Frontal low pressure system
The cloud patterns visible on this GOES satellite image illustrate
features typical of mid-latitude frontal low pressure systems affecting
eastern Canada, including Newfoundland, throughout the year, particularly
during fall, winter and spring. On this occasion an area of low pressure
covers the Great Lakes region, with associated layers of cloud at various
elevations, the tops of which strongly reflect the sunlight, therefore
appearing as bright, near-white masses on the image. To the east (right
side of the image) are frontal zones associated with this system. The more
northerly warm front, which extends eastward across the waters south of
Newfoundland, marks the boundary zone between cold air further north and
much warmer, moist air slanting upward from the warm Gulf Stream current
and producing thick clouds and precipitation near the front, although skies
are quite clear in the warm sub-tropical air further south toward Bermuda.
West of this warm air sector is the cold front, which is advancing eastward
from the eastern seaboard of the U.S. It marks the leading edge of cool,
drier, continental air, and is recognisable on the visual image as a narrower
NE-SW line of bright, (i.e. deep), cloud, formed as the warm, moist air to
its east is undercut and forced to rise by the denser cool air replacing it
from the west.
©1998, Environment Canada.