Temperature variation in the WSM

Hi, Harry. Thanks again for all your advice and effort to help folks here on the board. You're a good guy.

Have you ever used multiple pit temperature probes to test the temperature variation from the bottom rack (closest to your foiled water pan) to the top rack, or even the extra top rack (if you are using an extender)?

I've begun to figure out that my WSM racks have significant temperature variations, with the lower ones hotter and the top ones cooler. Have you investigated this at all?

Rule of thumb is bottom grate is about 10 degrees hotter. My temp probe is always on top grate.