Sea ice forms during the fall and winter as temperatures cool, and melts during the spring and summer as temperatures increase. Ice that does not grow thick enough during the winter melts completely during the spring and summer and is called first-year ice. Ice that does not melt completely in the summer, but instead remains until the following winter and continues to thicken is called multi-year ice.
But what about all the ice on land?
The other major type of ice found at the poles is called glacial ice. Glacial ice is formed when snow is compacted. As snow accumulates year after year, new layers bury and compress the previous year’s snow. Over time, the snow compacts into ice crystals and air pockets are pushed out, forming ice.
Here are some other terms you may have heard associated with ice.
Iceberg: A chunk of glacier that has broken off and is floating through the ocean.
Pack ice: The same thing as sea ice. Just another name.
Ice sheet: A really, really big area of glacial ice that covers the land surrounding it. Ice has to be over a certain size to be considered an ice sheet. The only ice sheets that exist are in Antarctica and Greenland.
Continental glacier: Another name for an ice sheet.
Ice cap: Kind of like an ice sheet, but smaller. An ice sheet is 50,000 sq. km or larger, while an ice cap is smaller than 50,000 sq. km.
Ice shelf: A permanent, floating mass of glacial ice that exists on the coast of a landmass.
