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

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.

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.

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.

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 FundyNova Scotia, Canada

Upper picture = High tide

Lower picture = Low tide (just 6 hours later)

                                        

Miajima Island, Japan