Post on 31-Dec-2015
description
1.Gravitational pull of the moon and sun
2.Centripetal force of the rotating Earth
Tides are generated by:
Tides are generated by:• the gravitational pull of the moon and sun
- moon has 2x greater gravitational pull than the sun - sun is 10 million x more massive than the
moon and is 390 times farther away
CENTRIPETAL
GRAVITATIONAL FORCE
GRAVITATIONAL & CENTRIPETAL
• Diurnal Tide: 24 hr 50 min cycle
• Semi Diurnal Tide: 12 hr 25 min cycle
• Mixed Tide: 12 hr 25 min cycle
Tidal Cycles
• High water: a water level maximum ("high tide") • Low water: a water level minimum ("low tide") • Tidal range: the difference between high and low
tide• Spring Tide: full moon and new moon (14.77 days)• Neap Tide: 1st quarter and 3rd quarter (14.77 days)
Description of tides
Intertidal zoneHigh tide
Low tide
The monthly tidal cycle(29½ days)
• About every 7 days, Earth alternates between:– Spring tide
• Alignment of Earth-Moon-Sun system (syzygy)• Lunar and solar bulges constructively interfere• Large tidal range
– Neap tide• Earth-Moon-Sun system at right angles (quadrature)• Lunar and solar bulges destructively interfere• Small tidal range
Earth-Moon-Sun positions and the monthly tidal cycle
Spring TideHighest high tide and lowest low tide
Neap TideModerate tidal range
The Bay of Fundy: Site of the world’s largest tidal range
• Tidal energy is focused by shape and shallowness of bay
• Maximum spring tidal range in Minas Basin = 17 meters (56 feet)
Alma at High Tide
Alma at Low Tide
Corals exposed to air at extreme low tide
Inquiry
1. Which has the greatest tidal effect– sun or moon?
2. Where is the greatest tidal range located?
3. Which lunar phase produces moderate tides?
4. How is a tidal bore created?