Are EMP effects line-of-sight, or do they act like a current?

I understand very little about the physics of things like this.

If an EMP caused by a massive solar flare was aimed toward Earth, would it affect just the side of the Earth that was facing the sun, or would it arc all around the planet?

Would a deliberate man-made EMP, delivered by rocket and detonated high above the Earth be any different in the way it acts than a solar flare EMP, other than size or power?

I'm not sure I'm asking this correctly, so feel free to assume.

Sounds like a valid question and stated so that I understand it... I only wish I had the answer.

...awaiting answer too

EMP effects are pretty short range, they effect a large area onlt if they are generated high enough in the atmosphere (>few 100km) such that the particles produced can spread over a large area as they arrive at the surface.

The local range of the effects of particles arriving at the surface is similair to that of lightning. You can think of an EMP device as the equivalent of starting a large number or lightning strikes over a large area (although EMP does not cause lightning).

Solar flares do not generate EMP, they do produce an electric current in structures near the poles and do inject low energy particles into the atmosphere - again mostly near the poles.

http://eo.nso.edu/MrSunspot/answerbook/polarity.html

An EMP would be much more localized than a massive solar flare. The Carrington Event is quite a scary proposition. Basically, if it conducts a current, then it's vulnerable. On the local scale, I think the EMP would be more catastrophic, but on a larger scale, the CE would probably cause more damage as it raced through the power lines.

Okay, so they're not the same thing... always learning something new.

Looking around online, I found this article on nuclear EMPs which also talks about solar flares (http://www.futurescience.com/emp.html)...

He talks about the Starfish Prime test in 1962 in the Pacific: "The Starfish Prime test knocked out some of the electrical and electronic components in Hawaii, more than 800 miles away. The damage was very limited compared to what it would be today because the electrical and electronic components of 1962 were much more resistant to the effects of EMP than the sensitive microelectronics of today. The magnitude of the effect of an EMP attack on the United States will remain unknown until one actually happens... the magnitude of the all of the components of an EMP are roughly proportional to the strength of the earth's magnetic field. The earth's magnetic field over the center of the continental United States is about twice the strength as at the location of the Starfish Prime test."

The part on solar flares: "Solar flares can also cause current overloads on the power grid that are very similar to the slower E3 component of a nuclear electromagnetic pulse. There is good reason to believe that the past century of strong human reliance on the electrical systems has also, fortunately for us, been an unusually quiet period for solar activity. We may not always be so lucky.

[refers to the 1859 Carrington Event] "... if such a geomagnetic storm were to occur today, it would shut down the entire electrical grid of the United States. It is likely that such a geomagnetic storm would destroy most of the largest transformers in the electrical grid. Spares for these large transformers are not kept on hand, and they are no longer produced in the United States."

While the author is most interested in indicating how these to problems would affect the U.S., is he also seems to be saying that the effects would be somewhat limited, as in all of N. America, all of Europe, etc?

But then he goes on with "A solar storm of the size of the 1859 event, or even a smaller geomagnetic storm that occurred on May 14-15 in 1921, could simultaneously knock out the power grids of the United States, Canada, northern Europe and Australia, with recovery times of 4 to 10 years (since the solar storm would burn up large transformers worldwide, for which very few spares exist.) The United States has no capacity for building replacements for these large transformers."

If I am understanding all of this correctly, would he be indicating that only the half of the world facing Sol would be affected by a solar flare?

It is best to think of an Electro Magnetic Pulse as a very short burst from a very strong radio broadcast. What happens is just like the radio waves from a broadcaster causing a small electric current in your radio antenna. Your radio or TV picks up those voltages and currents from the antenna then amplifies them to make the sound you hear.
The EMP creates a very strong set of current because the EMP device is much much more powerful than a radio broadcaster's station.
The voltage and currents it makes are strong enough to fry diodes, capacitors and especially transistors. Modern electronics are all chip based. Electronic chips are super miniaturized arrangements of capacitors, diodes, and transistors with some really fine transistors in the mix. Because they are so small they are much more likely to be fried by the high voltages and current than old systems with heavier components.
(We usually do not think about the chip having the same things in it as a normal circuit but cause they are all microscopic in size and sold as an integrated circuit chip.)

The EMP is normally short wave lengths too. The chips do not need to be connected to a proper antenna to fry. Almost any wire connected to them will do, even the line printed on a circuit board can act as an antenna. That is why they recommend placing radios etc inside a metal box. The hope is for the box to act as a Faraday cage and shunt the magnetic wave around the electronics.

EMP as a weapon is one of the great untried experimental weapon systems.
If anybody has tried using one they have never published the results.
Experiments with EMP which have been published are not totally convincing about how effective it would be.

Not all chips fry, not all radio tubes are immune.

Yes, a CME could last 24-48 hours and so would give most of the Earth time to enjoy it.

I'm sceptical about the claim that all the transformers would melt, powergrids have a lot of safety systems to protect them from natural events and idiots. The huge blackouts seen in the US and Canada are precisely because of this - at the first sign of anything bad happening systems disconnect everything - leaving people without power, but preserving the infrastructure.

It takes a deliberate level of stupidity to force the system to damage itself - Enron and unregulated markets for power transfer are more effective than an EMP.

I sincerely hope you are right.

From what I've read, I suspect grid transformers to be some of the most vulnerable. They are directly connected to some of the best long-wire antennas out there (high voltage transmission lines) and with the quick rise-time of an EM Pulse, their protective circuitry won't have time to do its job. Just about anything else can be locked away in a SEA-LAND container, but the grid itself is just out there.

Susan, you may want to google "Perfect Disaster" "solar storm". Perfect Disaster is a series on the Discovery Channel. Very good layman's explanation. There is a great explanation of the burning out of transformers.