Daily Reading Notes

Tides

Day 8

Posted on 2019-03-13

The tides don’t follow the moon perfectly. They can vary by plus or minus 7 days. The big deviation from expected behavior is due to friction which has many more effects.

The moon causes a bulge so big it would been an ocean over 6,000 miles deep to travel freely. But the ocean is only 3,000 miles on average, so the waves drag almost the entire time. The drag they experience in the middle of the ocean is nothing compared to when they hit the continental plates. These shallow areas around the continents cause the tide to rise up from 2 feet in the open ocean to over 60 feet in some coasts. This effect is also responsible for the large waves we see at the beach.

The friction force experienced by the tides is powerful enough to slow down the rotation of the earth. This is why we need to account for a leap second every few year. The react to the tides from the ocean floor even effect the moon. Slowly the moon is pushing itself back and lessening its effect on the earth’s oceans.

Tides