Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 08/08/2016 18:53:02

Title: If the Earth's rotation is slowing down was it windier in the distant past?
Post by: thedoc on 08/08/2016 18:53:02

Dr. Arv Edgeworth asked the Naked Scientists:
   I have a question for you.  I have contacted the scientists at NASA, and the National Weather Service, and so far have had no response.  I was told that if you spin a planet faster you increase the wind speed.  Jupiter and Saturn were given as evidences of that.  Since we know the earth is slowing down in its rotation, and we know the rate at which it is slowing down, then if we went backwards in time at that rate, would it have an affect on the wind speed on earth?  If we went back far enough in time would it possibly make earth uninhabitable?
 
Dorian Abbot of the University of Chicago is quoted as saying that new research has revealed that the rate at which a planet spins is instrumental in its ability to support life.  He also said it affects the winds.  Do you have any information on this?  Thank you for your time.
Sincerely,
Dr. Arv Edgeworth
What do you think?

Title: Re: If the Earth's rotation is slowing down was it windier in the distant past?
Post by: Tim the Plumber on 08/08/2016 22:47:39

How would you go backwards in time?

Title: Re: If the Earth's rotation is slowing down was it windier in the distant past?
Post by: Blame on 08/08/2016 23:09:06

Doubt it. Weather is complex but the main factors are likely to be energy input (solar powered for earth but not the gas giants which are internally powered) and the friction of surface features. The sun is slowly powering up so maybe there was lower wind speed back then.

The massive wind speeds of the gas giants have been attributed to low friction.

Title: Re: If the Earth's rotation is slowing down was it windier in the distant past?
Post by: evan_au on 08/08/2016 23:18:25

Winds are driven to a large extent by temperature differences induced by the Sun. So if the Sun were hotter in the past, or greenhouse gases were more plentiful in the past, we might see stronger winds.

The direction of wind is driven by the Coriolis force - if the Earth were rotating more rapidly, the Coriolis force would be stronger, and the direction of winds would be bent more tightly into circles by the Earth's rotation. I guess this could produce faster winds without a change in temperature.

You have to look a long way back in time to see much of a change in length of Earth's day, currently about 2.3ms per century. This is due to tidal drag causing recession of the Moon (https://en.wikipedia.org/wiki/Lunar_distance_(astronomy)#Tidal_dissipation).

When the Moon was much closer, tides would have been enormous and most life would have lived in the sea, where it is shielded to some extend from the winds.

Title: Re: If the Earth's rotation is slowing down was it windier in the distant past?
Post by: CPT ArkAngel on 09/08/2016 08:21:15

Evan explanation is correct. If the rotation of the earth is faster (and all other factors are the same like the average temperature), there would stronger wind on average. Tornadoes would be more frequent and stronger. But like Evan said, the difference of Earth's rotation rate in the past is only slightly faster so probably other factors variations in the past were more significant than the faster rotation of the earth.