An ensemble of snow particles raised by the wind to moderate or great heights above the ground. The horizontal visibility at eye level is generally very poor (cf. Drifting snow).
An small irregular galaxy undergoing violent star formation activity. These objects appear blue by reason of containing clusters of hot, massive stars which ionize the surrounding interstellar gas. Th
ey are chemically unevolved since their metallicity is only 1/3 to 1/30 of the solar value.
Pure ice in the form of large single crystals. It is blue owing to the scattering of light by the ice molecules; the purer the ice, the deeper the blue.
Dense glacier ice with a blue appearance accounted for by lack of air bubbles. The crystal structure absorbs all colours except the blue part of the visible spectrum. Strictly, blue ice is ice that ha
s originated by recrystallization upglacier and, having followed a trajectory through the interior of the glacier, becomes exposed at the surface downglacier, a locally zero or negative surface mass balance being implied. The term is used loosely, however, to refer to all exposed ice on the Antarctic Ice Sheet; again, the absence of snow and firn implies a locally negative surface mass balance.
Areas where surface ablation has exposed blue ice. These are sites, usually on large ice sheets, where ice flow has concentrated meteorites that have fallen throughout the catchment area of the partic
ular blue-ice area.
An evolutionary behavior of certain stars, particularly massive stars, which return to the blue stage after becoming a red supergiant. The phenomenon appears as a blueward loop on the theoretical evol
utionary tracks.
The apparent shift of the wavelength towards the shorter wavelength region of the radiation spectrum of an approaching object due to the Doppler effect.