The vertical component, when it is directed upward, of the glacier-flow velocity vector at the glacier surface, at a point fixed in space. When the component is directed downward, it is called the sub
mergence velocity. The emergence velocity is related through the continuity equation to the climatic-basal mass balance and the rate of thickness change. The component is typically upward in the ablation zone and downward in the accumulation zone.
An area on the Sun where new magnetic flux erupts. An EFR is a bipolar magnetic region that first produces a small bipolar plage visible in the chromosphere, which may develop an arch filament system
and the initial spots of a sunspot group. An EFR may be isolated from other solar activity or may occur within an active region.