Theodore Roosevelt’s son, Quentin Roosevelt and his friend, Roswell Pinckney. 1902.

This week, Amazon.com founder Jeff Bezos revealed the result of his mission to find the Apollo missions’ F-1 rocket thrusters, ejected from the spacecraft minutes after launch into the Atalantic Ocean, after burning 6000 pounds of rocket fuel PER SECOND to provide Neil Armstrong and company the 32 million horsepower needed to lift them into space and onward to the moon. These rockets are an incredible part of our history, and it’s nice to know Bezos will be putting them for public display.

photo by alison baskerville

So this was a thing.

I think I can only remember a few instances in my life where I’ve encountered hail, and I suppose that makes me fortunate, as being pelted with ice rocks from the sky doesn’t sound like the most appealing way to be one with mother earth.

In any case, my lack of hail experience probably comes form the fact that I’ve spent most of my life in coastal California. But I still wonder, how does hail form?

“Here’s a quarter so you can see how large my hand is, and then see how small these hailstones are.”

A bit of research (on Wikipedia) will tell us that snow forms when a cloud is below freezing, and decides to rain. That’s simple enough. Hail on the other hand is formed when there are significant updrafts within a cloud. Updrafts are typically found in thunderstorm clouds.

Our other condition for hail is supercooled water droplets. Now this is getting cool, or, interesting.

A supercooled liquid refers to the state when a liquid is below its freezing temperature, but has not formed into a solid. Ice formation requires seed crystal nuclei, which can be anything from the glass on the side of your cup to dust particles floating in the air. High in the atmosphere, there is usually a lack of seed nuclei (no, nitrogen atoms etc are not acceptable). Basically, the crystal needs something to form around. If not, you can just keep cooling down the water to lower and lower temperatures. 

Incidentally, it is also possible to superheat liquids past their boiling point, as the boiling process also requires a finite amount of energy to being the formation of air bubbles within the liquid.  Of course, both supercooling and superheating are possible by simply changing the pressure of the liquid in question, lowering or raising the freezing or boiling points, respectively.

Ruining this incredible phenomenom is the water itself! Rain that forms at the bottom of the cloud can be swept into the updraft, and it can smash into the supercooled water at speed of 5 billion miles per hour, immediately forming a layer of ice around it. Subsequently, as our little hail pellet rises, it accumulates more and more layers of frozen water, growing and growing until…

Which inevitably grows too heavy to be supported by the updraft, leading to:

AHHHH!

And the outcome of such an onslaught is:

Tragic.

Anyways, its snowing here in new york.

So just as an example of how incredible nuclear power is, any of the nine, ridiculously sized and outfitted Nimitz-class aircraft carriers in the US Navy are capable of running continuously for 20 years without refueling. With over 6000 people on board, these are literally floating cities.

That thing is enormous. Like. Jesus. Look at it compared to the international space station and a 747!

Fully loaded, it displaces 102,000 tonnes of water. Which is an awful lot of water, but sadly about the daily summer irrigation needs of New York State’s golf courses.

Of particular note in these ships are the two, GE made pressurized water nuclear reactors, driving 2 turbines and a propeller shaft each. That’s an incredible amount of energy!

The reactor heads look like robots:

Those are the control rods that can go in and out of the reactor to control the fission rate in the reactor itself. Pressurized coolant (water) flows in a contained loop into this reactor and exchanges heat with another closed loop of coolant(water/steam). The first loop is highly radioactive! The second loop of steam and water is what spins the turbine to create electricity.

Inside these reactors are simply an arrangement of fuel rods - made out of enriched uranium pellets inset in a Zinc alloy (chosen because of its low absorption cross section, meaning that it wont steal neutrons from the fission reaction). The fuel rods are submersed in water, as it works as a great moderator for the fission reaction! Neutrons can bounce off of many hydrogen atoms elastically and slow down to the right speed to be gobbled up by more uranium to spit out more neutrons and energy (heat).

Anyways. All this indicates the US naval supremacy is a long way from being challenged. So no worries there.

Apollo Theater, Harlem 1961

explore-blog:

What chalk looks like under the microscope, and other chalk curiosities from NPR’s Robert Krulwich

Alternative of the usual photo we see of these guys eating lunch.

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