A massive, young, and hot star that is moving quickly through space. Runaways are probably propelled through space from a binary star when its companion has exploded as a supernova, or ejected from a
stellar cluster by the dynamical interactions in the system.
Runoff is a term used to describe the flow of water, from rain, snowmelt, or other sources, over the land surface, and is a major component of the water cycle. Runoff that occurs on surfaces before re
aching a channel is also called a nonpoint source. If a nonpoint source contains man-made contaminants, the runoff is called nonpoint source pollution. A land area which produces runoff draining to a common point is called a watershed. When runoff flows along the ground, it can pick up soil contaminants such as petroleum, pesticides (in particular herbicides and insecticides), or fertilizers that become discharge or nonpoint source pollution.
That part of precipitation that does not evaporate and is not transpired, but flows through the ground or over the ground surface and returns to bodies of water.
(1) Discharge of water divided by the area of the drainage basin contributing water to the measurement cross section, expressed in specific units such as mm w. E. D-1 or kg m-2 s-1. (2) The flux of wa
ter leaving the glacier. Sense 2 is common in mass-balance studies, especially in studies of ice-sheet mass balance. See mass-balance units; it is useful to have one word for total flux and a different word for specific flux, so the distinction between discharge and runoff is to be encouraged. Runoff includes meltwater discharge but also water from other sources than melt, such as rainfall.
The altitude above which all rainfall and surface melt, if any, refreezes in the snow or firn, and below which part or all of it runs off the glacier. See zone.