The process of phase transition from solid directly to vapor in the absence of melting. Thus an ice crystal or icicle sublimes under low relative humidity at temperatures below 0°C. The process is analogous to evaporation of a liquid. Colloquially the terms are used interchangeably for the solid–vapor transition (evaporation). For growth, the term sublimation has been replaced by deposition since the 1970s. There is evidence that deposition nucleation does occur, although there may be an adsorbed layer prior to nucleation. It appears that most nuclei in the atmosphere require near–water saturation before they initiate ice.