Time and Tide Wait for Gnomon By Roger
Time and Tide Wait for Gnomon By Roger Bailey NASS 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 Tides? – Solstices, Equinox – Date, Declination, Latitude • Monthly lunar cycle – Lunar Day ~25 hours – Phases, eclipses, obliquity – Saros cycle ~18 years
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 Tidal Sea Well Dampened Level Sensing • Proposed dual frequency harmonic sinusoidal tidal sensing correction system for a Moondial • Daily tidal variation dampened • Monthly tidal changes adjusted moondial hour angles 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 http: //www. alunatime. org/ sustainable future, reconnecting people with Proposed for UK & Australia the Moon and tides”.
Aluna Time • Wax & Wane ring – 29. 5 day lunar cycle • Moon’s position, – rise & set – Lunar time • Tidal Ebb & Flow http: //www. alunatime. org/ – Aluna’s heartbeat – 12: 25 cycle – 2: 1 synchronicity with Lunar time Simplistic tide clock concept based on two high/low per day Does not show phase, latitude, or declination effects
Tides: Vancouver Aug 16 -23 http: //waterlevels. gc. ca One Low / Day AM Solar Sun = Moon In Phase New
Sun and Moon Effects New Moon High (Spring) Tides Full Moon
Tides: Vancouver Aug 24 -31 http: //waterlevels. gc. ca New Two Weak Lows / Day Sun = Moon Out of Phase
Sun and Moon Effects Quarter Moon Low (Neap) Tides Quarter Moon
Tides: Vancouver Sept 4 -11 http: //waterlevels. gc. ca One Low / Day Full 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: //wxtide 32. 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 WXTides 32 Screen Night Daytime Now
Latitude & Season Declination Effects Summer High Tides during day? Phase shift to high tides at night! Tides lag behind gravity and water takes time to flow Full Moon
Solstice Tides: Summer Solar and Lunar Declination high Day (SUN) dominant New Sun and Moon In phase http: //waterlevels. gc. ca Negative Tides: Mid-day
Latitude & Season Declination Effects Winter Full Moon Highest Tides at night for our northern latitude Phase shift to daytime high tides! Tides lag behind gravity and water takes time to flow
Solstice Tides: Winter 2006 http: //waterlevels. gc. ca New Solar and Lunar Declination low, in phase Night (MOON) dominant Negative Tides: Mid-night
Solstice Tides: Winter 2007 http: //waterlevels. gc. ca Full Solar Declination low, Lunar high Opposite but in phase Night (MOON) dominant Negative Tides: Mid-night
Shadows and Tides • 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 Time and Tide Wait for Gnomon
Time and Tide Wait for Gnomon By Roger Bailey NASS 2006 Vancouver
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