Northeasters, Convection Heating, Thunderstorms, Electricity, Electric Charge, Capacitors, Lightning and Lightning Rods

Posted by PITHOCRATES - February 8th, 2012

Technology 101

A Couple of Centuries ago when a Winter Storm Approached we Stocked Up on Wood for our Cast-Iron Heating Stoves

A study of prevailing weather conditions can predict tomorrow’s weather.  Once you’ve learned some basic weather phenomenon.  Weather generally moves from west to east.  Where cold fronts meet warm fronts we can get storms, tornados, rain, sleet, snow, etc.  And if a swirling northeaster buries a town under snow people in a town northeast of this town can expect the same.  Even though the winds are blowing in the opposite direction.

Today in the worst of winter’s weather we can stay warm and snug at work.  And at home.  Amazing when you consider some of our work places have a lot of exterior glass walls.  Glass curtain walls.  Which really transmit the cold.  Of course, even these rooms can be toasty rooms.  Ever wonder how?  Take a look at the floor under the window.  What do you see?  Fin-tube radiation heating registers.  Copper pipes with metal fins soldered to them.  We pump heating hot water through the copper pipe.  And when we do these fin-tube radiators heat the air as it moves through those fins.  As air heats it expands and gets thinner.  Becoming lighter than the cold air.  And rises.  As it moves up it pulls the cold air below through those heated fins.  Heating the cold air.  Where it, too, expands and gets thinner.  And rises.  Creating a heating convection current.  Heating the room.  And the window.  By washing it with warm air.  All without using a fan to move the air.  Heating units that do have fans and move the air are more for circulating the air to prevent the build of carbon dioxide (produced as we breathe).  While fin-tube heating does the lion’s share of heating our buildings.

So when they predict a winter storm we really don’t worry much about staying warm inside.  Of course, it wasn’t always like this.  A couple of centuries ago when we saw a winter storm was moving our way we made sure we had enough wood available.  To burn in our cast-iron heating stoves.  Where we burned our heating fuel in the room we heated.  And vented the products of combustion out through the chimney.  A big difference to using heating hot water and fin-tube radiators.  But the same principle nonetheless.  These wood-burners heated the cold air and created a heating convection current.  Just like those fin-tube radiators.

During Thunderstorms Clouds act like Charging and Discharging Capacitors

In the summertime when a cold front runs into a warm front it often generates some big thunderstorms.  And some dangerous lightning.  Which has started many building fires throughout history.  Especially churches with tall spires.  Which seemed to be magnets for lightning.  Which they were.  In a way.  Because thunder storms are electrical storms.  Which is why we have lightning.  But first a little about electricity.

Electricity flows between a positive and a negative charge.  The greater the difference in charges the greater the flow of electricity.  A battery can store a charge.  A battery has both a positive (plus) and a negative (minus) terminal.  You charge a battery by applying a voltage across these terminals.  The higher the voltage and/or the longer the charge the more energy is stored in the battery.  When we connect a light to a battery it completes the circuit between the plus and minus terminals.  And electricity flows through the light and illuminates it.  The light will stay lit until the battery runs out of charge.  Or until we open the circuit.  Depending on the voltage or amount of stored charge you may see sparks at the point where the circuit opens or closes.  The charge being strong enough to jump a small air gap just before the circuit is closed.  Or just after it opens.

