This phenomenom can happen at any time of year but is usually associated with the hot air found over the island during the summer months.
Ranging in time scale from a few hours right up to a week or so, the Calima is a cleaner's nightmare.
Essentialy what happens is that a duststorm is stirred up by high winds in the Sahara and is then driven over the Canary Islands by south easterly winds.
The fine sand particles cause the air to become thick and visibility becomes rather like that experienced during a thick fog.
After a while the Calima dissipates but not before leaving a generous layer of red dust on every surface it passes over.
