Me on this question? log x-log 9=1

This is because:

   log(x) - log(9) = 1

Subtracting the logs of numbers gives you the log of
the quotient of the numbers.

     Log(x) - log(9)  is the log of  (x/9).

So the equation says:    log (x/9) = 1

Raise 10 to the power of each side:  10^(log of x/9) = 10^1

But  10^(log of x/9) is x/9, and 10^1 is 10.

So        x/9 = 10

             x  =  90

When the warmer parts go up and the colder parts go down in a circular motion.