I've been doing more research trying to find what causes the length of Earth's day to change every day. This change is called the Length Of Day Delta (LODD) and it seems it's as mysterious to scientists as it is to me.
Previous Posts In This Series
More On Water Vapor, Length Of Day Delta Correlation
Stunning New Climate Correlation
What Causes The LODD?
That's question I wanted to answer as I googled around the net looking for papers or articles about the LODD. But unfortunately, it seems there are almost as many different options on what causes the LODD as there are papers and articles about the LODD. According to one web site, LODD is caused by Global Warming and will make days get shorter. According to another article on the same web site, LODD is caused by Global Warming and will make days get longer.
NASA says the annual changes in length of day are caused by the atmosphere. But someone else at NASA says its the atmosphere, oceans, and land, which narrows it down to everything on the planet. That first NASA article says decade-scale changes are due to changes in the Earth's core.
So to me, it sounds like science doesn't have a solid answer on what causes the LODD, though it may have several good candidates. I told a reader, Charles, that I would look into calculating changes in the LODD based on changes in water vapor. But I think I'm going to have to forgo that promise on the grounds that if professional scientists studying this full time can't provide a solid answer, original research by a software engineer isn't going to settle things either.
But that's ok. I still have the correlations between LODD and other climate factors. I don't need to know causes to examine correlations.
Example Of Another LODD Correlation
In a previous post I showed solar ephemeris data overlaid with LODD data. That graph is reproduced here. We can see from this graph that the monthly scale changes in LODD have a good reverse correlation to the monthly scale changes in the solar ephemeris.
Solar ephemeris data is based on the Earth orbiting the sun. And in this case I think it's safe to say this orbit is causing, directly or indirectly, the monthly changes in the LODD.
That still leaves the causes of the LODD changes over a decade as unknown, and it still leaves us with no explanation as to why there seems to be two different correlations between LODD and water vapor on the decade scale.
LODD is caused by Global Warming and will make days get longer
NASA: Annual changes in length of day are caused by the atmosphere
NASA: Annual changes in length of day are caused by the atmosphere, oceans, and land