A vortex is a turbulent flow which resembles a tornado. Or, maybe it is better to say that a tornado is a well known example of a large vortex. A vortex is also formed as water goes down a drain, as in a sink or a toilet.
... were convicts) at the beginning of 20th century, the population grew to 673,100 today, 83% from whom are Russians. The largest settlement on the island is ...