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Daily Changes in Tides. Tides- Caused by gravity from the Sun and the Moon pulling on and deforming large bodies of water. Historical Tide Gauge at Anchorage, Alaska. High Tide vs. Low Tide. Daily Changes in Tides
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Tides- • Caused by gravity from the Sun and the Moon pulling on and deforming large bodies of water Historical Tide Gauge at Anchorage, Alaska
High Tide vs. Low Tide Daily Changes in Tides • High tides occur on the side of Earth closest to the Moon and the side opposite the Moon. • High tides on either side of the Earth will draw water away from the areas in between, causing low tides to form there. Low tide near a dock
For most places on Earth, high tides occur every 12 hours (twice a day). • For most places on Earth, low tides also occur every 12 hours (twice a day). • Therefore, there are generally 6 hours between high and low tides.
Monthly Tidal Changes Spring Tides • Tides with maximum daily tidal range (the difference in height between high water and low water.) • Occur right after the new or full moon, about every 14 days. • When the Sun, the Earth and the Moon are in alignment, and their gravities are working together to deform oceans.
Monthly Tidal Changes Neap Tides • Tides with minimum daily tidal range • Occur right after the 1st or 3rd quarter moon, about every 14 days • Occur when the gravitational forces of the sun and the moon work against each other • Occur halfway between spring tides
Spring Tides: High Tide at noon and midnight Neap Tides: High Tide at sunrise and sunset http://earthsci.terc.edu/content/investigations/es2406/es2406page03.cfm?chapter_no=investigation
The Bay of Fundy Nova Scotia, Canada Upper picture = High tide Lower picture = Low tide (just 6 hours later)
High Tide vs. Low Tide