I'm writing this post from a ScribeFire window in FireFox. I'll be setting this up on all my machines this weekend. Now whenever I find anything remotely interesting (and that won't get me in trouble), I can post it directly.
If you blog, you should check it out.
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So, I used to take time off on Fridays and show movie trailers and clips in class. These were known as Freaky Fridays. Unfortunately, Freaky Fridays became all Freaky Friday, all the time. Followed by requests for Manic Mondays, Tubular Tuesdays, Wacky Wednesdays, and Trippin' Thursdays. So, no more Freaky Fridays. Blame the alumni.
But I guess I can do that here.
So, for your edification, I present the following:
1) Boom de Yada!
2) Since we're talking about electricity in class, here's a tremendous video of lightning in super-slow motion:
Remember that air is an insulator. When a spark jumps from your finger to the doorknob, or lightning jumps from cloud to ground, the electrons have to punch their way through the air, in order to get the air out of the way to allow conductivity through the vacuum. In the first seconds of the video, you can see wide-ranging branching as the initial electrical surges from the cloud attempt to find the path of least resistance through the air to the ground by working their way through the thin eddies in the air that they can find or create. Once a streamer finds its way to the ground, the path from the cloud to the ground becomes the primary (only) conductive pathway, and flashes through the length of the path are seen throughout the rest of the video. Note that the rest of the branches flicker once or twice as electricity flashes down the still-open partial pathways, but most of the flow is through the primary path and the rest of the branches are quickly abandoned.
The conductive pathway is a good vacuum - remember, no vacuum is perfect - but the vacuum is continually compressed and invaded by the higher-pressure atmosphere around it. As the electricity pushes the air out of the way in the first branching, the air is excited by the electrical charge and emits light. Those are the flashes. As the electrical charges pass a given point in the pathway, the pathway contracts from the outside pressure, and the next charge has to push the air back out of the way, exciting the molecules again. This is what gives lightning its flickering nature. In addition the air is heated to tens of thousands of degrees Fahrenheit, as much as 50,000 deg F. This superheated air collides with the colder air outside the pathway and sheds its energy in the collisions, creating a shockwave through the air we hear as thunder. The rippling nature of thunder comes from the successive shockwaves of each electrical pulse re-evacuating the conductive pathway, each of which generates a "crackle."
3) A primer on the Somali pirates. Why? Because there's information here I found interesting, and - PIRATES!
And that'll do for now. Check your mail later for the Gas Law Review key.
CS
If you blog, you should check it out.
----------
So, I used to take time off on Fridays and show movie trailers and clips in class. These were known as Freaky Fridays. Unfortunately, Freaky Fridays became all Freaky Friday, all the time. Followed by requests for Manic Mondays, Tubular Tuesdays, Wacky Wednesdays, and Trippin' Thursdays. So, no more Freaky Fridays. Blame the alumni.
But I guess I can do that here.
So, for your edification, I present the following:
1) Boom de Yada!
2) Since we're talking about electricity in class, here's a tremendous video of lightning in super-slow motion:
Remember that air is an insulator. When a spark jumps from your finger to the doorknob, or lightning jumps from cloud to ground, the electrons have to punch their way through the air, in order to get the air out of the way to allow conductivity through the vacuum. In the first seconds of the video, you can see wide-ranging branching as the initial electrical surges from the cloud attempt to find the path of least resistance through the air to the ground by working their way through the thin eddies in the air that they can find or create. Once a streamer finds its way to the ground, the path from the cloud to the ground becomes the primary (only) conductive pathway, and flashes through the length of the path are seen throughout the rest of the video. Note that the rest of the branches flicker once or twice as electricity flashes down the still-open partial pathways, but most of the flow is through the primary path and the rest of the branches are quickly abandoned.
The conductive pathway is a good vacuum - remember, no vacuum is perfect - but the vacuum is continually compressed and invaded by the higher-pressure atmosphere around it. As the electricity pushes the air out of the way in the first branching, the air is excited by the electrical charge and emits light. Those are the flashes. As the electrical charges pass a given point in the pathway, the pathway contracts from the outside pressure, and the next charge has to push the air back out of the way, exciting the molecules again. This is what gives lightning its flickering nature. In addition the air is heated to tens of thousands of degrees Fahrenheit, as much as 50,000 deg F. This superheated air collides with the colder air outside the pathway and sheds its energy in the collisions, creating a shockwave through the air we hear as thunder. The rippling nature of thunder comes from the successive shockwaves of each electrical pulse re-evacuating the conductive pathway, each of which generates a "crackle."
3) A primer on the Somali pirates. Why? Because there's information here I found interesting, and - PIRATES!
And that'll do for now. Check your mail later for the Gas Law Review key.
CS
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