Dense Fog Advisories were issued for portions of Acadiana this morning, and that included the Baton Rouge area.

Steve Caparotta of WAFB in Baton Rouge posted a time-lapse video of the fog rolling in on the Mississippi River this morning. Within less than 45 minutes, visibility was dangerously low.

I should have learned this in 8th grade Science, but the term for fog forming in this manner is advection. National Geographic explains it in this way:

Advection fog forms when warm, moist air passes over a cool surface. This process is called advection, a scientific name describing the movement of fluid. - National Geographic

The Mississippi River is still cool from the cold temperatures upstream, so when the warm air of South Louisiana hits it: KABOOM!  Well, maybe not that dramatic, but that's when the fog forms due to advection.

Can you tell what my new word-of-the-day is?

If you must drive in foggy conditions, the National Weather Service recommends following these guidelines:

  • Leave early if you must be at your destination at a set time. Leaving early will allow for slower speeds.
  • Turn on your headlights manually. Don't rely on the automatic lights, as sometimes they just turn on your headlights and not your tail lights. When you turn on your lights manually, it will allow people to see you from the front (headlights) and from the rear (tail lights).
  • Do NOT use your high beams. The water droplets that make up the fog will reflect those high beams right back into your eyes, limiting your visibility. Turn on your headlights, but always use your low beams.
  • Travel with extra space between you and the vehicle in front of you. Keep a keen eye on their tail lights.

Also, according to Louisiana state law, it is illegal to drive with your hazard lights flashing in Louisiana, except in certain emergency situations. Or a funeral.

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