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Last update Feb 2011

   
 

Hurricanes and tornadoes

[Also see: Weather, and fog in a bottle]
The year 2005 had the most extreme hurricane season on record, with Katrina devatating New Orleans, and the National Hurrican Center running out of names, the first hurricane in history hitting Spain and Portugal, and hurricane Epsilon still active past the official end of the hurricane season. Naturally there were some questions about hurricanes.

To explain things, I made a tornado machine to show that rising air, combined with some rotation, will self-organize into a vortex, which on a small of course scale looks more like a tornado than a hurricane. The tornado in the box is 4 feet tall.

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Here is an interesting observation: look at the water in the pi pan when there is no dry ice. The tornado is still there, but you can't see it. However, the pressure in the center of the tornado where it touches the surface of the water is so low that it raises a small dimple one the surface to a height of 2-3 mm. This bump of water scoots around the surface. I made a movie of it here. In the clip, you can see the bump, and dust in and on the water slowly turning. I break up the vortex with my hand, and you see it re-establish itself quickly.
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  The second thing to explain is why hurricanes rotate in the first place, and why they go counterclockwise in the Northern Hemispere and clockwise in the Southern hemispere. For this purpose I made a flat rotating earth (hey, if Intelligent Design can be called 'science', I can claim that the earth is flat), so that I could show that a rolling ball on a rotating disk does not follow a straight ground path, but curves to the right in the Northern hemisphere. Here's how to make this turntable.

2005, Feb 2011
 

 

How does the VLA work?
The Very Large Array is located not too far from here (on Google Earth go to 34°04'32.85"N 107°36'35.83"W), so I was asked about it. Besides explaining simple parabolic mirrors, I wanted to make 2 points: 1) why are they so big, and 2) why do you chain them together?
 
I made a parabolic shape out of a piece of aluminum flashing (30x12 cm or so), and some cardboard. You can see a cork in the focal point. Off to the right out of the picture is a lamp (same one I used for the soap bubbles). You can see the light rays converging and lighting up the cork. In addition, I had a laser pointer, you can also see the reflected laser light.
All the light that fall on the mirror gets collected in the focal point, and that





 

 

Where do all the animals come from?
Time to talk about evolution, and the big picture of the history of planet earth. I have this poster (more here)
 

 

Any suggestions, comments, greetings are greatly appreciated.
Just click here and type away!
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Last update Feb 2011 - HvH
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