[time-nuts] Q/noise of Earth as an oscillator

[Hal Murray]

glennmaillist at bellsouth.net said:
> In navigation we used the earth rate of 15.04 degrees per hour. This was
> treated as a 'constant' even though it varied with wind, waves  on the ocean
> and other things affecting the instantaneous rotational  speed of the earth.

Were the wind and waves and whatever significant?   Measurable?

> How does this factor into leap seconds, or, does it?

Leap seconds are necessary to correct for the unpredictable things like waves 
and earthquakes and ice caps melting.

There is also tidal friction which is slowing down the rate of rotation.  So 
even if the wind and friends were insignificant we would need to adjust the 
clocks occasionally.


> We accept that the day is 24 hours long, this would be for a earth
> rotational speed of 15.0 degrees per hour.

The 0.04 is the difference between solar (sun) and sidereal (stars) time.

During a year, the earth goes around the sun.  If your clock runs on solar 
time but you are looking at the stars, that adds one more rotation per year.  
That's 360/365 degrees per day or 0.04 degrees per hour.


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