1993 Cadillac DeVille Owner's Manual - Page 212

DRZWNG IN FOG, MISTAND HAZE ... d Fog can occur with high humidity or heavy frost. It can be so mild that you can see throughit for several hundred feet (meters).Or it might be so thick that you can see only a few feet (meters) ahead.It may come suddenly to anotherwise clear road.And it can be a major hazard. When you drive into a fog patch, your visibility willbe reduced quickly. The biggest dangers are striking the vehicle ahead orbeing struck by the one behind. Try to "read" thefog density down the road. If the vehicle ahead starts to become less clear or, at night, if the taillights are harder to see, the fog is probably thickening. Slow downto give traffic behind you a chance to slow down. Everybody then has a betterchance to avoid hitting the vehicle ahead. A patch of dense fog may extend only for a few feet (meters)or for miles (kilometers); you can't reallytell while you'rein it. You can only treat the situation with extreme care. One common fog condition -- sometimes called mist or ground fog -- can happen in weather that seems perfect, especially at night or in the early morning in valley and low, marshy areas. You can be suddenly enveloped in thick, wet haze that may even coat your windshield. You can often spot these fog patches or mist layers with your headlights. But sometimes they can be waiting for you as you come over a hill or dip into a shallow valley.