Usually, it is measured in terms of K-value. Storms are often K=4, K=5, or K>=6 (Major or Severe storm). 'The K index measures the deviation of the most disturbed horizontal component of the magnetic field.'
Here is a nice description of what K-value means -- in practical terms, you need a certain K-value to have a chance to see the Aurora at...
You have to admire the Aristotelian tightness of the logic: There is no such thing as a vegetable. Pizza, clearly, exists. Therefore, Pizza is not a Vegetable.
A highly placed Democratic source weighs in on the current state of Super Committee negotiations. “Conversations are still happening, but its mostly about how to put this thing to bed,” the aide says. In other words, the ongoing conversations are mainly about putting the best face on failure rather than finding actual agreement.
