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Re: [Phys-L] Physics, seasons, and temperature.

On 3/24/21 9:31 AM, John Sohl via Phys-l wrote in part:

One result of this is that the oceans store a vast amount of thermal

Yes, that connects to what I was saying about RC low-pass filters.
Locations that are downwind of a large body of water (including
large lakes as well as oceans) see temperatures that are more
strongly filtered. The variations are smaller and come later
in the year. Slower to warm up in the spring, and slower to
cool down in the fall.

In the typical discussion of AC circuits, they leave the component
values alone and vary the frequency. In the present discussion,
the frequency is the same everywhere (ω = 2π radians per year) but
the capacitance is different from place to place. Water has much
more heat capacity than dry land. The calculation is simple and
the graph looks the same, because the relevant abscissa is ωRC.
So changing C isn't much different from changing ω.

The plot of amplitude and phase is called a Bode plot. In case
you don't have it memorized, the plot for an RC low pass filter
is on page 8 here:

Climate is in the regime where both amplitude and phase are fairly
steep functions of ωRC.


There is much additional physics on top of that. The ocean doesn't
just store energy; it also /transports/ huge amounts of energy.
That is a big deal for western Europe, where the climate is very
strongly influenced by the Gulf Stream, which transports tropical
water by a remarkably direct route. Western Europe would be very
much chiller without the Gulf Stream. This can be quantified, but
here is a more graphic presentation of what I mean:

That's a map of Europe, superimposed with cities at the same latitude,
dragged in from places that aren't warmed by the Gulf Stream. You
can see that famously balmy places that are pretty far south by
European standards have latitudes that would be considered unbalmy
and pretty far north elsewhere.


The zinger is that the Gulf Stream is being weakened by climate change.
Many models predict there will be a /tipping point/ where it shuts
down completely or changes course. This would be exceedingly bad news
for western Europe.

There are many articles on this subject, which you can find by googling.
Here is one example: