<P> Level ice is sea ice that has not been affected by deformation, and is therefore relatively flat . </P> <P> Leads and polynyas are areas of open water that occur within sea ice expanses even though air temperatures are below freezing, and provide a direct interaction between the ocean and the atmosphere, which is important for the wildlife . Leads are narrow and linear--they vary in width from meter to km scale . During the winter, the water in leads quickly freezes up . They are also used for navigation purposes--even when refrozen, the ice in leads is thinner, allowing icebreakers access to an easier sail path, and submarines to surface more easily . Polynyas are more uniform in size than leads and are also larger--two types are recognized: 1) Sensible - heat polynyas, caused by the upwelling of warmer water and 2) Latent - heat polynyas, resulting from persistent winds from the coastline . </P> <Ul> <Li> <P> Aerial view showing an expanse of drift ice offshore Labrador (Eastern Canada) displaying floes of various sizes loosely packed, with open water in several networks of leads . (Scale not available .) </P> </Li> <Li> <P> Aerial view showing an expanse of drift ice in southeastern Greenland, comprising loosely packed floes of various sizes, with a lead developing in the centre. (Scale not available .) </P> </Li> <Li> <P> Aerial view showing an expanse of drift ice consisting mostly of water . (Scale not available .) </P> </Li> <Li> <P> Close - up view inside a drift ice zone: several small rounded floes are separated from each other by slush or grease ice . (Bird at lower right for scale .) </P> </Li> </Ul> <Li> <P> Aerial view showing an expanse of drift ice offshore Labrador (Eastern Canada) displaying floes of various sizes loosely packed, with open water in several networks of leads . (Scale not available .) </P> </Li>

The following relationship between temperature and arctic sea ice is an example of