Monthly Archives: January 2013

Cold Arctic Blast and the dumbo cobblestone

Cobblestone_33 degrees, Samuel Nigro

I decided to check on my neighborhood cobblestone (which I featured in One of the Greatest Insights in the History of Our Species)  on Monday, Jan. 28th to see how it fared the bone-chilling weather we had in New York City the week before, when temperatures dropped to 10˚F with strong winds and no precipitation … for days.

When I took this photo, the cold had moved on and it was a balmy 33˚F with a light dusting of snow. Today, three days later, the high is 59˚F!
This manic weather is strange, and is indirect evidence of a new climate state and a warming globe.
Yes: I am reporting on a local weather experience, and weather is not Climate.
Good: I’m glad you thought that.

But, when we look at climate: we are on an upward warming trend and there is much evidence to support the fact that the earth is entering a new climate state,
where local weather just gets weird.
Some recent and compelling
evidence is the record-breaking ice loss in the Arctic this summer.

But, let’s say you were in New York last week, and could hardly walk outside because of the cold and you were wondering:
What are you talking about “a warming planet”? What’s up with that extreme cold?

Well, the extreme cold followed by balmy weather is explained easily with our climate models and conforms to what we know about global warming,
and it has to do with a weakening jet stream.
We understand this about as well as we
understand the rise and fall of the tides … which is to say: we know what is happening.

The temperature differential between the cold Arctic air and the lower latitudes creates a stream of air, high in the atmosphere, called the jet stream that flows in, basically, a circle around the Arctic region. Normally, this air current is robust and acts like a barrier, keeping all the cold arctic air bottled up on the top of the planet.

Because of global warming, this temperature differential is decreasing, which weakens the jet stream.
As a consequence, this air current will meander in broad S-shaped patterns and reach far south,
bringing fridge cold air with it, and, because this current is weaker and slower,
it has a tendency to get stuck in its pattern.

Eventually, the jet stream may shift and move and meander, and can dip elsewhere bringing a cold arctic blast to another part of the globe.
As low as the S-curve can go, it can also creep northward, creating a very warm regional area.
This is why, in America, half of the country can have bone-chilling cold
and the other record breaking heat.

I’m glad my little broken cobblestone is still there and triggered another idea…

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Filed under Climate, Interlude, Story

my most nostalgic post so far …

Horoballs and Tsvietkova

Horoballs (note: all the spheres are tangent to the z-plane) and Anastasiia Tsvietkova

Anastasiia Tsvietkova – Hyperbolic Structures from Link Diagrams

Anastasiia Tsvietkova – Hyperbolic Structures from Link Diagrams

14 prime knots with 7 crossings

14 prime knots with 7 crossings

I lucky got the chance to go to the last Geometry and Topology Seminar at CUNY Graduate center on December 11th right before the holidays. It was a treat.

Anastasiia Tsvietkova of Louisiana State University presented her dissertation entitled Hyperbolic Structures from Link Diagrams.
Rooted in knot theory and geometric topology, she builds upon W. Thurston’s Hyperbolization Theorem,
which demonstrates that every link in a 3-sphere is

a torus link,
a satellite link
or a hyperbolic link

and these three categories are mutually exclusive. That just SOUNDS satisfying.

Her dissertation lays out an alternative way to compute the hyperbolic link in a 2-DIMENSIONAL PROJECTION.

That deserves a “WOW!”

I enjoyed the talk very much, even though much of the math was over my head.
The fact that the whole lecture only dealt with 3-dimensions made it easier.
I, at least, understood what was at stake and enjoyed following
the structure of the argument.
You can read her paper.

The bottom line:

The lecture got me to open my Knot Theory book and
revisit my drawings of hyperbolic paraboloidal shapes
from Calculus III,

because knot theory is fun and I enjoy calculus.

Hyperbolic Paraboloids from Calc III

Hyperbolic Paraboloids from Calc III

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Filed under Drawing, Featured ..., Featured Thinker, Geometry, Math