Freeze-up of Sea Ice

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Abstract

Typical advance of sea ice over from late summer to late winter is shown on this map. Sea ice is any form of ice that is found at sea and has originated from the freezing of seawater. Formation of sea ice begins in mid-September in the Canadian Arctic and advances southward through the onset of winter. Sea ice begins to form in the St. Lawrence estuary around the first of January, and advances from coastal inlets into the Gulf of St. Lawrence. Sea ice in Canada normally reaches a maximum extent at the beginning of March.

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Freeze-up of Sea Ice shows the typical advance of the sea ice cover from late summer (mid-September) to late winter (mid-March). The dates shown in the legend of the map indicate the extent of the sea ice cover at those dates.

Map Description

Ice will form first in shallow water, near the coast, over shoals, banks; particularly in bays, inlets and straits in which there are no currents. Also in areas of low salinity (near the mouths of rivers). Shallow water is conducive to ice formation because of the relatively small depth of water that has to be cooled. The greater the depth of high-salinity water, later the time of freezing. In fact, deep waters may never freeze over entirely, as not enough heat can be removed from the water during the course of a winter to bring this about.

Formation of sea ice begins in mid-September in the Canadian Arctic and advances southward through to the onset of winter. Sea ice begins to form in the St. Lawrence estuary around January 1st and advances from coastal inlets into the Gulf of St. Lawrence. Sea ice in Canada normally reaches a maximum extent at the beginning of March. At that time, sea ice is usually present in coastal waters of Canada except for those of British Columbia where warm ocean currents from the south prevent the formation of sea ice.

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Navigating in ice and smoke in the Gulf of St.Lawrence during winter time.

Sea Ice Animations

Two animations are created for sea ice. Each animation was presented in two different formats: flash and html. The Atlas of Canada relies on Macromedia’s technology for the delivery of multimedia content. The Atlas of Canada media player will attempt to detect whether you have the necessary software installed, and will give you notice if you do not. In order to play the animations in flash, you must install the Macromedia Flash Player. Installation instructions on Macromedia Flash Player are available at Macromedia Web site.

• Animation of the Minimum Extent of Sea Ice 1969 to 1998 presents the variation of the minimum extent of ice between each year for the period 1969 to 1998, with a concentration of 9/10 or greater. A concentration of 9/10 corresponds to at least 90% of the water which is covered by ice. flash or html
• Animation of the Seasonal Change of Sea Ice presents a normal ice season in Canadian waters by showing the normal evolution of sea ice throughout the course of a year. The animation does not reflect any real observed sea ice season, but rather a 30-year statistical compilation. flash or html