Can't Blame Coriolis!

The Chicago Bears lost a heartbreaker at home yesterday to the Philadelphia Eagles, 16-15, in an NFC wild card playoff game.  Cody Parkey missed a 43-yard field goal at the end of the game that would have given the Bears the victory.  The ball he kicked first hit the left upright, then hit the crossbar on the way down, bouncing off in the wrong direction for the Bears.  Check out the the ball hitting the left upright (click on image for a larger view).

The Bears play their home games at Soldier Field, which is at a latitude of 41.8632 degrees north, according to Wikipedia.  A closer look at the stands in the background shows section 151 (click on image for a larger view).

I looked at the seating chart for Soldier Field, and then checked that the field does indeed run south to north.  Section 151 is behind the north end zone, which means Parkey's kick left his foot traveling north toward the left goalpost.

The Coriolis effect arises because the Earth turns on its axis, which means we here on Earth's surface are not in an inertial reference frame.  Earth turns once on its axis in 24 hours, which gives a rotational speed of about 0.73 microradians per second or 15 degrees per hour.  Just after the kick and before the ball hit the upright, the ball was in the air for 2.33 seconds.  At the latitude of Soldier Field, Parkey's kick would have only deflected about a tenth of an inch due to the Coriolis effect.  But what's really important is that a ball kicked to the north in the northern hemisphere will be deflected to the right, i.e. east.  That means that the Coriolis effect actually helped Parkey's kick!  Without the added tenth of an inch to the right, the ball still would have hit the left upright, but just a tiny bit closer to the center of the upright.

I feel bad for Cody Parkey.  His kick would have won the game for the Bears.  The snap was perfect, and the hold was perfect.  Parkey just missed the kick.  He even got a little push in the right direction from the Coriolis effect.