You are in a Chilean bay on a clear summer afternoon. The wind was calm at 09:00 but has built steadily from seaward since midday and is now raising a short chop. Which basic meteorological phenomenon is this, and what should you expect this evening?

1. It is the virazón (sea breeze), driven by the land heating faster than the sea; it typically peaks in mid-afternoon and eases after sunset, often reversing overnight into the offshore terral (land breeze)
2. It is a tropical cyclone forming inside the bay; it will intensify continuously through the night
3. It is the terral (land breeze), which always blows onshore and strengthens through the night
4. It is a tidal effect; wind in a bay is produced by the flood tide and stops at high water