Long, linear areas of open water that range from a few meters to over a kilometer in width, and tens of kilometers long; they develop as ice diverges, or pulls apart.
Any fracture or passage-way through sea ice which is navigable by surface vessels. A more general description of a lead is an area of open water or new ice between ice floes, although the term is gene
rally applied to linear features. If the open area is very large it may be called a polynya. A lead between the shore and the pack ice is called a coastal lead or shore lead, and a lead between the fast ice and the pack ice is called a flaw lead.
A more than 50 m wide rectilinear or wedge-shaped crack from several kilometers to several hundreds of kilometers in length. At below freezing temperatures, new, nilas and young ice forms at the surfa
ce of leads.
In a magnetically bipolar or multipolar sunspot group, the main spot in that portion of the group west of the principal inversion line; also called the preceding or p-spot. Leader and follower describ
e the positions of spots with respect to apparent motion due to solar rotation.