Thread: How do tides work?

Interestingly, it's not all that difficult to calculate the effect of atmospheric pressure on tides. On a standard day, 1 ATM = 101.3 kPa = 14.7 lb per sq in = 1,013.2501 millibars = 29.9212583 inches of mercury (Hg). Also equivalent to 1 ATM is 30 feet of seawater.

At second landfall, near Buras-Triumph, Louisiana, Katrina's minimum pressure measured 27.17 in Hg. That's 90.81% of standard day, which means it's also 9.19% below std day. To compute the effect on mean sea level, one merely need multiple 30 feet by 9.19%, which yields 2.76 feet.

Needless to day, the drop in pressure only accounts for about 13% of the roughly 20 foot storm surge that hit the levees and Slidell, the first town north of New Orleans. Slidell's main street is 16 feet above mean sea level, yet it was 5 feet underwater, for a total surge of 21 feet above mean sea level.

What accounted for the remaining 18 feet aka 87% i.e. 18 ft of storm surge? Primarily, two things: Large waves rapidly washing inland, while flowing back to sea slowly due to the very nearly flat land, and the strong northerly surface currents generated by sustained 125 kt winds. Combined with the nearly flat land and heavy rainfall, the storm flooded its way inland for many miles.

Originally Posted by TaoZero5

There's a place called Pugwash???

Of cousre there is...where did you think they washed pugs....

Mugaliens has provided a great deal of information regarding hurricane Katrina and why she did so much damage.. and that tidal ocean movement and atmospheric pressure do play a role.. but wind speed and direction far out strip other forces.. thanks Mug's... and now back to...

How do tides work ?

Well a basic understanding is to consider that the oceans are pulled by the sun and a little more so by the moons field of gravity effect...

while planet earth is also distorted by those same forces. They are measurable...

Because the land masses interrupt the motion of the gravity effect. The hight of the tide changes as the planet rotates...

I am not the mathematician that can provide for you the details of tidal timing..

I have been involved in a boating venture but relied on published charts for tide timing... I think its a 13 hour cycle...

Originally Posted by David E. Eaton Sr.

Of cousre there is...where did you think they washed pugs....

I thought it was a typo for Rugwash...