Greeting a stranger and chatting about the weather serves the:

1. The phatic function is language for the sake of interaction. 2. It is seen in greetings and casual talk about the weather. 3. It helps to open, maintain and close the channel of communication. 4. So such chat is phatic, not informative or directive. **Why not the others:** Referential describes things, conative directs the listener, and metalingual talks about language itself. _Source: Wikipedia, "Jakobson's functions of language", section "The six functions of language" (revision 1326316540)_