Just found another I2C sensor for the atmosphere - a lightning detector!
The ASM As3935 breakout board. Looks to be easy to interface. Ordered one to test.
Looks like it detects the electrical energy signature at a specific frequency of lightning containing storms.
Would be interesting to fly on a rocket or a HAB ... it does detect distance to the storm - between 5 and 40 km. I wonder how that information would correlate with other information we can collect on humidity, pressure, dust? UV? Temperature?