A capacitor can also hold a charge.  What we used to call a condenser.  Which is a couple of plates separated by an insulator.  When we apply a voltage across the plus and minus terminals the plates charge.  The insulator keeps them from discharging internally.  The bigger the capacitor (i.e., the bigger the surface area of the plates) the bigger the stored charge.  After you charge a capacitor it will hold that charge.  It will dissipate slowly over time.  Or quickly if you short out the plus and minus terminals.  And if you discharge a capacitor quickly you’re going to see some sparking.  As the charge jumps the air gap just before the circuit is closed.  The bigger the capacitor the bigger the sparking.  Funny story.  I saw a kid cutting out the capacitor from an old television set.  The kind your parents had.  With a big glass cathode ray picture tube that used high voltage to move a scanning electron beam to excite (i.e., make glow) the phosphorous coating on the inside of the picture tube.  High voltage and a capacitor mean only one thing.  A very BIG stored charge.  No one turned on that TV for a long time.  But that capacitor held its charge.  As this kid quickly learned.  The hard way.  As he cut the wire going to the plus terminal his un-insulated side cutters touched the metal of the TV chassis.  Which was, of course, grounded.  So you had the plus terminal of a highly charged capacitor coming into contact with the minus terminal of said capacitor (via the grounded TV chassis).  It was like the Fourth of July in the back of that TV.  Threw that poor kid back on his butt.  Funny.  We all had a good laugh.  He was no worse for wear.  Except, perhaps, needing a new pair of undershorts.

All right, back to those electrical storms.  And lightning.  In a nutshell, those ugly black storm clouds are like capacitors.  As the atmosphere churns up these warm and cold weather fronts as they collide something happens.  They charge.  Like a capacitor.  With one plate being on the top of the cloud.  And the other plate being on the bottom of the cloud.  As the charge grows on the bottom of the cloud it induces an opposite charge in the ground below.  The old ‘opposites attract’.  So if a larger and larger minus charge is building up in the bottom of the cloud it attracts (i.e., induces) a larger and larger plus charge on the surface of the earth beneath the cloud.  Until the charges grow so great that they jump the air gap.  But this is no capacitor discharging.  The amount of energy in a lightning strike is so great it can melt sand into glass.  And anything that can do that can play havoc with trees.  And tall buildings.  Igniting a lot of fires along the way.  And killing a lot of people.  Until, that is, we started using lightning rods on our buildings.  Sharp pointed pieces of metal above the highest surfaces of the building.  We attach these rods to conductors running down the sides of the building to ground rods driven below the surface of the earth.  Providing a ‘path of least resistance’ for that charge to discharge through while causing minimal damage to the building.

Ben Franklin gave us Weather Forecasting, Convection Heating and Lightning Rods as well as the United States

Fascinating information, yes?  What’s even more fascinating is that we can trace these developments back to one point in time.  More fascinating still, we can trace them back to one man.  A curious fellow.  With a fascination for scientific experimentation.  Who went by the name of Benjamin Franklin.  Who pioneered weather predicting when a swirling northeaster hit Philadelphia with winds blowing in from the northeast.  Curiously, though, this storm had not yet ravished Boston.  In direct line with those winds.  But the storm moved on to Boston AFTER Philadelphia.  It was Franklin who observed that the northeaster was a counterclockwise spinning storm that moved northeast.  The winds in Philadelphia and Boston were only the top part of that spinning storm.  And weather forecasting was born.

Convection heat goes back to the Philadelphia stove.  What we later called the Franklin stove.  Franklin didn’t discover convection currents.  Or the stove using convection currents.  But he used the available knowledge to make a practical heating stove.  It wasn’t perfect.  But subsequent improvements made it the standard for indoor heating for about a century or two.

Ben Franklin did not discover electricity.  But electricity fascinated him.  And he discovered that lightning was electricity (yes, he actually flew a kite in a storm).  His experimentation gave us the first battery.  The first capacitor.  The standard of using ‘plus’ and ‘minus’ for electrical charges.  The conservation of charge (you can’t create or destroy an electrical charge.  You can only move it around).  The battery.  The capacitor.  Insulators.  Conductors.  Grounding.  All of the fundamentals of electrical circuits we use to this day.  And let us not forget that one other thing.  The effect of points on electrical charges (pointy metallic things help charges jump air gaps).  Which, of course, led to the lightning rod.  This after he set up the U.S. postal service and printed his newspapers and Poor Richard’s Almanac.  But before his political and diplomatic service.  And role as a key Founding Father.  Being the only one to sign the Declaration of Independence, the Treaty of Paris and the U.S. Constitution.  The document that started the Revolutionary War.  The document that ended it.  And the document that created the United States of America.  A busy man that Franklin was.  And a great man.

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