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.
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