A little help needed for a question about weather systems?

The average height of the tropopause varies from 18kms over the equator to 8 kms over the poles.So no air parcel can rise above 18 km over the equator and 8km above the poles as temperature inversion(or isothermal layer) occurs above tropopause.In between the equator and the poles ,the tropopause height varies between these two values.Over 60 degree South latitude,the height may roughly be 11-12 kms and the parcel cannot rise above this level whereas it can rise up to 18 km over the equator.