a sustainable future, reconnecting people with the Moon and tides”.

http://www.alunatime.org/

Proposed for UK & Australia

Aluna Time

• Wax & Wane ring – 29.5 day lunar cycle

• Moon’s position, – rise & set– Lunar time

• Tidal Ebb & Flow– Aluna’s heartbeat– 12:25 cycle– 2:1 synchronicity with

Lunar time http://www.alunatime.org/

Simplistic tide clock concept based on two high/low per dayDoes not show phase, latitude, or declination effects

Tides: Vancouver Aug 16-23

NewSun = Moon In Phase

One Low / Day AM Solar

http://waterlevels.gc.ca

High (Spring) Tides

Sun and Moon Effects

New Moon

Full Moon

Tides: Vancouver Aug 24-31

NewSun = MoonOut of Phase

Two WeakLows / Day


Sun and Moon Effects

Quarter Moon

Quarter Moon

Low (Neap) Tides

Tides: Vancouver Sept 4-11

FullOne Low / Day Two Lows / Day


Harmonic Analysis: Equation of Time

• Sum of periodic changes to solar day

• Sum of obliquity and eccentricity effects

• Obliquity: – tilt of earths axis

• Eccentricity:– elliptical orbit

http://www.analemma.com

Harmonic Analysis: Tides

• Sum of waves of different amplitudes and periods

– Sun: 24 hr day. 12 hr tides, Noon & Midnight 1 year, Solstice, Equinox, Declination

– Moon: 24:48 hr day, 12.5 hr tides, monthly 29.5 day orbit, Phases, Declination Eclipses, Ecliptic, obliquity, Saros

– RC resonance: velocity, volume, frequency – Phase shifts,Time delays, Shallow vs deep,

funnel effects

Tide Tables: Hydrographic Surveys

• Click on http://waterlevels.gc.ca and follow the links, maps etc for your location

• US Data: NOAA • National Oceanographic and Atmospheric

Agency http://tidesonline.nos.noaa.gov/geographic.html

• UK Data: UKHO Admiralty Easy Tide http://easytide.ukho.gov.uk/ $

NOAA Tide Graphic

Computing Tides on your PC

• Windows Tide and Current prediction program http://wxtide32.com/

• Install the free shareware on your PC• Set up your preferences like your location• It also includes locations for currents• Based on NOAA Harmonic Analysis

models and factors from world wide public sources

• Problems with use of UK harmonic factors and UKHO copyrights

Typical WXTides32 Screen

Now

DaytimeNight

High Tides during day?

Full Moon

Latitude & Season Declination Effects

Summer

Phase shift to high tides at night!Tides lag behind gravity and water takes time to flow

Solstice Tides: Summer

Negative Tides: Mid-day

New

Solar and Lunar Declination highDay (SUN) dominant

Sun and MoonIn phase


Latitude & Season Declination Effects

Highest Tides at night for our northern latitude

Full Moon Winter

Phase shift to daytime high tides!Tides lag behind gravity and water takes time to flow

Solstice Tides: Winter 2006

NewSolar and LunarDeclination low, in phaseNight (MOON) dominant

Negative Tides: Mid-night


Solstice Tides: Winter 2007

Solar Declination low, Lunar highOpposite but in phaseNight (MOON) dominant

Negative Tides: Mid-night

Full


Time and Tide Wait for Gnomon

• Sundial (Stick and Shadow) science is useful for understanding tides

• Tides are caused by the harmonics of solar and lunar cycles

• Sundials show solar cycles, time of day, day of year, seasons and harmonics

• Moondials show lunar cycles• Latitude and declination are important

for shadows and tides

Shadows and Tides

Time and TideWait for Gnomon

ByRoger BaileyNASS 2006 Vancouver

Documents

Time and Tide Wait for Gnomon By Roger Bailey NASS 2006 Vancouver