This is what it was (and should be):

No.  9.8 °C/km is not equal to 9.8 m/sec².  That's just a coincidence of numbers.



This is what Atom changed it to:

No.  9.8 �C/km is not equal to 9.8 m/sec�.  That's just a coincidence of numbers.



Entering special characters in Atom almost works:

Alt 248 enters°:
Alt 0178 enters: ²