It is coming from the northern, cooler portion of the source region. Its surface layers remain cool because it moves over cold ocean currents. Its upper portions warm adiabati-cally because of subsidence. Throughout the year, airways are smooth. The skies are clear to partly cloudy.
Clouds are generally patches of stratocumulus, and rain is rare.
The chief flight hazard in this air is coastal fog, which often hides the California or European coastal land. Stratus and stratocumulus clouds may cause the sky to be overcast, develop low ceilings, and produce drizzle that reduces visibility. South of a subtropical high. This produces scat-tered cumulus. Near the equator, after absorb-ing much moisture and being heated, this air may develop cumulonimbus.