Why does my smoke exit the liner like this?

[ikessky]

I was outside the other day and noticed that when smoke is exiting my liner and cap, it doesn't just go out at an even level. It exits, rolls around the crown of the chimney making it dirty and then goes away. Could it just be where my house is situated as far as the elevation around me?

 

[Chettt]

My guess is the wind is being shaped and channeled by your roof.

 

[polaris]

Yup, very common. An all metal chimney will typically get stained just below the cap on the side away from the prevailing wind(mine does).
Joe