Bruma seca over Cape Verde

Bruma seca is Portuguese for dry mist and is caused by sand in the atmosphere. This dry mist is something that affects Cape Verde from time time.  The sand is blown from the Sahara desert in the north east prevailing wind. If it does occur, it is normally only between December and February. This is not surprising as the prevailing wind is stronger in the winter months. It affects the eastern and southern islands the most (such as Boa Vista, Maio and Santiago), but can on occasion affect some of the other islands.

The problem with the Bruma seca is that it can reduce visibility, but more importantly it can cause disruption to air travel. It is a temporary condition lasting a few days.