You hear this a lot in Chicago. “We are having a cold snap because there is a low-pressure system over the Midwest and a high-pressure system to the North. This causes windy conditions which brings cold air down from Canada.”
This sounds better than just saying “it’s cold today” but I can’t tell if it really is saying anything more than that. First of all, as I have said before the following two statements are equivalent, at least empirically:
- The air is colder than usual
- The air was blown here from some place colder than here.
So telling me that the air came from Canada isn’t telling me much more than I already knew, it’s cold. But the extra bit here seems tautological at an even deeper level because these two statements:
- The air is blowing from down Canada
- There is high pressure in the North and low pressure here
appear to be literally the same thing. Why else would the air move from position A to position B if it were not due to pressure imbalances?
Is meteorology really just like finance? (“Stocks fell today because of bearish investors”) Or is there a non-circular way of explaining my frozen toes that just doesn’t fit into a 30 second weather report?